EARTH SCIENCES FIELD WORK ALONG JAINTIAPUR - TAMABIL – JAFLONG SECTION; SYLHET, BANGLADESH.

May, 2014
Report submittedby
MD. RAISUL ISLAM SHAMRAT
EXAM ROLL: 308
SESSION: 2012-13
DEPT. OF DISASTER SCIENCE & MANAGEMENT
FACULTY OF EARTH & ENVIRONMENTAL SCIENCEs
U uNIVERSITY OF DHAKA
EARTH SCIENCES FIELD WORK ALONG
JAINTIAPUR - TAMABIL – JAFLONG SECTION;
SYLHET, BANGLADESH.
REPORT SUBMITTED IN REQUIRMENT OF PARTIAL
FULFILMENT OF THE SYLLABUS FOR 1ST YEAR B.S. (HONS)
IN DISASTER SCIENCE AND MAMAGEMENT.

Abstract
The area of investigation is situated in the north eastern part of Surma Basin and
tectonically belongs to the south Shillong Shelf zone of the Western platform
flank of the Bengal foredeep, a major tectonic element of Bengal Basin. This
report deals with the findings of geologic investigation carried out in Jaintiapur
and the adjoining areas of Sylhet district. The area lies in between 250
05’46.4”N
to 250
10’54.9”N latitude and 920
0’55.3”E to 920
11’ 14.8”E longitude.
The area is developed by a Faulted Anticline structure. The general trend of the
studied area is more or less east-west along the foothills of Khashi-Jaintia hill
range and the bed dips both south and north. The area constituted a part of large
east west trending fault Dauki fault. Sharp escarpments and structurally
controlled consequent rivers are the direct indicative of fault. A regional
unconformity between Barail and Surma is evidenced by the presence of laterite
band. Moreover horizontally deposited gravel beds (Uzaninagar & Sonatila gravel
beds) make angular unconformity with the inclined Tertiary strata.
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) and Alluvium. Sonatila Gravel bed overlies Barail and Surma group. 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 deposition of the sediments took place in shallow marine to continental
environment under fluvial energy environment condition. Frequent and rapid
change of facies is reflected by the consequent change of lithology.

Many types of hazard occur in the study area and nearby areas in pre-monsoon
season like- landslide, flash flood etc. That affected agriculture & nearby locality.
Though minor scale of hazard was occur in the study area.
There is no prospect of very significant mineral deposits as seen by this geological
study. However the investigated area has limited commercially exploitable
deposits. Large amount of gravels carried by the rivers are economically valuable.
Moreover it is to be mentioned that the adjoining areas have high prospect for
hydrocarbon exploration.

CHAPTER- 1:
INTRODUCTION
1.1 Location, extents & access
1.2 Objective, purposes & scope
1.3 Methodology
1.4 Demography & culture
1.5 Climate & weather
1.6 Drainage and water supply
1.7 Soil & agricultural condition of study area

11.1: Location, Extent & Access
The studied area lies on the southern foothills of Khashi-Jaintia ranges of Meghalaya and in
between latitude 250 5/46.4// N to 250 10/54.9// N and longitude 9200/53.3// E to 920 11/
14.8// E. This area is covered in the survey of Bangladesh Toposheet number 83 C/4 in scale
1:50,000. The area belongs to the Jaintiapur Thana and is about 45 km away from Sylhet
town in northeastern direction.
The area is limited in the north by Khashi-Jaintia hill range of Meghalaya, in the south by the
Shari River in the west of Dauki River and in the east of Lalakhal area. The area comprises
southern faulted block of Shilong plateau and includes Tamabil-Jaflong-Afifanagar, Sripur
and Jaintiapur. The total area is about 160.40 sq. km. Where 24.48 km. in the east west
direction from Lalakhal to Dauki River and 6.53 km. in the north-south direction from
Meghalaya-Bangladesh border to the Sharighat
As Sylhet is one of the important districts of Bangladesh, its internal and external
communication system is comparatively better than many other districts. However, it is well
connected with Dhaka by road, railway and by air (Map-1.1). The investigated area that is
Jaintiapur is well linked with Sylhet city and it is on the way of Sylhet-Jaflong metalloid road
(Map-1.2) and its local communication is maintained mainly by footpaths, rickshaw and also
by boat.
The Dauki River bank was accessible by motor vehicles and then footpaths. Nayagang
section and Hari River section are connected with Jaintiapur by metalloid road and this
section is accessible by foot track and river bank. The metalloid road goes up to Jaflong
through Sripur and Tamabil. Afifanagar are accessible firstly by motor vehicle and then foot
track, there also go by boat in the Shari River.

Map 1.1: Location Map of Jaintiapur, Sylhet

Map 1.2: Upazila map of Jaintiapur, Sylhet.

1.2: Objective, purpose & scope
The field work was carried out by the students of 1st year B.Sc. (Hons) at Jaintiapur in Sylhet
District to fulfill a half unit course (DSMHF-115) of earth sciences Field work. Though
Bangladesh as a whole is not so suitable for all geological investigations, but her
northeastern and southern parts offer excellent opportunity for noticeable geological
investigations in sedimentary rocks (because there is no exposed igneous and metamorphic
rocks in Bangladesh). Jaintiapur and its adjacent areas which are in the northeastern part of
Bangladesh can be regarded as museum of geology for entire Tertiary and Quaternary
succession of the basin is exposed in this region.
But the main purpose of the field trip was to acquire the knowledge of the methods and
techniques of field investigations, to compare the practical situation of studied theoretical
problems, to familiarize with a field geologist's life and finally to construct a geological map
of the studied area providing all the information gathered during the field work. Our
purpose also includes the construction of a stratigraphic succession of the area,
Determination of lithology and sedimentary structures, systematic sampling and analyzing in
lab, Study of major structures and other structural features, Interpretation of the geologic
history of the area, Hazard & environmental problem analysis and also form a suitable cross
section from the constructed geologic map that interprets the structure, lithology and
sedimentation of the area.
It has been proved very much suitable to fulfill the mentioned purposes and comprises
numerous road cut and stream cut section offered excellent exposures through which the
necessary investigations can be carried out easily. It also offered to realize many kinds of
hazard like landslide, flash flood, flood, earthquake etc.
It is to note that although the investigated area offered very good scope, to study properly
the time schedule was very short, very detail investigations were not possible.

1.3: methodology
When our team investigated an area, we apply some methods. For applying these methods
we use some object. We applied these methods by sequel. That method was helping us to
investigate the area perfectly. How we applied these methods is given blew in a flow chart.
Field Investigation Method
The investigations were carried out in the field by adopting the usual ‘Traverse method’ that
is walking on foot through the road cut and stream cut sections with the common
instruments used by a geologist in the field.
1.
• Taking Location and Bearing
2.
• The Lithologic Investigation
3.
• Structural Investigation
4.
• Messuring atitude of bed, dip direction, dip angle etc.
5.
• Collecting Samples
6.
• Tacking Photographs
7.
• Hazard Investigation
8.
• Construction of Geological Map

Other necessary things generally used during a journey. However, the detail investigations
were carried out as follows:
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
Attitudes of the beds were measured by the clinometer and for the rough, disturbed and
vegetated 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.
Hazard identification
The real view picture taking & observed the hardness of rock also the infrastructure system
of the local area easily understand about hazard. We also interview some local people to
investigate hazard by using hazard identification system.(Fig-1.1)
N
However it is to note that, the whole investigations were carried out by the help of our
respectable teachers with proper guiding who were in the team in every day work.

Fig1.1: Hazard investigation by a local people
1.4: Demography and Culture
The area is moderately populated. The lifestyle of these people are not so easy, they are
living along the foot of the hills and in plain land. These people are socially and economically
undeveloped. They have no adequate facilities of civilization. Their education rate is 21%.
Agriculture is the main profession of the people. Some people are employed in the gardens,
trades and commerce, government service, teaching and in private agencies. A small
number of people are also engaged in fishing A little percentage of the population is
employed in government services. The area is a peculiar place of mixed socio – religious
culture. The original local people are called “Khasia”. The majority of the people are Muslim.
The minority includes the Hindus and the Buddhists. It the tea gardens, there are some
Oriyas Bunas, Nunayas and other people from the Choto Nagpur Plateau, India were
brought in before 1947 and have settled here (Khan,1978).
The people of investigated area have the culture almost similar to the other parts of
Bangladesh, except the tribal people, they have their own culture. The people in this area
have their culture according to their respective religion. Hindus influenced the culture of the
area during the region of Jaintia raja, remnant of which is Megalithic stone. So this area has
a long historical background. Once upon a time Jaintiapur was a part of Oohomia Promilla-
Empire of Assam.(Banglapedia)

1.5: Weather & climate
Because of geological location, the investigated area
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.
The average range of annual temperature, humidity and rainfall of the area ranges from 900f
to 65f, 36% to 99% and 300 cm to 380 cm respectively. Climate map of whole Bangladesh is
given below.(Map-1.3)

Map 1.3: Climate map of Bangladesh

1.6 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.
Map 1.6: 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 1.2) which acts as the main source of water distribution of the eastern
portion of the area originates in khasia Jainta 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.
Figure1.2: Sari River
Among the mentioned four rivers, the Dauki (Fig 1.3) 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.

Fig1.3: Dauki River
The two main tributaries of the Shari River, namely the Nayagang(Fig 1.4) and Rangapani(Fig
1.5) 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.

Fig1.4: Rangapani River
Figure 1.5: Noyagoan River

1.7: Soil & agricultural condition of study area the tropical
to subtropical climate. But as the influence of the humid north-eastern monsoon wind over
The investigated area falls under humid tropical to sub-tropical climatic conditions. This
climate encourages the growth of lush orchids. The area is susceptible to heavy monsoon
rains resulting in the periodical flooding of the plains.
Investigated areas soil is mainly acidic. It is about 4.5-4.8 PH . Rainfall is 6ooo mm per year.
And soil is also sandy clay type.
The hilly areas have forest and in places it is matted by thick undergrowth. The thick
vegetation occupies the hillocks and slopes. Shimul, Champa, Chapalish. Teak Betel nut etc
are the important trees of the investigated area. High precipitation with sufficient heat
favors the luxuriant growth of this tropical evergreen forest. The plain land of the
investigated area is covered with nalkhagra and grasses. Plain lands support cultivation.
Paddy and varieties of vegetables are the chief agricultural products of the area. Pineapple
gardens are scattered in the area. Tea gardens are abundant in the hill slopes (fig 1.6).
Banana and Guava trees are available in this area.
Figure 1.6: Tea garden in hill slope in Afifanagar.

Cultivation of the area is generally carried out in the hill slopes, valleys and in the associated
plain lands. About 63,923 acres of land is cultivable here. Rice is the principal crop of the
area. Tea is the main cash crop off the area and tea gardens abound on the hill slopes.
Orange and pineapple gardens are scatterlly present throughout the area. A huge amount of
land is used for watermelon cultivation every year. Besides these various seasonal crops like
paddy, tobacco, oilseeds and vegetables are also widely cultivated here. There have a citrus
Centre which is only one in Bangladesh. (fig -1.7 & 1.8)
Figure 1.7: Citrus Research Center plant.

Figure 1.8: Citrus Research Center plant.
Many type of hazard like flash flood, land slide, floods etc. disturb to cultivate crops. Water
is the main problem on that area to agriculture in the winter.

CHAPTER- 2:
Geology of the study area
2.1 Tectonic evaluation of Bangle basin
2.2 General stratigraphy of sylhet
2.3 Lithological description of investigated formation 2
2 2.3.1 Sylhet limestone2
2.3.2 Kopili shale2
2.3.3 Barail group2
2.3.4 Surma group2
2 2.3.5 Tipam Group2
2 2.3.5.1 Tipam Sandstone 2
2. 2.3.5.2 Girujan Clay
2.3.6 Dupitila formationd
2 2.3.7 Dihing Formation
2.3.8 Alluvium

2.1: Tectonic evolution of Bengal basin
Bengal Basin covers entire Bangladesh, part of West Bengal, Tripura, Monipur, Mizoram
states of India and parts of the north-western Burma. The interpretation of the tectonics of
this basin has been suffering from both over simplification and over complification. The
Bengal basin is the result of prominent mantle up warping, intercontinental break, newly
created oceanic crust and its convergence at the previously stable continental margin of
miogeoclinal character.
For the details study of Bengal basin we must go back to the pale tectonics of India. India
has been separated from Australia along a pale continental shelf by the process of mantle
activated rift. The initial breakup of the Gondwana land occurred in the Early Cretaceous
time with separation of India from combined Australia and Antarctica northerly direction.
New sea floor was created what is now the Bay of Bengal and sea floor that has subducted
beneath the Sunda Arc. The northward flight of the Indian plate was maintained along two
driving lines, which are over fracture zone and 90˚E Ridge transform. The magnetic anomaly
numbers on the western side of the 90˚E Ridge transform is the indication of NNE motion of
the crustal segment of this region. The 90˚E transform became ridge due to massive
intrusion of magma from the hot spot located near Gulf of Cambay (Bose 1973). It is
believed that Chaqos Laccadive Ridge is related to Deccan volcanism and is the extension of
Western Ghat Fault of India.
The Bengal Basin started originating as the oceanic crust (Indian plate) converged beneath
the Burmese plate. Tectonically Bengal Basin could be divided into two margins:
a. Active margins
b. Passive margins.
Passive margin is characterized by Moho up warping. It has the following parts:
NSP-Northern slope platform
SP- Stable platform (Buried ridge)
NGH- Nawabganj Gaibandha high (Buried ridge)
JH- Jaripur high
SSP- Southern part of platform
Hinge zone- Characterized by series of down to the basinal thrust faults.

The platform flank comprises series of horsts and gravens of Gondwana period and
northward slopping basement flanking the Sub-Himalayan Foredeep.
Active margin is characterized by the deeper basin. It contains Sylhet trough, Faridpur
trough, Hatia trough zone of elevated oceanic crust (Barisal-Chadpur gravity high) and
Eastern Tertiary Folded Belt Which were formed due to the migration of detachment zone
again and again of the obducted Burmese and subducted Indian plate. There is a trend TT3
along which the folded belt abruptly changes the topography and forms a trough again.
Near the Dauki fault a homoclinal fold is formed by the dragging effect of this mega fault. All
the anticlines and synclines of the folded belt have a trend due E-W. There are some other
E-W trending small folds near the Jaintiapur area, Sylhet that was also due to dragging effect
of Dauki fault.
Whole Bengal basin is separated by two distinct crustal domains along a paleocontinental
margin, almost passing in a NNE-SSW direction. The north and northwest domain of the
margin including part of Sylhet trough is underlain by the continental crust whereas the
south and southern domain including Faridpur and Hatia troughs underlain by the oceanic
crust.
The sedimentation of Bengal basin was characterized by Assamese Gulf and Burmese Gulf.
Assamese Gulf carried the sediments of Himalayan and Burmese Gulf carried the sediments
of Arakan-Yoma. Bengal basin is the one of the thickest sedimentary basins of the world.
The initial collision between India and Eurasian plate occurred in the Late Paleocene time.
This was a time of change in relative plate motion in the entire Indian Ocean. The Eocene
limestone then deposited along entire continental shelf of northeast India. The back-arc
basin is represented by Central Burma or Irrawaddy basin and fore-arc basin is represented
by Arakan-Yoma Folded Belt and its western extension up to Chittagong-Tripura Hills.
According to Brunnschweiler (1974) thick sediments were deposited during Mio-Pleistocene
in Irrawaddy Basin with the interception of the convergence of Indian plate and the Tertiary
sediments deposited in the fore-arc basin, the region was uplifted during Miocene orogeny
and followed by Pleistocene Orogeny to form the present Arakan-Yoma mega-anticlinorium
and its western extension covering Chittagong-Tripura Folded Belt.
The Bengal Basin can be divided in to 3 geo-tectonic provinces (figure 2.1):
(1) The Stable Shelf;
(2) The Central Deep Basin (extending from the Sylhet Trough in the northeast towards the
Hatia Trough in the south) and
(3) The Chittagong-Tripura Fold Belt.

Figure 2.1: Geo-tectonic provinces of the Bengal Basin
The Basin has evolved from collision of the Indian Plate with the Eurasian Plate. According
to Plate tectonic theory, the north western part of Bangladesh (Bogra-Rangpur-Dinajpur area)
was initially joined along with Indian landmass, with Antarctica, Australia and others
forming a vast super continent named Gondwana far in the southern hemisphere. Rest of the
landmass of Bangladesh i.e. the southeastern part did not exist at that time. The Paleo-
Continent (Pangea) broke down through the passage of time creating current continents (fig-
2.2).
After Precambrian peneplanation (Process of the formation of a low-relief plain representing
the final stage of fluvial erosion during times of extended tectonic stability known as
peneplain) of the Indian Shield, sedimentation in the Bengal Basin started in isolated graben-
controlled basins on the basement. With the breakup of Gondwanaland in the Jurassic and
Cretaceous, and northward movement of the Indian Plate, the basin started down warping in
the Early Cretaceous and sedimentation started on the stable shelf and deep basin; and since
then sedimentation has been continuous for most of the basin.
Subsidence of the basin can be attributed to differential adjustments of the crust, collision
with the various elements of south Asia, and uplift of the eastern Himalayas and the Indo-
Burman Ranges. Movements along several well-established faults were initiated following
the breakup of Gondwanaland and during down warping in the Cretaceous.

Figure 2.2: Upliftment of Himalayas due to collision of Indian plate and
Eurasian plate.
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 (figure 2.3).
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 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, Curray, Chowdhury, &
Gani, 2003)

Figure 2.3: 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. 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: general stratigraphy of ne sylhet, Bangladesh
The study area is underlain in part by Holocene and flood plain deposits and in part by
deformed Tertiary sediments. The Shari River has exposed excellent section of outcrops of
strata deposited from Oligocene to Pleistocene. The Eocene aged strata have been exposed
by the Dauki fault. A satellite image of the studied area to show the position of outcrops in
the study area is given below. (figure 2.5)
Table 01: Stratigraphic Succession of the NE Sylhet
[Paul, [paul,1988 and field investigation]

Map 2.4: Satellite image which represents Regional topography and
stratigraphy of the investigated area.
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.
Sylhet limestone
Kopili shale
Barail sandstone
Surma group
Tipam sandstone
Girujan clay
DupiTila formation
Dihing formation
Alluvium

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 description of investigated formation
The oldest rock exposed in Bangladesh is Tura Sandstone of Early Eocene age in Takerghat
area in Sunamganj district in Sylhet division. But this are not found in our investigated area.
The Sylhet Limestone Formation is the oldest rock exposed 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.
2.3.1: Sylhet Limestone
The term “Sylhet limestone” as a rock unit was first used by Khan (1963).The formation is
exposed on the left bank of the Pian River near the Bangladesh-Meghalaya border, the only
outcrop of Banngladesh. Found jointed limestone bed (sub vertically) . That is highly
fossiliferous. It is also the oldest (Eocene) rock of the investigated area.
The grey, fossiliferous Limestone offers a variety of fossils from disk shaped Discosyclina
(fig-2.4) to elongate lens shaped Nummulites. The hard limestone is highly jointed and
fractured. The limestone (fig- 2.5) occurs due to large Dauki Fault. The assemblages of
dominantly large microfossils indicate a shallow water, continental shelf zone and a clear
water environment is also documented by total lack of plank tonic remains(Sarwar,1679).

Figure 2.4: Fossiliferous Limestone
Figure 2.5: Contract Between Kopili Shale and highly gointed Sylhet
Lymestone
Kopili shaleSylhet limestone

A fault found in our investigated area. Due to the Dauki fault Sylhet limestone is
characterized by hot & humid climate, huge organic material, calm & quiet environment. It
indicates the end of past environment. An anther criterion is sudden change of elevation
(about 5km). Sonatila gravel bed (Dihing formation) is over sylhet lime stone. Fault breccias
and Kopili shale created by Dauki fault in Jaflong (fig-2.6). Its direction is anomalous like-
south east, south west, north west etc. And dip angle is 100-400.
Figure 2.6: Fault breccias and Kopili shale created by Dauki fault in Jaflong.
Though much work had not been done in the area, the similarity of nummulites assemblage
with the Eocene of Garo Hills and Assam makes it likely that this unit is of Middle Eocene
age.
2.3.2: Kopili Shale
The name of Kopili shale was given by Evans (1932) to the beds forming the upper stage of
the Jaintia group after the Kopili river of Garo Hill in India.

It gives a minor outcrop only on the west bank of the Rangapani River (fig- 2.7 & 2.7). It is
dark gray to black colored, very much fissile, thickly bedded to paper laminated, highly
jointed shale. Inter bedded sandstone with argillaceous matrix is present. It is conformably
overlain on the Sylhet limestone. Base of the Kopili shale is not seen. The top of the Kopili
shale are exposed beside Rangapani River in Sripur tea garden. It also found on the east
bank of the Dauki River near the Bangladesh-Meghalaya border. Fossil evidence suggests
that the Kopili shale is of late Eocene age (Evans 1932).
Figure 2.7: Outcrop of Kopili Shale

Figure 2.8: Outcrop of Kopili Shale
In Tamabil latitude 25010/51.6// N & longitude 92001/59.9//E Barail group is on Kopili shale.
Near forest department of Jaflong, older kopili shale is to words axis. Theirs missing of
formational bed. Kopili shale & sylhet lime stone is present but Tura sand stone is absent.
There found anomalous dip direction 00-300. In nearby of latitude 25010/42.3// & longitude
92004/29.5// most probably found 00-10 dip angle. Dauki fault is found in kopili shale. Due to
dauki fault some tropographical change is occur.(fig-2.9)

Figure 2.9: Topographic change due to Dauki fault.
Gypsum mineral is found in Kopili shale which indicates sea level regression. (fig-2.10) 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.
Dauki fault
Shilong plateau
Sylhet trough

Figure 2.10: collected Gypsum in kopili shale.
2.3.3: Barail Group
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 exposed in Mahishmara, Sonatila and near Sripur
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 Surma group . In Bangladesh most of
the Barail is deeply buried which outcrops in between Jaintiapur in the East and the Dauki Nala
in the west was described by M.A.M. Khan(1978) as Jenum formation.
Top of this formation is exposed in Stop-4(Lat N250
0839.3 long 920
0747.6)
Strike direction of this bed is  110, Deep Direction N-E and Deep amount  17

The river Nayaganj and exposures along the Jaintiapur - Tamabil road provide a fairly good
section of the Jenum formation which is composed of sandstone, siltstone and silty shale. The
sandstone is mainly pink in colour, weathered to light yeloow and grey, very fine to medium
grained and thin to thick bedded 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.
The upper unconformity boundary between Bhuban and Barail group is represented by two thin
bands a Lateritic conglomerate containing which is well exposed in the Nayaganj river section
and also on the hilltops and slopes of the hillocks. Laterite blocks are normally formed on the
surface of iron rich residual deposits. It is porous, reddish brown colour, has a hard protective
ferruginous incrustation on the exposed surface, which is generally irregular and rough.
Sometimes it is pisolitic which have a concentric structure and are cemented together by
ferruginous and clay minerals. The vesicles of Laterite are filled up with secondary
minerals.Thickness of two part of Barail formation Renji and Jenam.
The lithologic characters that diagnose the unit such as pinkish color, fine to very fine grain, very
well sorting, being hard to moderately hard and its sequential position that is uncomfortably
under lain by kopili formation, suggest the unit to be of Barail group of Oligocene time. M.A.M.
Khan (1978) assigned it as Jenum formation. But defining it as an araneceous unit Reimann
(1983) designated it as Renji formation on the basis of lithology and fossil content of the exposed
rocks. Findings of our observations suggest correlating this unit with the Renji formation of
Assam basin
Barail Sandstone reflects a delta to near shore environment. During Oligocene Himalayan began
to rise 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.

Figure 2.11: Outcrop of Barail Formation
Fig 2.12: Outcrop of Barail Formation

Figure 2.13: latrite bed in Barail Formation
2.3.4: Surma Group
The Surma Group has been named after the Surma series of Assam, India (Evans 1932). The
sediment of the Surma group unconformably overlies the Barail Group. Good exposures of
this unit were observed in the east of Jaintiapur and in the Shari River. The change from the
Barail Group to the Surma Group rather sharp and is marked by the decrease of the
interbedded sandstone in shale and siltstones and the general predominance of argillaceous
material. The Surma Group is made up of bedded, laminated siltstone, shale, silty shale, clay
stone and sandstone found in Surma Sandstone in Afifanagar. Although some sandy shales
are also present. Here mud clast is found. Shale of this unit is profusely jointed and
fractured and even small fault were observed in Tetulghat. It is also exposed near
Afifanagar, Jaintiapur. Most of the sediments are covered by recent alluvium. The dip
direction of the beds of this formation is south-west and the amount of dip ranges from 42°
to 48°.

It is composed of yellowish gray sandstone, bluish gray shale, sandy shale, and siltstone.
Sandstone is fine to medium grained, sub angular and moderately sorted. The sandstone is
hard and is resistant to weathering and forms the cliffs. It shows micro cross lamination,
lamination, trough cross bedding and wavy bedding.
The shale is bluish gray in colour and weathered to gray and yellowish gray. The shale is well
laminated, hard and jointed.
The Surma Group is generally subdivided into two formations namely the Bhuban and the
Bokabil but in the field it is difficult to distinguish between the two units and there
subdivision becomes impractical. The contact of Surma Group with the overlying Tipam
Formation is conformable. The Surma Group is overlain unconformably by Dihing Formation
at latitude 25°08/5.3//N & longitude 92°07/45.3//E. The contact between Surma Group and
Tipam Sandstone found in Afifanagar (fig-2.14).
Figure 2.14: Contact between Surma Group and Tipam Sandstone
found in Afifanagar

2.3.5: Tipam Group
The Tipam Group has been named after the Tipam Series (Mallet, F.R., 1876) given after the
Dihing River in Assam, India. The Tipam Group is subdivided into two formations from
younger to older- the Girujan Clay & the Tipam sand Stone.
2.3.5.1: Tipam Sandstone
The name has been used after the Tipam hills in Assam, India (Mallet 1876). The formation
constitutes the lower part of Tipam Group and is conformably overlain by Girujan Clay and
the contact found in the left bank of the Shari River is gradual. The river Shari gives an
excellent exposure.
The top of Tipam Sandstone Formation form a conformable contact with the Girujan Clay
Formation is exposed at latitude 25°06/23.6//, longitude 92°08/57.2// in the right bank of
Shari River where it consists of alternation of usually bedded to thick bedded and also
laminated (fig- 2.15), fine sandstone and mudstone.
Figure 2.15: Parallel laminated Tipam sandstone beside Shari River

The base of Tipam Sandstone is exposed also in the Shari river bank conformably overlying
the Surma Group at the at 1st day, stop-5 (25°06/37.3//N latitude, 92°09/6.8//E longitude)
where it consists of yellowish brown, medium to fine grained sandstone. Overall lithology
of Tipam Sandstone consists of yellowish brown in colour, fine to mediumgrained, cross
bedded, and massive sandstone, lamination, minor scale of fault (fig-2.16).
Fig: 2.16: Minor Fault in right bank of sari river, Tipam Sandstone
Intercalations of gray shale, conglomerate horizons, pebbles, laterite bed, mud ball (fig-
2.17), wood fragments and petrified trunks(fig-18), coal lenses also occur. Tipam sand stone
& Surma group contact exposed in the left bank side of Sari river (opposite side of Sari
River).
Fault line

Figure 2.17: Clay gall in Tipam Sandstone
Figure 2.18: Petrified trunk occurred in Tipam sandstone.

2.3.5.2: Girujan clay
The name has been given after the Girujan Clay stage of Tipam Series in Assam, India
(Mallet 1876). Top of this formation is exposed at latitude 25°05/54.3//, longitude
92°08/44.4//E by the right bank of Shari River having a conformable contact with the
overlying DupiTila Formation and base of this formation is exposed(Fig-2.19) having a
conformable contact with the underlying Tipam Sandstone Formation. The formation
develops conformably and gradationally from the underlying Tipam Sandstone Formation. It
entirely consists mainly of gray to bluish gray clay and mottled clay (Fig-2.20).
Figure 2.19: Contact between Girujan Clay (Left) and Dupi Tila
Sandstone (Right) found East bank of Shari River

Figure 2.20: Mottled Girujan Clay
2.3.6: Dupitila Formation
The Dupi Gaon is the Type locality of the Dupitila Formation. The formation is exposed
latitude 25°05’46.4”N, longitude 92°07’04.3”E at western part of Dupitila around 200m
north from Sari river behind the Sharighat Primary school. Lithology of Dupitila is yellowish
brown, light gray in colour. Grain size is fine to medium. Sand stone with alteration of clay
stone & silt stone is present in here. Occasionally it characterized by iron incrustation.
Slumping is common high in north. So true bedding is difficult to find. There’s high amount
of vegetation. So the soil is well compacted. Weathering product is not much. yellowish
brown, pink, whitish grey, dark grey & pinkish colour is found. Occasionally present parallel
laminated sedimentary structure. That indicates fluvial environment. Organic material is
present.(fig-2.21) Claygall, which isolated in sand stone, indicates river bank deposits. . At
latitude 25°05’54.3”N, longitude 92°08’44.4”E, right bank side of sari river, here contact
between Dupitila & Girujan clay. Found cross bedding lamination. (Fig-2.22)
Except fossil wood no other fossils are identified in DupiTila Formation. In Assam it is
considered to be Mio-Pliocene in age (Lexique, 1957).

Figure 2.21: outcrop of DupiTila sandstone
Fig 2.22: Cross bedding in right bank of sari river, Dupitila Formation

2.3.7: Dihing Formation
The Dihing formation of Pleistocene age has unconformable contact with the Surma Group
at latitude 25°08’5.3.”N, longitude 92°07’45.3”E, Uzaninagar. It’s gravel is sub rounded to
rounded& gravel size is mainly cobble & pebble. Most of sandstone, others are quartzite,
granite, quartz are present in Dihing formation.(fig.2.23)
Figure 2.23: Boulder bed of Dihing formation

2.3.8 Alluvium
Unconsolidated, loose material brought down by rivers and deposited in its beds of alluvial
fans or weathered material. Alluvium consists of sand, silt, clay in various proportions. River
born alluvium are mainly sand, coarse grained material and weathered alluvium are consists
mostly of clay and silt. They cover various rock formations unconformably and of recent in
age. Mud crack found in Allvium.(Fig -2.24)
Figure 2.24- Mud crack in Alluvium

CHAPTER-3:
HAZARD & ENVIRONMENTAL PROBLEM OFTHE STUDY AREA
3.1 Overview of Hazards in Bangladesh
3.2 Hazards in study area
3.3 Causes of natural hazards & environmental problems

3.1: Overview of Hazards in Bangladesh
Bangladesh is a South Asian developing country. This country is often known as the country
of natural 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 a
another problem in globaly and tis is severe in South asia and as well as in Bangladesh. Some
hazard that occurs in Bangladesh, cause & impacts of that’s given below by a table.

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.
National economic loss.
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.

Map-3.1: Affected area of natural hazards in Bangladesh

In the earthquake zoning map of 1993, 26 percent of Bangladesh falls in high risk, 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.
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 Meghna and thus is frequently flooded. 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 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.

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 & loosely compacted. Slumping is prominent in jaintiapur and surroundings
areas.
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. So in the season of heavy rainfall mainly occurred. Mainly in the time of
June and July flash flood occur in this area. It sustain very short duration but damages are
great.
There also human induced degradation of environment likes wild land 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. Local
labor withdraw that a huge which causes subsidence of surface and environmentally it is
degradation.
Figure-3.1: Gravel withdrawing at Rangapani river

3.2 Hazards in study area
Sylhet is our study which is mainly affected by geophysical, hydro-meterological,
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 land are not cultiable 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.
The Sylhet trough is an undulated terrain because of the Indo-Burman fold belt. It has a thick
layer of Mesozoic and Cenozoic deposits. Some natural and irrational activities of inhabitants
can be seen as hazards of the area.The main hazards of the study area that were investigated
are flash floods, earthquakes, deforestation, stone quarrying, landslides, mudslides, acidic
soil, etc.
3.3 Causes of Natural Hazards and Environmental Problems
Flash flood is the most common hazard of the studied area. Due to the Ridge and Valley
topography, the area is easily affected by flash floods during the times of high rainfall every
year. It generally occurs in the studied area during the months June-August. Huge amount of
water flows from the high areas of India to flood the lowlands. The area becomes flooded in
about ten minutes. Flood water height is about 4-5 feet. In spite of the water going down in
no more than one day the crops are badly affected. The areas near Lalakhal are more affected.
Areas near Indian borders are affected too. (figure 3.2)

Figure 3.2: These areas are ravaged by flash floods during the times of
heavy rainfall. Picture was taken near Gouri-Shankar village, close to Indian
border.
The presence of the Indo-Burman fold belt and more importantly Dauki fault is reason for
the occurrence of earthquakes in the region. Earthquake is a hazard the occurrence of which
usually cannot be foretold. Though earthquakes of high magnitude have occurred in the
past not so much high magnitude earthquakes have affected the area in recent times. But in
the event that one occurs the region will be right in harm’s way.
Landslide is a hazard of regions with hilly terrains. In Sylhet the higher elevated
unconsolidated lands may pose a threat to those leaving on the foothills. The main reasons
behind landslide are-
Excessive rainfall
Unconsolidated sediment
Less vegetation
More steep sloping
Slopes usually dipping more than 30° are more susceptible to landslide. As Dupi Tila is
unconsolidated some parts of it are susceptible to landslides (figure 3.3).

Figure 3.3: Inhabitants on the foothills of Dupi Tila are susceptible to
landslides.
There are some environmental issues of the Sylhet trough that are worth mentioning. The
water and soil of the area is low in pH which indicates acidic characteristics. This is a hazard
considering crop production in the area is very much hindered because of it.
In the Sylhet trough, igneous and metamorphic rocks have been transported from the
Himalayas and Shillong Plateau by the rivers. The deposits are one of its major
environmental structures. In some places specifically in Dihing and Dupi Tila, it was seen
that the hills were cut by inhabitants for building materials and living purposes. It has a
harmful effect to the environment.
Stone Merchandising is a good business in the region. And so a large amount of stone
quarrying is done in the area, which is harmful to the air, soil, water in total the whole
environment. The gravel extraction sites like the one at Rangapani River (figure 3.4) can be
seen to be polluted and contributes to direct environment degradation.

Figure 3.4: Polluted stone quarry near Rangapani River.
Cutting hill & deforestation is another cause of hazard. Some people or industry cut the hills
then they use the mud for making houses or refill of low land.(Fig-3.5)
Figure-3.5 : Cutting hill and made up houses.

Figure 3.6- Hill cutting.
In the investigated area water is another problem. Mainly they use well for water. But the
dry season water level is lay down. So, they face some problem for production of crops &
domestic works

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, dam, barrage, and hazard especially 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
sources of any kind of hazard in the investigated area were studied.
Our guide teachers, course coordinator, Department and Dean Office tried to give us a best
effort to give a better field work. But there have some limitation thus are-
Our supplied base map is produced before 1990, so this base map isn’t place new GPS
position. So, that there make an error
As a new Department, our department doesn’t supply available tools and Equipment.
Ours staying place doesn’t stable. Their hotel isn’t available. So we stay Dakbanglo, School,
college etc. That place isn’t safe for us
• Budget for the field work isn’t proper.
• We haven’t proper time for study in that area.
• There have some transportation problem in the study area.
• Deforestation & hill cutting is create environmental problem.
• Stone query machine made some dump & also sound pollution.

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. For proper study time limit of study must be
increase. Deforestation & hill cutting must be stop. Give limitation for stone query.
I think our teachers done all things for us that we stay well and done better in our next field
work.

References
Alam, M., Alam, M.M., Curray, J.R., Chowdhury, A.L.R., Gani, M.R., 2003, An
overview of the sedimentary geology of the Bengal Basin in relation to the
regional tectonic framework and basin-fill history, Sedimentary Geology
Ashraf Uddin, Department of Geology and Geography, 210 Petrie Hall,
Auburn University, Auburn, AL 36849-5305, USA, Miocene sedimentation
and subsidence during continent–continent collision, Bengal basin,
Bangladesh.
Banglapedia.
Citrus Research Station, Jaintiapur, Sylhet
Encyclopedia Britanica.
Evans, P. (1933): Tertiary succession in Assam, than, geol. Inst. India, v-27.
Hari Prasad Paul’1988. Structure and tectonics of north Eastern part of the
Surma Basin,Sylhet,Bang.M.sc Thesis, Geology Dept. Dhaka university.
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.
Khan, 1980, Reimann, 1993, Uddin and Lundberg, 1999. Stratigraphic
succession of NE Bangladesh, Sylhet Trough
Mallet, 1876: Dinajpur shield named.
Mathur, L.p and Evans, P; 1964: Oil in India Inter.Geol. Cong. 22nd Session.
Md. Hussain monsur, An Introduction to The Quaternary Geology of
Bangladesh. A complimentary research of IGCP 347. Quaternary
Stratigrapgic Correlation of the Ganges-Brahmaputra Sediments (1995)
Uddin, M. J., Mohiuddin, A. S. M., Kamal, A. T. M. M. and Hossain, M. A.,
2012, The Agricultural Potentiality Of Some Wetland Soils Under Sylhet Basin
Of Bangladesh,

APPENDIX
▪ List of table
▪ List of figure
▪ Important figure

Appendix I
List of Tables
Table no Name of Table Page
1 Stratigraphic Succession of Sylhet Trough, Bangladesh 23
2 List of disaster in Bangladesh 45
List of Map
Map no Name of Map Page
1.1 Location Map of Jaintiapur, Sylhet 2
1.2 Upazila map of Jaintiapur, Sylhet. 3
1.3 Climate map of Bangladesh 10
1 Drainage patern of Investigated area 11
2.1 Satellite image which represents Regional topography and
stratigraphy of the investigated area.
24
3.1 Affected area of natural hazards in Bangladesh 46

List of Figures
Figure no Name of Figure Page
1.1 Hazard investigation by a local people 08
1.2 Sari River 12
1.3 Dauki River 13
1.4 Rangapani River 14
1.5 Noyagoan River 14
1.6 Tea garden in hill slope in Afifanagar. 15
1.7 Citrus Research Center plant. 16
1.8 Citrus Research Center plant. 17
2.1 Geo-tectonic provinces of the Bengal Basin. 20
2.2 Upliftment of Himalayas due to collision of Indian plate
and Eurasian plate.
21
2.3 3D simulation of the Bengal Basin 22
2.4 Fossiliferous Limestone 26
2.5 Contract Between Kopili Shale and highly gointed
Sylhet Lymestone
26
2.6 Fault breccias and Kopili shale created by Dauki
fault in Jaflong.
27
2.7 Outcrop of Kopili Shale 28
2.8 Outcrop of Kopili Shale 29
2.9 Topographic change due to Dauki fault. 30
2.10 collected Gypsum in kopili shale. 31
2.11 Outcrop of Barail Formation 33
2.12 Outcrop of Barail Formation 33
2.13 latrite bed in Barail Formation 34
2.14 Contact between Surma Group and Tipam
Sandstone found in Afifanagar
35
2.15 Parallel laminated Tipam sandstone beside Shari
River
36

Figure no Name of figure Page
2.16 Minor Fault in right bank of sari river, Tipam
Sandstone
37
2.17 Clay gall in Tipam Sandstone 38
2.18 Petrified trunk occurred in Tipam sandstone. 38
2.19 Contact between Girujan Clay (Left) and Dupi Tila
Sandstone (Right) found East bank of Shari River
39
2.20 Mottled Girujan Clay 40
2.21 outcrop of DupiTila sandstone 41
2.22 Cross bedding in right bank of sari river, Dupitila
Formation
41
2.23 Boulder bed of Dihing formation 42
2.24 Mud crack in Alluvium 43
3.1 Gravel withdrawing at Rangapani river 48
3.2 These areas are ravaged by flash floods during the
times of heavy rainfall. Picture was taken near
Gouri-Shankar village, close to Indian border.
50
3.3 Inhabitants on the foothills of Dupi Tila are susceptible to
landslides.
51
3.4 Polluted stone quarry near Rangapani River. 52
3.5 Cutting hill and made up houses. 53
3.6 Hill cutting 53

Appendix II
Location of the Stops and Attitude of beds
Day Stop Latitude (N) Longitude (E)
Attitude of Bed
Strike
Direction
Dip
Direction
Amount of
Dip
1 25°8’4.9’’ 92°7’45.5’’
1 25°5’46.4’’ 92°74.3’’ 268° SE 86°
2 25°5’49’’ 92°7’4’’
3 25°5’50.8’’ 92°8’39.3’’ 268° SE 40°
4 25°5’54.3’’ 92°8’40.4’’
5 25°6’37.3’’ 92°9’6.8’’
2 1 25°6’20.9’’ 92°10’32.2’’ 112° SW 70°
2 25°6’33.7’’ 92°10’42.1’’
3 25°6’20.5’’ 92°10’33.7’’
4 25°6’55’’ 92°10’55.7’’ 296° SW 54°
5 25°7’31’’ 92°11’14.8’’ 280° SW 34°
6 25°6’23.6’’ 92°8’57.2’’

3 1 25°8’5.3’’ 92°7’45.3’’ 274° SW 46°
2 25°8’20.6’’ 92°8’8’’
3 25°8’39.3’’ 92°7’47.6’’
4 25°8’55.9’’ 92°7’33.3’’ 280° SW 34°
5 25°8’24.4’’ 92°7’17.9’’ 255° SE 41°
6 25°10’37’’ 92°4’35.7’’ 236° NW 11°
7 25°10’54.9’’ 92°4’21.7’’
8 25°10’42.3’’ 92°4’29.5’’ 108° NW 6°
9 25°10’34.3’’ 92°3’44’’ 246° SE 21°
10 25°10’51.6’’ 92°1’59.9’’ 280° NW 12°
11 25°10’43.2’’ 92°1’38.9’’
4 1 25°10’34.9’’ 92°1’33.6’’ 288° SW 22°
2 25°10’43.4’’ 92°0’55.3’’ 272°,2800
SW,SE 36,22°
3 25°10’53.5’’ 92°1’55’’

EARTH SCIENCES FIELD WORK ALONG JAINTIAPUR - TAMABIL – JAFLONG SECTION; SYLHET, BANGLADESH.

EARTH SCIENCES FIELD WORK ALONG JAINTIAPUR - TAMABIL – JAFLONG SECTION; SYLHET, BANGLADESH.

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