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TIOMAN ISMP
CHAPTER 2B3 COASTAL GEOLOGY AND GEOMORPHOLOGY
2B3.1 Introduction
Pulau Tioman is the biggest island on the east coast of Peninsular Malaysia. It is a coral- fringed,
hilly island with a predominantly rocky and cliffed coast. There is a marked difference between
the coasts on the eastern and western sides of the island. Cliffed coasts, interrupted by small bays
where sands have accumulated to form pocket beaches, dominate the eastern coast. Juara is the
only bay of decent size here. In contrast, the western coast is mainly rocky with an apron of core
boulders and there are several bays of moderate size. The geology of Tioman, together with
coastline types and the distribution of fringing corals are shown in Figure 3-1.
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Figure 3-1. Geology and Coastline type of Tioman Island
2B3.2 Coastal Geology
.
The western portion of the island is composed mainly of granites and the eastern portion is
mainly acid-intermediate volcanics with lavas and tuffs of Permian (270-230 million years ago)
origin. In the process of intrusion by the plutonic rocks into the country volcanics, one of the
intrusion believed to have taken place about 75 million years ago (Upper Cretaceous), the contact
zones were metamorphosed. Minor intrusions are also very common in the vlolcanics along the
northern and southern coasts. In fact it is difficult to establish where the volcanics are replaced by
the plutonics along the southern coast. The geology map of Bean suggests the area about Tg. Duta
but observations on aerial photographs suggest a more westerly boundary. Faults are very
common along the east coast and a good example of a strike fault can be observed at Tg. Berhala
where the headland has been displaced laterally. The old fault scar remains well preserved.
Another faulted headland is Tg. Pisang Kera.
The coastal rocks and the geological structures of beddings, foldings, strikes, dips and faults play
a major influence on the character of the Tioman coast. The sites of geological interests where
exposures can be easily accessed are complied in Figure 3-2. Much of the information on the
geology of Tioman are compiled from the report by Khoo (1977) and Bean (1977), supplemented
by field observations and close scrutiny of the oblique aerial photographs. It is interesting to note
that some of the photographs illustrated in the report by Khoo could be picked up on the oblique
aerial photographs.
Quaternary sediments are limited on the island. Other than the marine deposits forming the
permatang plain of the major bays, there are only small areas of terrestrial deposits of gravel beds
and narrow alluvial tongues up river valleys. Small areas of swamp and paludal deposits occur in
lagoons and isolated areas of talus and scree slopes in front of cliffs. Some of the landslides have
formed boulder slopes along the coasts.
Tioman is underlain by volcanics of lava and pyroclastics, plutonics and contact metamorphic
rocks. According to Khoo (1977), its geological history appears to be similar to that of the eastern
region of the Malay Peninsula, with widespread volcanic and plutonic rocks and in contact areas
are metamorphic rocks. The overall geology of this Eastern Belt is distinctly different from the
rest of Peninsular Malaysia.
The coastal rocks of Tioman are described under volcanic rocks, plutonic rocks and metamorphic
rocks
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Figure 3-2. Sites of geological interests of Tioman Island
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2B3.2.1 Volcanic Rocks
The volcanic rocks consist of pyroclastics and lavas. These rocks are well exposed along cliffed
sections and some of their features can be observed on the oblique aerial photographs.
Pyroclastics
The pyroclastics include agglomerates and tuffacceous rocks. According to Khoo (1977), such
rocks can be observed at Tg. Keramat, along Teluk Bahai, at Teluk Juara near the mouth of
Sungai Bahru and at Tg. Puing. The rocks are usually acidic and contain rounded or angular
pyroclastics. The Juara agglomerates contain rounded fragments of grayish granitoids and black
tuffaceous rocks of pebble-boulder sizes and the matrix is of igneous origin. The presence of
granitoids in the agglomerates is an important discovery by Khoo (1977) who suggested that it
indicates that there are old granitoids which predated the volcanics. The volcanics were probably
built on a granitoid basement. Weathering of the agglomerates will release the pebbles and
boulders to form the gravel beach. This explains the widespread occurrence of gravel beach along
the east coast of Tioman.
The tuffaceous rocks in which lithic tuffs and welded tuffs (ignimbrites) are considered the most
attractive rocks on the island. These are widespread and can be observed at Tg. Keramat, Tg.
Mentawak, Tg. Beruntun and Tg. Tembuan. The tuffs of Beruntun are dark coloured and show
occasional cross bedding, suggesting a current direction from the northwest. Cross bedded tuffs
are also found at Keramat and Mentawak. The Beruntn tuffs also show bands of volcanic bombs.
At Teluk Bahai, the ignimbrites show graded bedding, with the fragments at the bottom about
1cm and those on top about 0.1cm.
Lavas
Lava flows are inter-bedded with the pyroclastics and are found in areas of volcanics. Khoo
(1977) recognized several varieties. For example, the Tembuan-Ruit lavas are greenish-grey
porphyritic hornblende-biotite dacite with plagioclase phenocrysts and dark green non-porphyritic
hornblende-biotite-quartz andesite. Others include non-porphyritic pale greenish rhyolite and dark
grey porphyritic hornblende dacite.
2B3.2.2 Plutonic Rocks
Plutonic rocks are the dominant rocks in Tioman and occur mainly on the western half of the
island and form the headlands that separate bays. Small bodies outcrop along the coast elsewhere
as intrusions. The various types of plutonic rocks on Tioman include granitoids, the most
dominant group and intermediate rocks such as quartz diorites and quartz monzonites. Basic
plutonic rocks such as dolerites are rare.
Granitoids
The granitoids form a small batholithic mass that forms most of the southern parts of the island.
The main type is a pink spotted non-porphyritic adamellite, that forms Tg. Said, Tg. Berhala
(Berjaya) and at Genting. Blocks and boulders of adamellite bordering the sea are
characteristically rounded, the result of spheroidal weathering and derived from core stones. For
example, at Tg. Berhala, both rooted outcrops and free boulders of adamellite exhibit spheroidal
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weathering. The adamellite occasionally contains dark biotite-rich inclusions which may be
xenoliths, such as those of Tg. Berhala. . The granitoids are occasionally veined by quartz and
fine-medium grained acid intrusive rocks. Volcanic rocks adjacent to the granitoids may be
permeated and intruded by granitoids as dykes, veins and small masses. Examples of these
include the cliffed sections along the northern coast, along Tanjung Ruit- Tg. Tembuan headland,
at Tg. Beruntun and Tg. Mentawak along the eastern coast and near Tg. Duata on the southern
coast.
Diorites and Monzonites
These occur in the northwestern and east-central part of Tioman but do not outcrop along the
coast.
Basic Rocks
Gabbroic rocks outcrop at the headlands bordering Teluk Dungun and occur as doleritic sheets
from the Tembuan-Ruit headland to Tg. Saing. The doleritic sheets appear to be the youngest
crystalline rocks on the island and also cut granitoids which intrude the volcanic rocks (Khoo
1977). At Tg. Tembuan, a 1.5m thick, grey-green, medium grained non porphyritic dolerite dyke
cuts xenolithic granite and tuffaceous rocks.
2B3.2.3 Metamorphic Rocks
Metamorphic rocks are much less abundant compared to the other two groups. They are mainly
contact metamorphosed volcanic rocks and occur in Salang, Asah, Tg. Mentawak and Tg
Tembuan-Tg. Ruit headland. Three types of metamorphosed vocanics can be recognized. These
are metamorphosed acid volcanics, metamorphosed calcic volcanics and metamorphosed
tuffaceous volcanics.
The acid volcanics when metamorphosed have fine grained feldspathic ground masses. At Salang,
fine sillimanite needles form veinlets in hornfelsic quartzo-fedspathic metamorphosed volcanics.
Bean (1977) reported the occurrence of hornfels at Tg. Mentawak.
Calcic volcanics when metamorphosed develop hornblende and epidote which give the rock a
greenish colour. These are generally coarser grained than the metamorphosed acid volcanics.
Metamorphosed ignimbrites (tuffaceous volcanics) at Tg. Tembuan, Asah and Tg. Atas
developed small red garnets.
2B3.3.4 Faults
The most prominent fault observed along the coast is undoubtedly the strike fault at Tg. Berhala
(south-east coast) in which the headland has been laterally displaced southwards exposing the
face of the fault scarp behind it. There appears to be some downward displacement too. Other
faults include the faulted headland of Pisang Kera and Bahai. The faults have resulted in the
formation of plunging cliffs or fault scarps overlooking the coast. The fault lines also locally
influence the alignment of the coastlines. It cannot be determined at this stage whether the faults
running across the headlands are part of the same fault or belong to different fault lines. Besides
the major faults, smaller ones are common and often lie close to one another. The faults are not as
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extensive as those observed on Pulau Sembilang and Pulau Seri Buat, where the faults can be
traced on portion of the island to another.
2B3.3 Coastal Geomorphology
Around the coast is widespread evidence of former high sea levels in the form of a raised coral
reef at Gerrengan and at Kampung Juara. During the development of the resort at Kampung
Lalang, buried coral heads were excavated from below the sand plain. A coral sample lying 2.7m
above the April high tide level at Juara was radiocarbon-dated at about 6,000 years (Khoo 1977).
Beach rocks composed of mainly coral fragments, shells, sands and gravels, usually cemented by
carbonates but occasionally by iron oxides derived from weathering of iron bearing minerals in
the adamellite, are common. These features lying up to 2m above mean sea level are preserved in
crevices or exposed along the coast. There are also dead coral reefs, one showing a spiral form
exposed during low tide near Kampung Tekek. At Kampung Tekek the littoral drift is
southwestwards and the river mouth is deflected towards Kampung Lalang. The river delivers
reddish sands to the coast, the sediments generated by construction inland, including that of an
airstrip. There was a period of severe erosion at Tekek in the 1980s, which resulted in the
construction of a massive sea wall to protect the village. The rocks were sourced from the
mainland in Terengganu. In front of the Tanjung Said rocky headland is a dead coral reef
exposed during low tide and exposures of beach rock. At Kampung Lalang, the location of
Berjaya Tioman Beach Resort, littoral drift is northeastwards and a protrusion with a small spit at
the mouth of Sungai Lalang has been deflected in the direction of net littoral drift. The white
sandy beach has experienced mild erosion and a scarp has formed behind the beach. Off shore are
fringing reefs with a shallow lagoon shoreward of it. The lagoon area in front of Sungai Lalang is
filling up by sediments generated by the cutting of hills for the construction of a golf course.
Sands taken from the beach for the sand bunkers may be a contributing reason for the beach
erosion. The coast from Tanjung Permata to Tanjung Lanting is rocky, with a series of deep
indented pocket beaches along the western portion and a broader bay at Gerenggan and Mukut.
The coast becomes rocky again eastwards with small patches of sandy beach. This stretch of
coastline has the most spectacular landscape dominated by the twin peak of Batu Sirau and Nenek
Si Mukut.
Surprisingly there is very little sand movement by wind action and dunes are absent. Some sand
movement was observed in Juara-Mentawak and a few other beaches but these were very minor
and have not resulted even in the development of embryo dunes. The dune building vegetation
Spinifex littoreus was not observed anywhere on the island and its absence may be the result of
little aeolian sands or the absence of dunes may be the result of it.
2B3.4 Coastline Types
The coastline types of Tioman are shown in Figure 2B3.1. The different types are mapped based
on aerial photo interpretation of oblique aerial photographs and from field surveys. Actual
measurements were carried out for beaches and the man-made coast, and the rest can be regarded
as cliffed and rocky coasts as true cliffs form a very small of the coasts. Mangrove coast can be
regarded as absent. To avoid double counting of man-made coast and beaches as the man-made
coast is front by a beach during mid tide, the category is described as man-made coast with
beaches. The different coastline types are summarized in Table 3-1.
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Table 3-1. Coastline types of Tioman
Type of Coast
Beaches
Length ( km)
18.71
Per cent
27.3
Man-made coast with 0.75
beach in front
Mangroves
0
Cliffs
See below
1.1
Cliffed coast and 49.04
rocky-boulder coast
Total
68.5
71.6
100.0
Comment
Underestimate, short stretches not
included
Described this way to avoid double
counting
Neglibible
Grades into cliffed coast and this
category presents a problem, included
under cliffed coast type
An overestimate as included pocket
beaches
Length as given in NCES 1985
As expected, the broad category of cliffs, cliffed coasts and rocky-boulder coasts dominate the the
68.5 km long Tioman coastline, constituting 71.6 per cent. The length of major beaches is 18.71
km long and forms 29.3 percent. The rest are man-made coasts with beaches. If beaches and manmade coasts with beaches are combined then beaches would constitute 28.4 per cent of Tioman’s
coastline. The length of beaches is an underestimate as short sandy stretches and pocket beaches
of the east coast are not included. It is useful to know the length of beaches as its length has been
used in estimating the carrying capacity of beaches. A loss of beaches would make the island less
attractive and decrease its carrying capacity.
2B3.4.1 Beaches
The beaches occur intermittently around the island. Most are concentrated along the western and
southern coast but Juara and Mentawk on the east coast have the longest stretch of sandy beaches
in Tioman. The slightly arcuate line of beach in Juara is 1105.5m long without any interruptions
whereas the slightly longer beach of Juara at 1300m long has interrupted about mid-bay by rocky
outcrops. The longest bay is Tekek but the beaches there are not continuous, broken up by
seawalls, and gravelly and small headlands in towards the north. In fact most of the bays along
the west coast of Tioman are lined by sandy and gravelly beaches, the latter usually more
prominent towards the northern end, as in Air Batang, Tekek and Genting. Along the southern
coasts, the beaches are usually of short stretches in front of coastal slopes and estuaries, without
any development of a backing permatang plain as happen along the west and east coast. Beaches
are generally absent along the north coast. Along the east coast, sandy and gravelly beaches have
formed along the heads of most bays. There are also pocket beaches usually of coralline sands
nested within small indentations. Landslides have modified some of the beaches, either by
burying them or fragmenting a former continuous beach into discrete compartments. The beaches
are usually aligned normal to the direction of wave approach. A few of the beaches are associated
with spits but most are ‘mainland’ beaches. The sands for beach formation are derived from
various sources, the finer sediments from offshore and fluvial sources and the gravels from fast
flowing streams, eroding gravel terraces and from land slides.
2B3.4.2 Cliffed and Rocky Coasts
Cliffed and rocky coasts form the majority of the coastline in Pulau Tioman. These are generally
referred to as simply ‘rocky’ coast. The terminology used to describe various types of ‘rocky’
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coasts is explained in Chapter 4 on the evolution of such coasts. Nearly the whole length of the
north coast is ‘rocky’ and also on the east coast, other than Juara-Mentawak. The whole spectrum
of ‘rocky’ coasts from boulder coast to plunging cliffs is found on the island. Boulder coasts
dominate the ‘rocky’ coast on the eastern side of the island and this type normally develops on
granite outcrops, where rounded core stones washed out from the retreating slopes have
accumulate along the water’s edge to form an apron of boulders. A good example of a boulder
coast is Tumuk Island and Tg. Pauh. In the volcanic rocks of the east coast the country rocks are
exposed to form a short wall element without an apron of protective rocks and these are generally
referred to as rocky coasts. As the wall element becomes progressively higher with further retreat
of the coastline, the rocky coast evolves to become a cliffed coast (slope over wall) and finally
ends up as a cliff, where the wall element dominates the slope element above. Most of the socalled cliffs on Tioman are actually cliffed coasts and have not achieved the status of cliffs.
2B3.4.3 Cliffs
Cliffs are rare and where they occur is usually associated with faulted headlands. Isolated cliffs of
short distances occur in Tg. Atas, Tg. Peradung, Tg. Temdur, Tg Bahai and Tg. Berhala.
Semblance of cliffs are found in Tg Chekau, the headland south of Teluk Naut and at Tg. Mak
Nari just west of Asah. Some of the cliffs plunge into deep waters. In general active cliffing
appears to have stopped and the wall element is becoming degraded and colonized by grasses and
small bushes.
2B3.4.4 Mangroves
Ocean front mangroves are rare on the island and those in Air Batang and Mukut are remnants of
a former more extensive stand. Along the east coast, small stands have established themselves on
gravel lobes where some clay materials from slides provide a foothold for them. Small areas of
mangroves are found in Nipah lagoon and along the tidal reaches, for example that of Sg.
Genting.
2B3.4.5 Man – made Coast
The 750m long felxislab interlocking wall of Tekek emplaced around 1993 in front of Tekek spit
represents the only extensive form of man-made coast. Behind the wall is an esplanade and
eating shops and the road behind the wall, meant for pedestrians, is used by locals as a normal
road. The beach in front of the all has depleted. The wall toe is exposed in places and the slabs are
beginning to collapse. There are plans to revet or re-nourish the whole bay and the outer edge of
the nourished beach will be protected with geotubes. This implementation will see an increase in
the proportion of man-made coast on Tioman Island.
2B3.5 Coastal Geomorphology of Selected Coasts
The beach morphology of selected coasts mapped using DGPS is illustrated below with a short
description. The examples are taken from the east coast (Juara), south coast (Mentawak) and west
coast (Genting, Paya). Most beaches do not have a backing berm and are fronted by a broad dead
coral reef with a veneer of gravels.
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2B3.5.1 Juara Bay
The coastal geomorphology of Juara Bay is shown in Figure 3-3. It consists of a broad permatang
plain fronted by sandy beaches. The dead coral terrace that forms the inter-tidal area so dominant
along the southern and western bays are absent except for a small exposure near Tg. Beruntun.
The beaches are broader compared to the rest of Tioman beaches and a small spit extends across
the river mouth at the northern end. The permatang plain is composed of a series of beach ridges
trending parallel to the present coastline and below the sands are dead corals, some of which are
exposed along river banks. There is little sand movement and dunes are absent. Juara is the most
exposed of all bays in Tioman and the beach is reflective and swash aligned. No shoreward
migrating swash bars were observed nut the berms were fairly wide in places. The beaches appear
to be highly dynamic showing significant changes during the two visits to the bay.
Figure 3-3. Coastal geomorphology of Juara
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2B3.5.2 Mukut Bay
The beach morphology of Mukut Bay is shown in Figure 3-4. In contrast to the sandy bay of
Juara, there are little sediments of sand size. Instead, the beaches are usually composed of coral
fragments and gravels of various sizes. An exception is Pasir Kelupak in west Mukut. In front of
the Mukut beach is a wide expanse of dead coral reefs, the surface strewn with gravels and
boulders, showing some degree of sorting. Silty–muddy patches occur locally. The reefs help to
protect the beach from wave attack and the severe erosion here would have been worse if not for
the reefs. Several channels are dredged across the reefs to provide access for small boats. The
coastal scarp is prominent and runs along the whole bay. The permatang plain, where present, is
very narrow, composed of a few ridges. On eroding beach faces, accumulations of heavy minerals
are often observed.
Figure 3-4. Coastal geomorphology of Mukut West
Some of the coastal morphology of Mukut bay is illustrated in Figure 3-5. The main character of
Mukut would be the gravel lobes. The gravels and boulders are very well rounded and are
probably the end product of more than one cycle of erosion. The gravels are rather thick in places
and form a complete cover over the dead reef, which are seldom exposed.
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Beach with fronting gravels
Tg. Kelupak headland
Kelupak beach and stranded corals
Gravel lobe near jetty
Figure 3-5. Coastal morphology of West Mukut
2B3.5.3 Genting Bay
The coastal geomorphology of Genting north is shown in Figure 3-6. In front of a narrow
permatang plain dotted with fluted tors is a narrow beach and a broad terrace of stranded corals
with wide patches of sands. Along the outer edge of the dead reefs, there is coral revival and
excellent growth locally. The reef helps to dissipate the energy of incoming waves and protect the
narrow beaches from severe erosion. The reef is being lowered by abrasion but more resistant
coral heads stand slightly higher. Aeolian activity is minimal and dunes are absent. The coastal
land here is low-lying and highly vulnerable to wave overwash.
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Figure 3-6. Coastal geomorphology of Genting North
Some of the characteristics of Genting north are illustrated in Figure 3-7.
Fluted tors in the backing hill and narrow
permatang plain
Reef regeneration
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Narrow beach and fringing gravels
Dissection and lowering of stranded coral
terrace
Figure 3-7. Character of the Genting north coast
2B3.5.4 Paya Bay
The coastal geomorphology of Paya Bay is shown in Figure 3-8. In front of the backing hill is a
permatang plain in which a few ridges can be recognized. Most of the ridges have been leveled to
make way for a big resort. Patches of heath vegetation associated with beach ridges remain. As
Sg. Paya approaches the coast, it is deflected northwards by an elongating spit and finally drains
into the northern end of the bay near Pulau Tumuk. The spit appears to be actively elongating
judging from the pioneer vegetation on the spit and the few kampong houses with the appearance
of a squatter settlement. The distal end of the spit has yet to be alienated based on the information
on the cadastral map for the area. In front of the river mouth is a small delta, built up of fluvial
sands. Offshore are sands bars which extend to Pulau Tumuk. The beach is drift aligned and
dissipative, with a wide inter-tidal terrace of dead corals attenuating incoming wave energy. An
apron of tightly packed boulders lines the headlands and Pulau Tumuk. On the northern side of
Tumuk, the oysters form a ring around the boulders to give a mushroom-like appearance. On the
southern portion of the bay the beach is more reflective as the sea in front has no protective coral
dead reef and the sea bottom is deep and sandy. The beach here is also wider.
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Figure 3-8. Coastal geomorphology of Paya Bay
Relic oysters are commonly found among crevices in the southern headland where the bluish–
black plutonic rocks show various forms of weathering. Just off the southern headland and in
front of the beach near the jetty are living corals. Some of the characteristics of Paya Bay are
shown in Figure 3-9.
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Sandy beach with deep water and sandy Stranded coral reef
bottom in front
Paya spit
Paya permatang
Figure 3-9. Coastal geomorphology of Paya Bay
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