Earth sciences field work along jointiapur tamabil-jaflong section; sylhet

Md. Syadur Rahaman
EARTH SCIENCEs FIELD WORK ALONG
JOINTIAPUR-TAMABIL-JAFLONG SECTION;
SYLHET
REPORT SUBMITTED BY
NAME: MD. SYADUR RAHAMAN
EXAM ROLL: 314
Registration No: 2012-912-210
SESSION: 2012 – 2013
Report Submitted In partial Fulfillment of the
Requirement for the Syllabus of 1st Year B.S
(Hons.) in Department of Disaster Science and
Management
DEPT. OF DISASTER SCIENCE AND MANAGEMENT
FACULTY OF EARTH AND ENVIRONMENTAL SCIENCES
UNIVERSITY OF DHAKA
MAY 2014

3
ABSTRACT
The report may be considered as a complete sketch that is based on the field work carried out in
Jaintiapur& adjacent areas of Sylhet district that lies between 25˚04̕N to 25˚11̕ latitude & 92˚E to
92˚12̕E longitude. The area is characterized by an east-west trending faulted anticline a regional
unconformity is marked by the laterite bed placed between Barail and surma group. Another
regional unconformity is observed between recent gravel deposit and Tertiary rock sequences.
There is a ideal place to Identifying geophysical and hydrological hazards.
Monotonous successions of Tertiary sediments, comprising mainly of sandstone, siltstone, shale and
clay stone are exposed in different section of the investigated area. By correlating, the area is
divided into nine lithostratigraphic units from bottom upwards Sylhet Limestone, Kopili Shale,
Barail Group, Surma Group, Tipam Sandstone, Girujan Clay and Dupi Tila Formation, Dihing
(Sonatila gravel bed). The age of this formation ranges from Eocene to Recent. So, this is the only
area in Bangladesh where the whole tertiary sedimentary sequences (except Tura Formation) are
well exposed. The study of stratigraphic characteristics of this area is very important. This area
comprises the complete Tertiary succession of Bangladesh except Tura sandstone. And the Recent
Alluvium. The deposition of the sediments involves shallow marine to continental environment
with a fluctuating energy condition.
This area lies under threat of Geological, Hydrological and Meteorological hazards. It’s the lower
land beside Shilong platu. So every year it faces flash flood. Here lies many fault zones so this
region is Earthquake prone area. Their soil is acidic. So they can’t cultivate their land properly. The
place is having large amount of environmental degradation. The land users are cut hill and forest
that may a large negative impact on environment.

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ACKNOWLEDGEMENT
Strong team effort is always required to perform a successful field work. This report is an output of
combined effort of many people. So, it is my responsibility to thank all the related people.
I can’t express my honour to our Chairman sir Professor Dr. A S M Maksud Kamal, for his valuable
time spend for arrangement this field work. I express my thanks and deepest sense of gratitude to our
team leader Md. Shakhawat Hossain and Dewan Mohammad Enamul Haque, Both are Lecturer,
Department of Disaster Science and Management, University of Dhaka for Their spontaneous
arrangement and caring guidance. They deserve our thanks for his valuable lectures, good planning
for the trip and great affection. His theoretical and Practical knowledge help me much to clarify my
concept and complete this report.
I also express my thanks of our respected teachers Md. Marufur Rahman, and Tasnuva Tavassum;
Lecturer, Dept. of Disaster Science and Management Department for their environmental and
Statistical suggestion and cordiality and his friendly attitude during field work.
Special thanks to Jaintapur Upazilla Council for accommodation support and in other purposes. I am
quite convinced with the committee of food, transport and other first aid for their great and quick
voluntary service and all to my classmates and to my group leader for their sincere co-operation.
My thanks also extend to the personnel of Department of Disaster Science and Management, and
Dean Office, Faculty of Earth and Environmental Science for the cooks and the laboratory and office
assistants. I specially thanks to that they help us by arrangement and give financial help for our field
work.

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CONTENTS
Page No
Abstract I
Acknowledgements II
Contents III
Chapter 1: Introduction 01
1.1 Location, Extent and Access 02
1.2 Objective, Purpose and Scope 03
1.3 Methodology 04
1.3.1 Field Investigation Method 04
1.3.2 Hazards Identification Method 05
1.4 Climate and Weather 07
1.5 Drainage and Water supply 08
1.6 Demography 11
1.7 Soil and Agricultural condition of the Study area 13
15
2.1 Tectonic Evolution of Bengal Basin 16
2.2 Tectonic Set up of Sylhet Trough and Surroundings 19
2.3 General Stratigraphy of Sylhet 20
2.4 Lithological Descriptions of Investigating Area 23
2.3.1 Sylhet Limestone 23
2.3.2 Kopili Shale 26
2.3.3 Barail Group. 27
2.3.4 Surma Group 29
2.3.5 Tipam Sandstone 32
Chapter 2: Geology of Study area

6
2.3.6 Grujian Clay 35
2.3.7 DupiTila Formation 36
2.3.8 Dihing Formation 37
Chapter3: Hazard and Environmental Problems of Study area 39
3.1 Introduction 40
3.2 Hazards of Study area 42
3.3 Causes of Natural hazard and Environmental problem 47
Chapter 4: Conclusion 49
Chapter 5: References 52
Chapter 6: Appendix 54

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1.1: LOCATION, EXTENT AND ACCESS
The investigated area is located in the north-eastern part of Bangladesh. This area lies on the southern
foothills of Khassia-Jaintiapur Ranges of Meghalaya and is mapped between latitude 250
0/
N and
250
12/
30//
N and longitude 920
0/
E and 920
27/
30//
E and covers the survey of Bangladesh topography sheets
83c/4 of scale 1: 50,000 (Map 1.1).
The studied area belonging to the Jaintiapur Thana in Sylhet district that about 45 km NNE direction of
Sylhet towns and is also about 189 km NNE of Dhaka. The investigated area comprises Afafifanagar tea state
area, Nayagang area, Jaintiapur–Tamabil road section, Shari river section, Dupigoan area, Dauki river
section and Sonatilachara. The total studied area covers about 140 sq km with rough length of about 16 km
in the NNW-SSE direction. Our base camp was about 720m away from the Jaintiapur highway. (Map 1.2)
The Sylhet town is well communicated from Dhaka by three ways- train, bus and air. Jaintiapur Thana is
connected with the Sylhet town by the metalloid road. The same road is followed for going to Jaflong, Sripur
and Sonatila area. Nayagang section is well communicated very near from the base camp and easily
accessible by footpath. The Lalakhal Tea Estate is linked with Jaintiapur by non-metalled road. It is also
accessible by boat upstream along the river Shari, locally known as ‘Shari’, from the Shari ghat. This area is
accessible throughout the year.
Map 1.1: Location Map of Jaintiapur, Sylhet

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1.2 OBJECTIVE, PURPOSE AND SCOPE
The study of Geology is very much dependent on field investigations because theoretical knowledge is not
sufficient to fulfill its demand. The field work performed in Jaintia and its adjoining areas is included to our
study to enrich our practical knowledge. Field work is an important way that gains practical knowledge
about geology. Knowing about geophysical hazard of a area field work is important one.
The main purpose of the field work is gain knowledge about geological settings and identification of hazards
of that area. Also familiar with methods of geological mapping as well as systematic sampling covering
aspect of geological hazard profiling and management of geological and hydrological disaster.
The studied area includes Jaflong, Sripur, Jaintiapur and its adjoining area and also Shari River in Sylhet
district. This area is a paramount place for geological study because in Bangladesh it is the only place where
the whole Tertiary sequences except Tura Formation, are well exposed. It’s an ideal place that knowing
about geophysical hazards.
This report shows the preliminary information of that area. It may be helpful in further investigation of the
area in future.
1.3 METHODOLOGY
Any work is done by some method. In a field work there take several methods. Here flow flowing two
methods for investigation.

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1.3.1 Field investigation method:
The investigation was carried out in the field by adopting very usual “traverse method” that is
walking on foot through road-cut and stream-cut sections. Field investigation involves the
following procedures:
Taking location and bearing, Structural investigation, Lithologic changes and Stratigraphical
investigation, Collecting samples, Construction of geologic maps Taking photographs.
Taking Location and Bearing
Location of the suitable sections and different spot heights of the area were determined by help of
the base map and our instant positions were plotted on the map by the clinometer and a
remarkable point on the map. Bearing of the sections were measured by the help of a clinometer.
The Lithologic Investigation
Good exposures were studied for the lithological information of the rocks which were subdivided
through observing different color, composition and distinguishable contacts of different rock strata.
General grain size, sorting and mineralogy of the rocks (those are determinable in the field) were
determined approximately by the necked eyes or by the help of the hand lens. Reactions with HCL
ensure the presence of carbonate (CO32
) in rock.
Structural Investigation

11
Attitudes of the beds were measured by the clinometer and for the rough, disturbed andvegetated
beds; hammer was used for breaking the rock and getting fresh bedding planes.
Stratigraphical Investigation
The thickness of the exposed rock strata were measured by taking pacing and from the map. The
stratigraphic succession of the beds was made by observing their positions to apply the "Low of
Super Position" and by the study of their lithology and thickness. Unconformity was determined by
observing the presence of erosional surface, soil and distorted bed of lateritic conglomerates
between two different rock units.
Collecting Samples
Samples of different rock strata of different sections were taken in sample bags for further study.
Tacking Photographs
The important photographs of physical features, sedimentary structures, important rock units and
structural features (fault, fold, joint, unconformity, hazardous place etc.) of the area were taken by
the camera.
Construction of Geological Map
The measured attitudes and lithology of different beds were plotted on the base map with proper
reference points to prepare a geological map of the area.

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1.3.2 Hazard Identification Method
A Hazard Identification Study is the process of identifying hazards in order to plan for, avoid, or mitigate
their impacts. Hazard identification is an important step in risk assessment and risk management. The tool
can be used to determine the adverse health effects of exposure to a chemical stressor and to plan for
building repair costs or retroffitingin areas prone to natural disaster.
The methodology for each of the hazard identification techniques is briefly described, preceded by which
hazards are identified.
We use two types of technics
1. Focus Group Discussion (FGD)
2. Attend a seminar
A focus group is a form of qualitative research in which a group of people are asked about their perceptions,
opinions, beliefs, and attitudes towards a product, service, concept, advertisement, idea, or packaging.
Questions are asked in an interactive group setting where participants are free to talk with other group
members. Focus group discussion is an important method of investigation a hazard. Local people are a clear
knowledge about hazards that occurs there. We identifieng some hazards by FGD. That we knoing about
flood, flash flood, Slamping. It was also help identifying the environmental problems. We talked a local
people (Fig 1.1) about hazards.

13
Fig1.1: Discussion with local people knowing about Hazards.
Seminar is an easy way to identifying hazards. We attend a seminar to knowing about environmental
degradation and hazards. We attend a seminar on Citrus Research Center there talked about their
environmental, agricultural condition and there problems. (Fig1.2)
Fig1.2: Seminar on Citrus Research Center

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1.4 Climate and Weather
Bangladesh lies under the hot and humid Climatic condition. Here have six seasons, but we find mainly four
season.Sylhet is situated northeastern part of Bangladesh. Our study place is border of Bangladesh. This area
is mainly hilly region, with some flat area. Silongplatue stand north of our study area. So this climate is
control by this Platue.
Because of geological location, the investigated area generally falls under the tropical to subtropical climate.
But as the influence of the humid north-eastern monsoon wind over the general climate of the area is
noticeable, the overall climate of the area is termed as ‘Humid Tropical to Subtropical Monsoonal climate'.
However the area is very much susceptible to heavy monsoonal rainfall causing the periodic flood in the
plains.
So, the climate of the area can be divided in to three distinct seasons in a year. The summer starts from
March and continues up to May having high temperature and moderate precipitation. The monsoon begins
in June and lasts till October and is characterized by gusty wind and occasionally Because of geographical
location, the investigated area generally falls under the tropical to subtropical climate. But as the influence
of the humid north-eastern monsoon wind over the general climate of the area is noticeable, the overall
climate of the area is termed as ' Humid Tropical to subtropical cyclonic storm. The winter begins from
November and exists up to February with a pleasant, Calm, cool and dry weather. (Map 1.3)
The average range of annual temperature, humidity and rainfall of the area ranges from 900
f - 65f, 36% -
99% and 300 cm - 380 cm respectively.

15
Map 1.3: Climate map of Bangladesh
1.5 Drainage and water supply:
In a broader sense the investigated area is lack of any remarkable stream of Bangladesh, but the area is well
drained by a network of locally important streams most of which are both structurally lithologically
controlled and dendritic in pattern (Map 1.4). The relatively major streams are fewer in number and are of
perennial type, that is they flow even in the dry season, but during rainy season they flow with their full
strength and become able to carry large boulders to distant places whereas the minor streams are large in
number and of intermitted type, that is they are seasonal in their flow, and water ceases to flow during the
dry spell.

16
Map 1.4: Drainage patern of Investigated area
However in particular, the general water distribution of the area is maintained by the rivers namely the
Dauki, the Hari, the Rangpani and the Nayagang.
The river Shari (Fig 1.3) which acts as the main source of water distribution of the eastern portion of the
area originates in khasiaJainta Hills near Jawi in India and maintaining more or less meandering course
flows south westerly to some extent and then bends abruptly towards west and ultimately falls in the Surma
River near Kalaruka.

17
Fig 1.3: Sari River
Among the mentioned four rivers, the Dauki(Fig 1.4) is the most prominent. The Dauki which is a fault
controlled river originated in the southern part of the Shillong plateau, flows by the western side of the
hillocks and enters into Bangladesh at the foot of the Indian Dauki Town in the N-S direction. Inside
Bangladesh it is replenished by a number of seasonal small streams which are locally termed as 'Chara'.
'Piyan' is the main tributary of the river Dauki.
Fig 1.4:Dauki River

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The two main tributaries of the Shari River, namely the Nayagang(Fig 1.5) and Rangapani(Fig 1.6) are the
other two important rivers of the investigated area which maintains the drainage system of the central
portion of the area. Among these two, the Rangapani flows into Bangladesh near Sripur and flows southeast
ward for some distances and turn towards southwest for flowing down to the marshes. The Nayagang enters
Bangladesh near Puranassampara, flows southwest and finally meet the marshes. It is to note that the
Nayagang is a meandering river and the Rangapani is a braided river.
A little or no rainfall in the dry season, cause the lowering of water table and results the severe suffering of
the local people from inadequate supply of drinking water. But in the rainy season due to heavy rainfall, the
aquifer gets filled and water supply becomes well enough. The deep tube wells and dug wells are the only
source of drinking water.
Besides these, many low lying water bodies like swamps, ponds, marshes and bill are also there which dry
up in the winter and water retain during the rainy seasons play an important role in the water distribution
mainly in the plain land of the area, such as Tamabil, Burabil, Bogabil etc
Fig 1.5: Rangapani River

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Fig 1.6: Noyagoan River
1.6 Demography:
JaintiapurUpazila (sylhet district) area 258.69 sq km is bounded by Meghalaya (India) on the
north,Kanaighat and Golabgonjupazilas on the south, Kanaighatupazila on the east Gowainghat and
SylhetSaderupazilas on the west. The hill series of northeast are known as Jaflong Hills. Main river is Sari
Goyan. Haors 2 (KentiHaor and BiraimaraHaor); Kakai, Pitha, Dhupani, Palli and Sat beels are noted.
Jaintiapur (Town) consists of one mouza. It has an area of 2.27 sq km; population 5,769; male 52.71%,
female 47.29%; density of population is 2541 per sq km. Literacy rate among the town people is
47.6%.Jaintiapurthana, now an upazila, was established in 1903. The upazila consists of 3 union parishads,
160 mouzas and 173 villages.
Total population of Jaintiapurupazila is 98270; male 51.02%, female 48.98%; Muslim 89.81%, Hindu
9.59%, Christian 0.17%, and tribal 0.43%; ethnic nationals: 80 Khasi families living in Nizpat and Jaflong
villages. There are 227 Mosque, 7 Temple, 2 Church and 4 Tomb. Average literacy of JaintiapurUpazila is
35.45%; male40.3%, female 30.6%. Educational institutions: college 2, secondary school 4, junior high
school 3, primary school (government) 41, primary school (private) 15, madrasa 16. Central JaintiaHigh
School (1955), Haripur High School (1957) is important educational institutions.Thetre are 17Rural club, 3
playground

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Jaintiapur is a turist spot most of themMegalith Monument, remnants of Jaintiaswari Temple, remnants of
JaintiaRajbari, Sarighat Temple.Occupation of these peopleis Agriculture 38.69%, agricultural labourer
17.77%, wage labourer 12.52%, fishing 2.5%, commerce 7.70%, service 5.69%, and others 14.99%. The
crops are Paddy, tea, potato, garlic, cassia-leaf, betel nut, betel leaf. And fruits are Jackfruit, pineapple,
lemon.Communication system isn’t developed,pucca 60 km, mud road 362 km; waterways play vital role in
rainy season for connecting the low lying areas.Mineral resource of there is natural gas, crude oil.Hats and
bazars 7, mela 3; Jaintiapur, Darbasu, Haripur, Chiknagul, Shukrabari, etc are notable hats and
bazars.Health facilities of there are Upazila health centre 1, family planning centre 5, and satellite clinic 2.
[JayantaSingha Roy]
Culture of entire Sylhet is totally different from others parts of Bangladesh. It is mainly focused on their
language. Their language is called by other people of Bangladesh as” syloti Vasa”. Sylheti attachment to their
regional identity also continues in the efforts of many Sylhetis to keep marital relationships within the same
regional, cultural, social and religious background. Sylheti people are considered as a distinct ethnic
group in Bangladesh; They are also generally more family oriented, follow and support
Sylheti community culture, and are more conformist Muslims. These tendencies have led to some rivalry
between non-Sylhetis and Sylhetis, due to differences of customs.
Marriages are practiced in a traditional Muslim style, with henna ritual (mehendi), and prayers. Sylheti
marriages often include contracts of marriage outlining both the rights and obligations of both partners.
Marriages in Sylhet often take place with partners in the United Kingdom and the US.
Given its unique cultural and economic development, and linguistic differences (Greater Sylhet region was a
part of Assam and Surma Valley State for about 100 years during the British Raj in comparison to the rest
of Bangladesh), and given that Sylhet has, for much of its recent history, been a region of a larger entity. As
so many Sylhetis are resident abroad, Sylhet has a major flow of foreign currency from non-resident
Bangladeshis.
1.6: Soil and Agricultural Condition of the Study Area
Soil of this area is mainly sandy.Soils of the area are grey silty clay loams and clay loam on higher parts that
dry out seasonally and grey clays in the wet basins. The soils have a moderate content of organic matter and
soil reaction is mainly acidic. Fertility level is medium to high. (S.M. ImamulHuq, Jalal Uddin Md. Shoaib ;
The Soils of Bangladesh).The pH of the soil of Jaitiapur is low which means the soil is acidic. It hinders the
crop production. The contents of nitrogen and boron are low. Probably, denitrification process leads to the
loss of nitrogen in the basin soil.

21
Thick vegetation characterizes this hilly area. Different types of trees are found in the area. Bamboos are
very common. The teak plantation is located near Shari River (Fig 1.7). Most of the hilly area is highly
vegetated. In some places the ground is covered by Nolkhagra grasses.
Figure1.7: Vegetation near Shari River
Rice is the principal crop of the area. The floodplain lands are used for cultivation of paddy. The low lying
areas are used for Boro cultivation. Tea is also very important cash crop of the area and a series of tea
gardens are situated in hillocks and valleys from Jaflong to Afifanagar. Fruits such as pineapple, water
melons, oranges, banana, papaw, jackfruit etc and various types of seasonal vegetables are also cultivated.
Several fields near river bank are under water melon cultivation as observed during our investigation
Hilly region soil is acedic. So there find acedic rich fruits, such as citrus fruits. A branch of BARI that name is
Cytrus Research institute. This research center received acidic soil. This research center many types of citrus
fruits such as Bari Kamala-1(Fig 1.8).

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Fig 1.8: Citrus Recherche Center plant (BARI Kamala -1)
Fig 1.9: Recherché Plant in Citrus Recherce Center

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Chapter 2
Geology of Study Area

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2.1 Tectonic Evolution of Bengal Basin
The Bengal basin lies on the eastern side of the Indian sub-continent and occupies most of
Bangladesh and west Bengal of India as well as part of the Bay of Bengal (Alam, 1989). The studied
area is located in the northern part of the Surma Basin or Sylhet Trough which is a basinal
depression in the Bengal Geosyncline.
About 110 million years ago during Cretaceous time, the Gondwana Super continent began to
break up and India began drifting towards north. The Bengal basin was initiated during that time
however; the basin did not become the center of deposition of thick clastic sediments until the
northward drifting Indian Plate collided with the Eurasian Plate. The collision between Indian plate
and Asian Plate took place in stages beginning in Eocene (55 million years ago) when an initial
uplift of the Himalayan occurred.(Fig 2.1) By late Eocene (40 million years ago) the last remnant of
the intervening Tethys sea between Indian Plate and Asian plate probably disappeared as a result of
collision. During this time the direction of Indian Plate Convergence changed from north to
northeast with increasing collision with Asia (Scatter & Fisher, 1974)
Fig 2.1: Upliftment of Himalayas due to collision of Indian plate and Eurasian plate

25
Bangladesh was the site of vast delta buildups during Eocene to Pliocene time. Subsequent
Pliocene-Pleistocene alluvial deposits of the Ganges- Brahmaputran Rivers system ccnpletely
covered the earlier deltaic deposits. These Tertiary strata, below the Pleistocene, have become
campressed into long and narrow, north-south oriented folds, produced during the Alpine
Orogeny by the westward push of the East Indies island arc. The anticlines have gentle east- and
steep west-flanks; thrust faluts are numerous. Deformation decreases westward, and in northern
Bangladesh the fold and fault pattern becomes more easterly trending. Correlation of rock units by
lithologic characteristics has proven to be unreliable; palynologic studies have proved more
reliable
The delta building activities continue along the central part of the basin, although the eastern part
of the basin has since been uplifted into a folded mountain belt i.e. Sylhet-Chittagong Hills. This
represents the frontal or outer western part of a more extensive orogen namely the Indoburman
range. The folded mountain range resulted as a direct consequence of the subduction of the Indian
plate beneath the Burmese plate. The geology of Bangladesh is not yet adequately kncown. Nothing
is known about the pre-Cretaceous geological history. The history of the Indo-Burman Orogen
becomes discernible only from the Late Cretaceous (Senonian) onward
By Eocene, because of a major marine transgression, the stable shelf came under a carbonate
regime, whereas the deep basinal area was dominated by deep-water sedimentation. The folding
can be better observed in the 3D simulation of the Bengal Basin (Fig 2.2).
A major switch in sedimentation pattern over the Bengal Basin occurred during the Middle Eocene
to Early Miocene as a result of collision of India with the Burma and Tibetan Blocks. The influx of
clastic sediment into the basin from the Himalayas to the north and the Indo-Burman Ranges to the

26
east rapidly increased at this time; and this was followed by an increase in the rate of subsidence of
the basin. At this stage, deep marine sedimentation dominated in the deep basinal part, while deep
to shallow marine conditions prevailed in the eastern part of the basin. By Middle Miocene, with
continuing collision events between the plates and uplift in the Himalayas and Indo-Burman
Ranges, a huge influx of clastic sediments came into the basin from the northeast and east. (Alam,
Alam, Curray, Chowdhury, & Gani, 2003)
Figure 2.2: 3D simulation of the Bengal Basin
During the Miocene the depositional settings in the basin continued to vary from deep marine in
the middle part of the basin to shallow marine in the marginal parts. Large amounts of sediment
started filling the Bengal Basin from North and Northwest, starting from the Pliocene times.
The present day delta was formed by the continued delta-building processes. From the Cretaceous
times the structure of the Bengal Basin has been changing due to the collision patterns and
movements of the major plates surrounding the region. Three significant changes in the patterns
can be recognized that occurred during the early Eocene, middle Miocene and Plio-Pleistocene.

27
During this time both the geographic settings and source areas of deposition changed. The present
setting of the Bengal Basin was formed during the later Pliocene and Pleistocene. The delta
progradation was strongly affected by the uplifted Himalayas
2.2 Tectonic Set up of Sylhet Trough and Surroundings
The Sylhet Trough is occupied by an anticline namely Sylhet Anticline, a northeast southwest
trending fold structure with a length of 13 km and an width of 3 km. The structure has discrete
four way dip closure. The anticline is arcuate and slightly asymmetric; the asymmetry results in
progressive shift of the crestal axis towards the southeast with increasing depth. The structure is
influenced by several large faults recorded in seismic sections. These are reverse faults. The seismic
section shows evidence of extentional collapse at the crest in shallower horizons and several
normal faults can be traced (Imam, 2005).The investigated area and adjoining area lie within the
Sylhet trough of Bengal foredeep. Sylhet trough is situated south of Shillong Massif (Map 2.1) and
corresponds with vast low land of Surma basin. The northern limit of this subsiding trough is
bounded by well-known Dauki fault. Dauki fault system is probably included in the same system of
thrust faults, Disang and Naga of Assam (Map2.1). Faulting along the Shillong shelf zone coincided
with rapid subsidence of Surma basin is during Miocene and later time.
The structure of the investigated area is one field team estimated Anticline. Khan, 1978, told it is a
broad homoclinal fold, a small anticline and syncline. Refolded structure formed due to the right
lateral movement of Dauki fault. Tectonically, the structure of the Surma Basin and its adjoining
areas are more active which is evidenced by the subsidence of the Surma Basin is about 30 to 40 ft
within the last several hundred years. The Surma Basin is subsiding at present day at a rate of
21mm per year in central part and 1.5 to 2.5 mm per year in northern part. Theforced responsible

28
for the development of the structure of the area are due to the under thrusting of the Indian plate
towards NNE direction (Paul, 1988).
Map 2.1: Sylhet Trough and Surrounding Area
2.3 General Stratigraphy of Sylhet
Stratigraphy is the scientific discipline concerned with the description of the rock successions and
their interpretation in terms of a general time scale.It provides a basis for historical geology, and its
principle and methods have found application in such fields as petrology and archeology
.Stratigraphic studies deal primarily with sedimentary rocks but may also encompass layered
igneous rocks (e.g. those resulting from successive lava flows) or metamorphic rocks formed either
Dauki Fault
Surma Basin
Sylhet Trough

29
from such extrusive igneous material or from sedimentary rocks. A common goal of stratigraphic
studies into mappable units, determining the time relationships that are involved and correlating
units of the sequence or the entire sequence with rock strata elsewhere. A regional topographic
satellite image showed the stratigraphy of Sylhet trough. (Map 2.2)
The area under investigation is underlain in part by Holocene and flood plain deposits and in part
by deformed Tertiary sediments. Most of the outcrops are covered with thick jungle and soil and
accessible with difficulty. Along the Shari River there is an excellent section which can be
considered on the type section for the Neogene sequence in N-E Bangladesh. From the Dauki river
where Eocene limestone crops out to the plain ,south of Dupitila ,2800ft thick sediments has been
estimated (Haque,1982).This monotonous succession of sediments which have been affected by the
movements associated with the Himalayas orogen.Except for Sylhet limestone, the sequence
represents a clastic section composed mainly of sandstone, siltstone, clay and associated
conglomerate. The rock strata were investigated on the basis of lithologic characteristics and were
subdivided on the basis of lithologic contrasts.
Map 2.2: Satellite image which represents Regional topography and stratigraphy of the
investigated area

30
TABLE 2.1: The Stratigraphic succession of NE Bangladesh,Sylhet trough
The stratigraphy of the area has been differentiated into a number of formations. Sylhet limestone
formation is found as the oldest in the normal sequence.The normal sequence of the studied
formation is given below according to the law of superposition.

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1. Dihing formation
2. Dupitila formation
3. Giruja clay
4. Tipam sandstone
5. Surma group
6. Barail sandstone
7. Kopili shale
8. Sylhet limestone
The names of the formations are established by Evans(1932) for the tertiary successions of Assam.
Although it is difficult to correlate formations separated by hundred of kilometer without the
support of paleontological data and also because of frequent facies changes.
2.3 Lithological Descriptions of Investigating Area
The oldest rock exposed in Bangladesh is Tura sandstone of Early Eocene age in Takerghat area in
Sunamganj district in Sylhet division. But this is not found in our investigated area.The Sylhet
limestone formation is the oldest exposed rock in our studied area,the middle unit of the Jaintia
group of sediments.They are overlain by from older to younger the Barail group, Surma Group,
Tipam group, Dupitila and Dihing (Sonatila Gravel) sediments.

32
2.3.1 SYLHET LIMESTONE:
The term Sylhet limestone as a rock unit was first used by F.H.Khan(1963).The formation is exposed
on the left bank of Dauki river near the Bangladesh-Meghalaya border. (Lat N251053.5 Long
E920105.5)The outcrop forms an inlier surrounded by recent deposits and rock of the Barail
group. It is the oldest (Eocene) rock of the investigated area. Limestone is a hard friable rock, thus
are sometime fosiliferous. (Fig2.3)
Fig 2.3: Outcrop of Sylhet Lymestone
The grey coloured, fossiliferous highly compacted limestone offers a variety of fossils from disk
shaped. The hard limestone is highly jointed and fractured .The brecciated limestone occurs due to
large Dauki Fault. The assemblages of dominantly large microfossils indicate shallow water,
continental shelf zone. Fault bractia (Fig 2.4), formation missing, topographic change (Fig 2.5) and
different deep direction are indicating the presens of Dauki Fault.
SylhetLym
eston

33
Fig 2.4: Fault Bractia, Dauki Fault
Fig 2.5: Sudden Topographic change due to Dauki Fault
Sudden
Topographic
change

34
The lithologic description of Sylhet limestone indicates it was formed in a warm, shallow marine
environment of deposition. The Eocene was a period of stable slowly subsiding shelf condition in
the Bangladesh area and was not yet strongly influenced by the continental collision of India and
Asia that began in Late Paleocene. As a result there was no disturbance of any river and that quite
environment was favorable for the inhabitation of marine organisms which we found as fossils in
Sylhet limestone. (Fig 2.6)
Fig 2.6: Contract Between Kopili Shale and Sylhet Lymestone
2.3.2 KOPILI SHALE:
The name of Kopili shale was given by P.Evans(1932) to the beds forming the upper stage of the
Jaintia group after the kopili river of Garo hills in India. It’s friable organic rich shale. It gives a
minor outcrop on the west bank of the Rangapani River (Lat N 251042.3 Long E 920429.5). We
found it on the east bank of the Dauki river (Ballaghat ) near the Bangladesh-Meghalaya
border(lat250
10.891 long 920
, 01.091).
Boundary between
Sylhet Limestone and
Kopili ShaleKopili Shale
Sylhet
Limestone

35
It is dark grey to black colored very much fissile, thickly bedded to paper laminated, poorly
compacted, friable. Interbeded sandstone with argillaceous matrix is present.It is conformably
overlain on the Sylhet limestone. Base of kopili shale is not seen.
In the late Eocene, the environment of the area changed from shallow marine to a clay receiving
basin. At that time the continental collision affected this area. As Himalaya started to rise, finer clay
particles were carried out and the limestone forming environment was disturbed. The water
become cooler and brackish which affected the organism resulting a barrier that terminated the
deposition of limestone? Under such an environmental condition Kopili Shale was deposited.
Fig 2.7: Outcrop ofKopili Shale
2.3.3 BARAIL (Renji) Formation:
The Oligocene is represented by the Barail group, named by Evans(1932) after the Barail range in
nearby Assam,India where the unit has its type locality The Barail group (Renji formation) is well

36
exposed in Mahishmara, Sonatila and near Sripur (Lat. N251037 Long. E920435.7) which is about
3.5 miles NW of Jaintiapur. Most of the exposures are covered by Holocene sediments. The Barail
forms high ridges than the adjacent Surmagroup. Baril is highly compacted sandstone. At
Rangapani River (Lat. N251004.9 Long. E920321.7)
The sandstone is mainly pink in colour, weathered to light yeloow and grey, very fine to medium
grained argillaceous and Ferruginous materials.The siltstone is light grey to yellow in color .It is
thin to thick bedded, fairly hard and compact and well jointed. It is sometime iron incrastation
parallel bedding. Upper of Baril formation we found Laterite conglomerate. It is found cross
bedding lamination in Barial Sandstone.(Fig
Barail Sandstone reflects a delta to near shore environment. During Oligocene Himalayan began to
raise more. So, many new rivers began to flow and carried sand particles and a delta began to
develop. Under this near shore environment a huge amount of sand with some clay particles were
carried out, as a result Barail formation deposited.

37
Fig 2.8: Iron Rich Barail Sandstone
Fig 2.9: Corse Bedding Lamination in Barail Sandstone

38
2.3.4 SURMA GROUP:
The Surma group has been named after the Surma series of Assam,India ( Evans,1932).The
sediments of the Surma group unconformably overlies the Barail group. Good exposures of this
unit were observed in the east of Jaintiapur and in the Hari Riverstop. The surma group is generally
subdivided into two formations namely Bhuban a Bokabil and a contact of Bhuban and Bokabil was
seen at station-4(lat N250
0655 long 920
1055). The Surma group is made of bedded, laminated
siltstone, shale, silty shale, claystone and sandstone. It is also exposed near Jaintiapur i.e.
Afifanagar.Most of it is covered by recent alluvium. The contract between Surma and Tipam
Sandstone is near BGB camp laft bank of sari river.(Fig 2.10)
It is composed of yellowish grey sandstone, bluish grey shale, sandy shale and siltstone .sandstone is
fine to medium grained, subangular and moderately sorted, hard, is resistant to weathering and
forms the cliffs. The shale is bluish grey in color, well laminated, hard and jointed. During Miocene
epoch, the major orogenic enlistment of Himalaya took place. We also found there Flasher and
lenticular bedding siltstone alteration with sandstone.(Fig 2.11) The sand, silt and clay particles
carried and deposited by numerous streams enhanced the development of major delta. Sometime
we found Drag fault in surma group (Fig 2.13). Gradually the delta advanced to the south as the
shoreline retreated. The Bhuban and BokaBil formations deposited under such predominantly
deltaic environment, often showing the evidence of marine transgression for short period. The size
and shape of the grains indicates low energy condition of deposition and long transportation.
Bhuban formation deposited in the early Miocene time and BokaBil is of late Miocene. But same
environmental condition prevailed during the time of deposition of the both formations. This is
evidenced by the similar type of lithology of the formations without any pronounced changes and
their contact was gradational one. Therefore, the environment of the deposition of BokaBil was
Deltaic same as Bhuban.

39
Fig 2.10: Contract between Surma and Tipam Sandstone
Fig 2.11: Lenticular Beding in Surma Group
Siltstone
Sandstone

40
Fig 2.12: FoldingOutcrop of Shale (Surma Group)

41
Fig 2.13: Drag fold in Surma Group in Nayagang
2.3.5 TIPAM SANDSTONE:
The name has been used after the Tipam hills in an Assam, India (Mallet, 1876). The formation
constitute the lower part of Tipam group and is conformably overlain by Girujan Clay. Top of this
formation is exposed in (Lat N250
0637.3 long 920
0906.4).
The top of Tipam sandstone
formation forms a conformable contact with the Girujan clay formation exposed in the bank of
Shari River. Where it consists of alternation of bedded to thick bedded, fine sandstone and
mudstone. (Fig2.17)
Lithology of Tipam sandstone consists of grey-brown to pale grey, medium to coarse grained, and
massive sandstone .Intercalations of grey shale, found conglomerate (Fig2.18), pebbles, laterite bed
(Fig 2.14), Here found clay gol (Fig 2.15), massive sandstone and its conformable existence over the

42
rocks of Surma group offer sufficient clue to assign it as the lower part of Tipam group. So, we may
be permitted to correlate this unit with the Tipam sandstone formation of Assam Basin belonging
an age of Mio-Pliocene.
Upper lithological information says that Tipam sandstone formed in fluvial environment. During
late Miocene to Early Pliocene time, the development of Delta continued and gradually moved
toward south leaving a land environment beyond it. The streams carried out and deposited the
Tipam sediments in high energy condition. Massive bedding and pore to moderate sorting suggest a
nearer source area.
Fig 2.14: Laterite Bed over Tipam Sandstone
Laterite

43
Fig 2.15: Clay Gol in Tipam Sandstone
Fig 2.16: Tipam Sandstone
Cly gol

44
Fig 2.17: Conglomerate on Tipam Sandstone
2.3.6 GIRUJAN CLAY:
The name has been given after the Girujan clay stage of Tipam series in Assam,India. Top of this
formation is exposed in Stop-4(Lat N250
0554.3 long 920
084.4) by the Shari river bank having a
conformable contact with the overlying Dupitila formation. The formation develops conformably
and gradationally from the underlying Tipam sandstone formation. It consists of Grey to bluish
grey, 100% clay and mottled clay. (Fig 2.20)

45
The characteristic properties of the rock unit such as its whitish gray color, massive structure,
sticky nature, and clay content and its conformable relation to the underlying Tipam sandstone
formation permit us to correlate it with the Girujan clay formation of the Tipam group in Assam
basin Assigning an age of Mio-Pliocene.
Right after the deposition of Tipam sandstone, Girujan clay was deposited under the influence of
lacustrine environment in a locally developed lake in the fluvial system. This event is substantiated
by its restricted deposition rather wide spread. The environment required for the deposition of such
clay formation was provided by the standing water body i.e. lake where, finer particles may settle
down.
Fig 2.18: Outcrop of Girujan Clay

46
2.3.7 DUPITILA FORMATION:
The Dupigaon is the type locality of the Dupitila formation which is exposed in station-
1(250
0546.4N and 920
074.3E) at Sharighat behind sharighat primary school. (Fig 2.19) The
lithology is dominantly sandstone and siltstone with interbeds of claystone. The Dupitila sandstone
formation conformably overlies the Girujan clay formation. This is the only formation of which the
type section belongs to the Bengal basin (Bangladesh).
The sandstone is yellowish brown colored, medium to course grained, less compact and highly
porous. It is massive too thick bedded. The sandstone is quartz predominated with significant
amount of mica and dark colored minerals. It contains quartz granule and clay galls and can be
characterized also by iron encrustation. Found cross bedding lamination. (Fig 2.20) Significant
amount of clay matrix is present in the rock and ferruginous cementing material gives the rock this
yellowish brown color. The color of the clay stone is bluish gray. It is very fine grained, massive and
sticky in nature. The composition of the clay stone is entirely clay minerals.
The lithologic characteristics that are presence of clay galls, cross bedding refer a continental
fluviatile environment for the deposition of DupiTila sandstone formation. The DupiTila formation
represents deposition over a broad front of river plane with flood plain and channel deposits.
Sandstone was deposited in the channel proper whereas the claystone/shale was deposited in the
flood plain.

47
Fig 2.19: Outcrop of Dupitila Formation
Fig 2.20: Cross bedding in (Dupitila Formation)

48
2.3.8 DIHING FORMATION:
The Dihing formation of Pleistocene age has unconformable contact with the Surma group and
with Barail group, sonatila Chara. Which are exposed in Stop 1(day 3) lat N 2585.3 long E
92745.3. The formation consists of yellow and grey, medium-grained, occasionally pebbly
sandstone and clayey sandstone with interbeds of mottled clay and boulders. The rocks are in most
part poorly consolidated.(Fig 2.21)
After the deposition of DupiTila, the area had suffered a major tectonic activity. The upliftment of
Shillong plateau caused the tilting of entire Tertiary strata. The area suffered upliftment up to
Pleistocene period, which is evident by the presence of conglomerate beds. A time gap between the
Pliocene DupiTila formation and recent alluvium is represented by these gravel beds.
The Pleistocene river carried those gravels and deposited them horizontally over the inclined
Tertiary succession as bed load deposits.
Fig 2.21: Outcrop of Dihing Formation (Beside our Base Camp)

49
Chapter 3
HAZARDS AND ENVIRONMENTAL PROBLEMS
OF STUDY AREA

50
3.1 Introduction
Bangladesh is a developing country. This country is often known as the country of disasters at the
global level. The socio-economic impacts of natural disasters are very destructive in Bangladesh.
Natural disasters cause the death of many lives almost every year and also create the risks of
poverty, unemployment, disempowerment in the country, which might be a global problem in the
future. Natural disasters often cause food crisis in the country as well. Due to natural disasters,
many people have to depend on aids since they lose almost everything in the natural disasters like
cyclones or flooding. In the context of globalized environmental degradation, Bangladesh is one of
the major victims. Bangladesh has been struggling to cope with this situation for a long time. But
natural disasters as well as effects of climate change often hinder the development of the country as
well as many other states. So, such problem has to be solved globally; rather than locally
Often Bangladesh can be regarded as a super market of both natural and manmade disasters. Our
country is being affected each year by either natural disasters like flood, cyclone, river bank
erosion, landslide, tornado, nor’wester, earthquake, saline water intrusion or manmade disasters
like infrastructure collapse, fire, water logging, ground subsidence due to ground water
withdrawal and transport accidents. Climate change is another problem in globally and tis is severe
in South Asia and as well as in Bangladesh.
Sylhet is our study which is mainly affected by geophysical, hydro-meteorological, environmental
hazards. Anthropogenic hazards are also prominent in this area. Earthquake, slumping, landslide,
flood, flash flood, gravel withdrawing, acidity in soil, deforestation are the main hazards in this
area. All of them flash flood, acidity in soil, earthquake are prominent. Among these flash flood,
acidity in soil hider cultivation. Because of acidity most of the lands is not cultivable for common
products of Bangladesh such as rice, jute, potato etc. And for flash flood, people of jaintiapur are
not interested to cultivate their own products. So problems are acute in this area.

51
Map-3.1: Affected area of natural hazards in Bangladesh

52
Table 3.2: Disaster of Bangladesh
Issue Pressure / Cause Impacts
Flood
 Excess flow monsoon.
 Improper infrastructural
development.
 92 percent of the total catchment
area across the border.
 Drainage congestion dew to river
bed siltation.
 Deforestation in upper catchment
area.
 Disruption of communication &
livelihood system.
 Loss of agricultural production.
 Disruption of essential services.
 National economic loss.
 Loss of human lives& biodiversity.
Drought
 Less & uneven rainfall in dry season
and wet season.
 Non-availability of water in dry
season.
 Fluctuation of ground water table.
 Loss of agricultural production.
 Stress on national economy due to bad
harvesting.
 Disruption of life style.
 Reduction of fresh water fish
production.
Cyclone &
Storm
surge
 Geographical setting of Bangladesh.
 Coastal configurations bathymetry
of the Bay of Bengal.
 Location of ITCZ near the equator
and its shifting with the apparent
movement of the sun across the Bay.
 Disruption of communication &
livelihood system.
 Damage & destruction of property.
 Environmental degradation.
 Loss of lives & agricultural Production.
Tornado
 Intense ground heating & low level
moisture incursion from the Bay of
Bengal during pre and post
monsoon.
 Conjugation of western disturbance
with locally developed low pressure.
 Loss of lives & biodiversity.
 Destruction of property & damage of
cash crops.
 Damage to essential services.
 National economic loss & loss of
livelihood.
Earthquake
 Geographical location of
Bangladesh having major &
moderate faults.
 Damage & destruction of property.
 Loss of lives & disruption of life style.

53
3.2 Hazards of Study area
A flash flood is a rapid flooding of geomorphic low-lying areas; washes, rivers, dry lakes and
basins. It may be caused by heavy rain associated with a severe thunderstorm, hurricane, tropical
storm or melt-water from ice sheets or snowfield. Flash flood can occur under several types of
conditions. Flash flooding occurs when precipitation falls on saturated soil or dry soil that has poor
absorption ability. Sylhet area mainly sand rich and has poor absorption quality. (Map 3.2) So in
the season of heavy rainfall mainly occurred. Mainly in the time of June and July flash flood occur
in this area. It sustains very short duration but damages are great.
Map 3.2: Flash Flood affected area of Bangladesh
Floods are the most significant natural hazard in the country causing extensive damage to human
life and property. The country lies on the downstream part of three major river basins:
Brahmaputra, Ganges and Meghan and thus is frequently flooded. (Map 3.3) There have been
many destructive floods in Bangladesh, including very severe floods of 1987, 1988 and 1998. The
1988 flood set a new record for flooded area, while 1998 flood was unprecedented with its long
duration. The flood damage potential in Bangladesh is increasing due to the possible causes of
climate change, urban concentration in the three river basins, encroaching of settlements into flood

54
prone areas, and overreliance on the safety provided by flood control works such as levees,
reservoirs. There are two types of floods which occur in Bangladesh: annual floods (barsha) that
inundate up to 20% of the land area; and low frequency floods of high magnitude that inundate
more than 35% of the area (bonna). The major floods that occurred in 1954, 1955, 1974, 1984,
1987, 1988, 1993, 1998, 1999, 2000 and 2007 have been very destructive and caused serious
threat to lives and economy. In the context of human exposure in flood hazard zones, nearly
19,279,960 people are present in these zones and Bangladesh ranks 1st among 162 nations.
Similarly, the modeled amount of GDP in seismically hazardous zones puts Bangladesh 3rd among
162 countries. The investigated area mainly flooded water from Surma River. And this area flooded
every year. So the consequence of flood is severe but they are adaptable by nature with it.
Map3.3: Flood Affected area of Bangladesh

55
In the earthquake zoning map of 1993, 26 percent of Bangladesh falls in high risk, (Map3.4) 38
percent moderate and 36 percent in low risk zone in terms of earthquake vulnerability. The
distribution of recorded earthquakes indicate a major clustering of seismicity around the Dauki
Fault and scattering of other events along other major fault systems of Bangladesh. The magnitude
of the earthquakes are moderate (4-6) and majority of them are shallow depth. The historical
records show that the there have been some major earthquakes in Bangladesh. The 1548
earthquake had affected Sylhet and Chittagong with reports of ground rupture and hydrological
changes. The 1762 earthquake had raised the Foul Island by 2.74 meters and the northwest coast
of Chedua by 6.71 meters above the MSL and had caused permanent submergence of part of
Chittagong. The 1897 Great India earthquake had caused extensive damage to parts of
Mymensingh, Dhaka and Rajshahi. Among the recent major earthquakes, the 1997 Chittagong
earthquake caused extensive damage to the adjacent areas. In the context of human exposure in
seismically hazardous zones, nearly 1,330,958 people are present in these zones and Bangladesh
ranks 17th among 153 nations. Similarly, the modeled amount of GDP in seismically hazardous
zones puts Bangladesh 42nd among 153 countries.
In the context of human exposure in seismically hazardous zones, nearly 1,330,958 people are
present in these zones and Bangladesh ranks 17th among 153 nations. Similarly, the modeled
amount of GDP in seismically hazardous zones puts Bangladesh 42nd among 153 countries.

56
Map-3.4: Seismicity classified in Magnitude in and around Bangladesh
The area is not suitable for the cultivation of land. In rainy season there deposited gravel rock. Then
there soil is acidic. The people of this area use their land only 3/4 month as cultivating crop.
Map: Soil Problem Area of Bangladesh

57
Large and small landslides occur almost every year in nearly all regions of the world. In the past,
landslide was not considered a major hazard in Bangladesh. . Due to heavy rainfall during June,
landslides and collapsed walls caused widespread damages in Chittagong city, Sylhet and other
hilly areas of Bangladesh. Because most of the hilly areas are mainly sandstone rich, and loosely
compacted.Slumping is prominent in jaintiapur and surroundings areas.
There also human induced degradation of environment likes wildland fires, misuse of land, water
and air pollution. Here the viewed important one that various types of gravels are carried out by
stream which is deposited the surface of floodplain causing pressure on. Locallabor withdraw that
a huge which causes subsidence of surface and environmentally it is degradation.
Fig 3.1: Grable withdrawing on surface land.
3.3 Causes of Natural Hazard & Environmental Problem:
Our study area is foot of the shilong platue, when heavy rainfall in Meghalaya then it flows with
strong speed. Flood that covers a huge is occurred after 5/8 years. It over up to 10-15 feet with the
duration about 10 minutes stays at one day. This short time flood sometime is devastating.

58
People of this area mainly foothills clean up vegetation for the cultivation of joom.This one causes
landslide in rainy season. The tribal groups dig hill mouth to set up their built which also could
cause this.
As there is very poor early warning system, people are affected economically and physically so
much. After the flood occurrence there is a crying need for pure water .A lot of sediment about 6
to 8 inches come in rainy season .The area is deposited in flood from Sari to Surma. Local people
cultivate crops only three months from June to August.
The local leader cut plant and hill to make space that they continue their business. For this reason
have a negative impact to environment. They cut hill that make landslide or slumping hazards.
Tamable is an important land port of our country. Stone and Coal are import form this port. Near
this port there have many stone businessman that they cut hill and forest for the place for stone
quarrying. That has a negative impact to our environment. It destroys our Archaeological heritage.
Fig 3.2: Sona Tila Gravels are being crashed

60
Conclusion
Geological survey is concerned chiefly with the systematic geological mapping and
survey of rock and mineral, fossils, oil, gas and water resources of the surface and
subsurface. With the help of field geology, air photography satellite imaging (remote
sensing) and geophysical surveying it particularly puts emphasis on the economic
deposits. Its purpose may also be purely scientific. The geological surveying also
furnishes useful information in foundation studies for road and railway alignments,
for bridges, tunnels and buildings, in town protection works and in Earthquake
hazards. (Banglapedia)
Field geologic survey is the study and interpretation of rocks, the determination and
location of points in a map where observation are made and measurement of the
attitude of beds as well as the study of physical features, structures, lithology,
stratigraphy, geologic history, economic geology and finally the preparation of
geologic maps usually involves the geologic field survey. With the exception of
northeastern and southeastern margins, Bangladesh is covered by a vast Alluvium
plain (Banglapedia). For the training purposes of students field works are confined of
the areas where rocks are outcropping and Jaflong- Tamabil- Lalakhal area of Sylhet
district is one of them. Here the rocks from Middle Eocene to Recent are exposed. The
rocks are disturbed by folding, faulting, joints. The rocks are divided into nine
lithostratigraphic units. The rocks were studied both in the field and in the
laboratory. The rocks were correlated with the other areas of the adjacent territory.
The economic resources of the investigated area were studied.
The field work is done for profiling geophysical hazard and disaster management of
this area. This area mainly face flash flood, earthquake soil acidity etc.

61
Our guide teachers, Dept. and Dean Office tried to give us a best effort to give a
bitter field work. But there have some limitation thus are
1. Base map: Our supplied base map is produced before 1990, so this base map
isn’t place new GPS position. That there make an error
2. Scientific tools and Equipment: As a new Department, our dept. doesn’t
supply available tools and Equipment.
3. Staying Place: Our haven’t any stable staying place. Their hotel isn’t available.
So we stay Dakbanglo, School, college etc. so this place isn’t safe for us
4. Financial: Budget for the field work isn’t proper.
5. Time (4 day) is not enough for this survey.
There have many others limitation such as Transport, Study Materials etc.
Our dept. should be setup a stable staying place that students stay safety. Increase
scientific tools and equipment. Base map should be modernization that match with
our hand GPS. Should be increase fund for field work. I think our teachers done all
things for us that we stay well and done better our next field work.

63
References
 Ahmed, A.: Oligocene stratigraphy and sedimentation in the Surma basin, Bangladesh, M. S. Thesis,
1983.
 Banglapedia.
 Encyclopedia Britannica.
 FEMA
 Evans, P. (1933): Tertiary succession in Assam, than, geol. Inst. India, v-27.
 Evans, p. (1964): The tectonic frame work of Assam, Geol. soc. India, Jour; vol.5, pp – 80 – 85.
 Geological note book wrote during field work.
 Haque, M. 1982: Tectonic setup of Bang and its Relation to Hydrocarbon Accumulation,
Phase-1: Centre for policy Research (D.U), and University Field staff International (UFSI), U.S.A.
 Haque, M. N.: Paleontology of the Tertiary limestone and associated sediments, M. S. Thesis, 1969.
 Hari Prasad Paul (1988): Structure and tectonics of north Eastern part of the Surma Basin, Sylhet, Bang.
M.sc Thesis, Geology Dept. Dhaka University.
 Hiller, K. and Ellahi, M., 1984: Structural development and hydrocarbon entrapment in the
development in the Surma Basin, Bang. (Northwestern Indo – Burman Fold Belt), 5th
offshore South
East Asia conf. session- 6, logging, Singapore.
 Holtrop, J. F. and Keizer, j. (1970): Some aspect of the Stratigraphy and correlation of the Surma
Basin Wells, East Pakistan, ESCAFE minerals Resources Development Series,no.6.
 Imam, M.B, 2005: Mineral Resources of Bangladesh.
 Khan, M.A (1978): Geology of the eastern and north eastern part of sadar subdivision Sylhet district in
Bangladesh. Record of G. S. B. vol.2, part-iv.
 Mathur, L. P. and Evans, P; 1964: Oil in India Inter.Geol. Cong. 22nd Session.
 Monsur M. H.: An Introduction to the Quaternary Geology of Bangladesh. A complimentary research
of IGCP 347. Quaternary Stratigraphic Correlation of the Ganges-Brahmaputra Sediments (1995)
 Saha, S. K.: Stratigraphical and lithoclast analysis of the gravel deposits exposed at Jaintiapur,
Bholaganj, M. S. Thesis.
 Wallid, K. M. (1982): Paleostratigraphy of the Tertiary Sediments as Exposed along the Jaflong
Tamabil road cut section in Sylhet district, Bangladesh. Unpublished M. Sc. Thesis, Geology Dept.
Dhaka University.

65
Appendix-I
List of Map
Map Name Page no
Map 1.1 Location of Jaintiapur 02
Map 1.2 JaintiapurUpazila 03
Map 1.3 Climate map of Bangladesh 08
Map 1.4 Drainage patern of Investigated area 09
Map 2.1 Sylhet Trough and Surrounding Area 20
Map 2.2 Satellite image which represents Regional topography
and stratigraphy of the investigated area
21
Map 3.1 Affected area of natural hazards in Bangladesh 41
Map 3.2 Flash Flood affected area of Bangladesh 43
Map 3.3 Flood Affected area of Bangladesh 44
Map 3.4 Seismicity classified in Magnitude in and around
Bangladesh
45
Map 3.5 Soil Problem Area of Bangladesh 46
List of Table
Table Name Page no
Table 2.1: The Stratigraphic succession of NE Bangladesh, Sylhet
Trough
22
Table 3.2: Disaster of Bangladesh 42
44

66
List of Figure
Figure Name Page no
Fig 1.1 Discussion with local people knowing about Hazards 06
Fig 1.2 Seminar on Citrus Research Center 07
Fig 1.3 Sari River 09
Fig 1.4 Sari River 10
Fig 1.5 Rangapani River 11
Fig 1.6 Noyagoan River 11
Fig 1.7 Vegetation near Shari River 13
Fig 1.8 Citrus Recherche Center plant (BARI Kamala -1) 14
Fig 1.9 Recherché Plant in Citrus Recherce Center 14
Fig 2.1 Upliftment of Himalayas due to collision of Indian plate
and Eurasian plate
16
Fig 2.1 3D simulation of the Bengal Basin 18
Fig 2.3 Outcrop of Sylhet Lymestone 24
Fig 2.4 Fault Bractia, Dauki Fault 24
Fig 2.5 Sudden Topographic change due to Dauki Fault 25
Fig 2.6 Contract Between Kopili Shale and Sylhet Lymestone 25
Fig 2.7 Outcrop ofKopili Shale 26
Fig 2.8 Iron Rich Barail Sandstone 27
Fig 2.9 Corse Bedding Lamination in Barail Sandstone 28
Fig 2.10 Contract between Surma and Tipam Sandstone 29
Fig 2.11 Lenticular Beding in Surma Group 30

67
Figure Name Page no
Fig 2.12 FoldingOutcrop of Shale (Surma Group) 30
Fig 2.13 Drag fold in Surma Group in Nayagang 31
Fig 2.14 Laterite Bed over Tipam Sandstone 32
Fig 2.15 Clay Gol in Tipam Sandstone 32
Fig 2.16 Tipam Sandstone 33
Fig 2.17 Conglomerate on Tipam Sandstone 33
Fig 2.18 Outcrop of Girujan Clay 34
Fig 2.19 Outcrop of Dupitila Formation 35
Fig 2.20 Cross bedding in (Dupitila Formation 36
Fig 2.2.1 Outcrop of Dihing Formation (Beside our Base Camp) 37
Fig 3.1 Grable withdrawing on surface land. 47
Fig 3.2 Sona Tila Gravels are being crashed 48

68
Appendix II
Day Stop. Latitude Longitude Attitude of Beds
1
Camp 25°08ʹ4.9˝ N 92°07ʹ45.5˝ E
1 25°05ʹ46.4˝ N 92°07ʹ03.3˝ E 78°, SE; 262
2 25°05ʹ49˝ N 92°07ʹ07.4˝ E
3 25°05ʹ55.8˝ N 92°08ʹ39.3˝ E 270; S; 55
4 25°05ʹ54.3˝ N 92°08ʹ4.4˝ E
5 25°06ʹ37.3˝ N 92°09ʹ06.8˝ E
2
1 25°06ʹ20.9˝ N 92°10ʹ32.2˝ E
2 25°06ʹ33.7˝ N 92°10ʹ42.1˝ E 120; SW; 70
3 25°06ʹ05˝ N 92°1033.7˝ E
4 25°06ʹ55˝ N 92°10ʹ55.7˝ E
5 25°06ʹ44.0˝ N 92°10ʹ49.1˝ E 298; SW; 56
3
1 25°08ʹ05.3˝ N 92°07ʹ45.3˝ E ; 264; SW; 35
2 25°08ʹ20.6˝ N 92°08ʹ08.8˝ E
3 25°08ʹ39.3˝ N 92°07ʹ47.6˝ E
4 25°08ʹ55.9˝ N 92°07ʹ33.3˝ E 280; SW; 34
5 25°08ʹ24.4˝ N 92°07ʹ17.9˝ E 264; SE; 44
6 25°10ʹ37.3˝ N 92°04ʹ35.7˝ E 248°, NW; 18°
7 25°10ʹ4.9˝ N 92°04ʹ21.77˝ E
8 25°10ʹ42.5˝ N 92°04ʹ29.5˝ E 110; NEW; 17
9 25°10ʹ34.3˝ N 92°03ʹ44˝ E 246°, SE; 18°
10 25°10ʹ51.6˝ N 92°01ʹ59.9˝ E 276; NE; 20
11 25°10ʹ43.2˝ N 92°01ʹ38.9˝ E
4
1 25°10ʹ34.9˝ N 92°01ʹ33.6˝ E 280; NE; 20
2 25°1043.4˝ N 92°0ʹ55.3˝ E 280; SE; 37
3 25°10ʹ53.5˝ N 92°01ʹ05.5˝ E 227°, SE; 28°
4 25°08ʹ15.6˝ N 92°08ʹ06.3˝ E 58°, S20°E; 59°, S32°E

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