The way our planet formed gives us evidence for past events and life on earth and can help us make important decisions for the future. Geology, the study of earth, examines materials that constitute our world and the processes that have changed them. This topic helps you to explore geological time and the appearance of humans. Plate tectonics are introduced as important drivers of global patterns. Sea level and ice-volume changes and cycles are presented and effects linked to change in climate and vegetation. Catastrophic extra-terrestrial activity is discussed. Malaysia’s formation, including mountain ranges and caves, is outlined. To complete this topic explore all concepts within each theme and examine and understand the resources and references identified below.
The Earth’s formation over geological time has shaped the resource bases of all countries, determining spatial location and environmental conditions including the very composition of the ground.
The Earth’s formation over geological time has shaped the resource bases of all countries, determining the spatial location and environmental conditions including the composition of rocks and minerals. The Earth was formed around 4.6 billion years ago, and for the first 4 billion years or so (the Precambrian) life evolved and the composition of Earth’s atmosphere was drastically modified. There are few fossil remains from the Precambrian period and by comparison much more detail is known about subsequent changes in the eras that followed (see Figure 2.2). These temporal classes have emerged very recently (20th century) as geologic science has moved from relative dating of sedimentary rock layers to radiometric dating of material.
The Paleozoic era (541-252 million years ago or Ma) is when living organisms evolved from marine-dwellers to life on land, with the development of amphibians, insects and reptiles. Land plants evolved from simple moss-like forms to ancient trees like Lepidodendron which had lignin and a vascular system, but no leaves or flowers. This era consists of six periods: the Cambrian (541-485 Ma), Ordovician (485-444Ma), Silurian (444-420 Ma), Devonian (419-359 Ma), Carboniferous (359-299 Ma) and Permian (299-252 Ma). 25% of Peninsular Malaysia is covered by outcrops of Paleozoic rocks.
The Mesozoic era (252-66 million years ago) is best known as the era when dinosaurs came to dominate Earth’s land masses and comprises three periods: the Triassic (252-201 Ma), Jurassic (201-145 Ma) and Cretaceous (145-65.5 Ma). During this time, intense tectonic activity was important as the continent of Pangaea was formed and flowering plants were recorded in the fossil record from the Cretaceous period. The era ended abruptly with the extinction of the dinosaurs.
The Cenozoic (65.5 Ma- present) era comprises three periods: Paleogene (65.5-23 Ma), Neogene (23-2.588 Ma), and Quaternary (2.588 Ma- present). The extinction of the dinosaurs provided the opportunity for mammals to flourish during this era. The temperature trends during this era are towards a drying and cooling trend, ending in the final period of Quaternary glaciations. Humans evolved during the Quaternary period; about 2 million years ago (2,000,000) hominids were sharpening rocks to use as tools and about twenty five thousand years ago (25,000) Homo sapiens began to spread throughout the globe.
Much of the geological history of the earth is expressed as movement of geological plates across the molten interior of the earth. The motion of the earth’s lithosphere is described by the field known as plate tectonics. (Figure 1.3). Movements Earth’s plates has led to different configurations and positions of the continents over the past 600million years.
Figure 2.3 Geological Plates. Public Domain.
Where the edges of these plates meet one another (Figure 2.4) enormous power is generated resulting sometimes in large scale events such as volcanic eruptions, earthquakes and associated phenomena such as tsunamis and climate disruption. The Pacific Ring of Fire is a subduction zone; an area around which oceanic plate often descends beneath continental plate causing dramatic seismic activity that is sometimes observed at the surface.
A geographical position within the Pacific Ring of Fire helps to explain why locations such as Japan, Philippines and San Francisco in the US as well as Western South America are so prone to geological disturbance (identify their positions in Figure 2.5) 90% of earthquakes occur in this region of high seismic activity (National Geographic, 2015).
Despite Malaysia’s positioning relative to the Ring of Fire, Malaysia has only one potentially active volcano (see Figure 2.6) Bombalai, situated in North East Borneo (Tahir et al, 2010).
Tropical East Asia is composed of a number of continental fragments which have come together over the last 400 million years from the southern supercontinent known as Gondwanaland which existed during the Paleozoic (541-252 Ma) and early Mesozoic eras, and started to break up in the early Jurassic (184 Ma). Gondwanaland included the fragments of Malaysia and most of today’s Southern hemisphere landmasses with the Arabian Peninsula and Indian subcontinent. At this time the land fragments of Malaysia were widely scattered and for much of the Paleozoic era some of the land masses were submerged by the Paleo-Tethys Ocean. The eastern parts of Peninsula Malaysia were located at the equator under shallow seas. The land fragments which today make up parts of China (Si- Sino), Burma (bu), the western Malay Peninsula and part of Thailand (ma) and Sumatra (Su) were part of a conjoined land mass called Sibumasu. The exposed mass of Sibumasu was located next to Australia at 40 ºS during the Carboniferous period (359-299 Ma) and surrounded by shallow seas. Rocks from Langkawi deposited at this time indicate glacial conditions on Gondwanaland and a cool water flora (the Singa formation of pebbly mudstones and diamictites; Figure XX). During the Permian period (299-252 Ma) of the Late Paleozoic, Sibumasu broke away from Gondwanaland and started to migrate northwards to reach northern equatorial latitudes by the end of the era. For much of the Paleozoic era some of the land masses that would go on to make up Malaysia were submerged by The Paleotethys Ocean, resulting in the deposition of materials that would eventually make sedimentary rocks from the marine (carbonate materials that make up limestone) or fluvial (from rivers on land discharging into the sea to form sandstones and mudstones) deposits. By the late Paleozoic the Paleo-Tethys Ocean was starting to close as continents collided to form one supercontinent of Pangaea.
Figure 2.8 shows how scientists have pieced together the geological puzzle of continental drift through, for example, fossil identification. Figure 2.7 shows mudstone and dropstone pebbles from the Singa formation on Langkawi Island deposited 350-290Ma (Carboniferous Period), indicating that glacial deposition into the sea which became incorporated into this sedimentary rock.
The early Mesozoic (during the Traissic period 252-201 Ma) was a time of intense tectonic movement as Pangaea was formed. This led to extensive magmatic intrusion as sedimentary rocks were transformed into metamorphic rocks forming mountains (the process of orogeny). Sibumisu, East Malaya and Indochina collided in an event known as the Indosinian orogeny, which closed the Paleo-Tethys Ocean in the early Mesozoic Era around 200Ma. This convergence resulted in the formation of a feature known as the Bentong-Raub suture; an arc-shaped folding belt which stretches along the length of the Malay Peninsular into Thailand and Yunnan forming the Titiwangsa mountain range. As the Paleo-Tethys Ocean subducted under East Malaya-IndoChina, Permo-Triassic volcanic activity created I-type granites. Comparisons of rock strata from the west and east of Peninsular Malaysia confirms that they derive from different sources, with the east of the Peninsular containing more andesitic rocks derived from volcanism and associated with subduction which are absent in the west. As the land masses squeezed together there was faulting which cut obliquely to the collision zone and exposed older S-type granites which are formed through metamorphosis of sedimentary rocks. These granites are highly significant to Malaysia’s history because they bear tin. By the end of the Mesozoic era Gondwanaland began to break up, pushing Africa and India north and opening up the Indian Ocean. The era ended with the mass extinction of the dinosaurs 65.5 million years ago.
The continental land masses were very dynamic during the Cenozoic era (65.5 Ma to present), andeventually became configured in today’s familiar form. The Indian continental fragment migrated north at a rapid pace of around 21cm per year and merged with the Eurasian plate around 50 million years ago (Figure 2.9).
Through a process of subduction (see Figure 2.10) the ocean basins between continental fragments and Gondwana were successively destroyed leading to the merging of continental fragments. India’s main collision with Eurasia, in Tibet, probably occurred around 55 million years ago, having impact on the shape, climate and biogeography of the East Asia region (Norton, 1979).
This collision had a major impact on the shape, climate and biogeography of the East Asia region (Norton, 1979), leading to the formation of the Himalayas in a more widespread event called the Alpide orogeny and associated with the opening of the Sunda trench. Around 25 million years ago, the Philippine and Asian plates collided with Australia. This continuing collision has produced much of the tectonic and volcanic activity in this region. The formation of Borneo was relatively recent. Between the Oligocene (34-23Ma) part of E Sabah drifted southwards to join the rest of the Borneo land mass in the Miocene (23-5Ma). The Sabah land area grew by capturing the eastern Sabah microcontinent and by accretion associated with subduction of the S China basal crust. The suture of East and West Borneo during this era has resulted in very active crustal processes including earthquakes, volcanism and diapirism (“mud volcanoes”) in Borneo as the South China basal crust subducts. This elevated created the conditions for fluvial erosion and deposition, resulting in the deposition of clays and shales (The Miri formation) 10-15 million years ago in a shallow deltaic environment. By 10 million years ago Southeast Asia had progressed to approximately its present position (Patriart, 1984 and see Figure 1.11).
By the end of the Cretaceous period 65 million years ago, the basic shape of Tropical East Asia had emerged.
Around 25 million years ago, the Australian and Indian plates having now joined, the Philippine and Asian plates collided with Australia. This continuing collision has produced much of the tectonic and volcanic activity in this region. By 10 million years ago Southeast Asia had progressed to approximately its present topographical form (Patriart, 1984 and see Figure 2.12).
Sea level change has been the principal factor determining land connections and land area in Tropical East Asia over the Cenozoic era (65.5Ma- present). Ice sheet formation in Polar Regions is a major driver of sea level change, as a greater proportion of the Earth’s water budget falls as snow and becomes trapped as glacial ice for millions of years, leading to lowering of sea levels. Cenozoic sea levels may have been several hundred metres higher 55 million years ago during the warm Paleocene-Eocene thermal maximum. Subsequently, a long-term cooling trend led first to Antarctic glaciation 35 million years ago and then to the slow descent into the Quaternary glaciation which began 2.588 million years ago and resulted in the creation of Northern Hemisphere ice sheets. Quaternary variability in ice sheet volume is driven primarily by orbital variations, resulting in sea level lowering of more than 100m in the cold glacial periods relative to the warmer interglacials. During the Last Glacial Maximum (around 21,000 years ago) the shallow seas in the region were exposed, linking Peninsula Malaysia, Borneo, Sumatra and Java into one land mass called Sundaland. River networks on the land were extended into the exposed sea beds using trenches for channels to form the Sunda River, which linked Sarawak and Peninsula Malaysia with the broader Mekong drainage network. These high-stands and low-stands are key to understanding current plant and animal distributions. By about 10, 000 years ago, as the ice sheets receded sea levels increased and severed terrestrial connectivity between most major islands. In the past decades sea level rise shows a degree of acceleration not previously observed in the Earth’s history (Church and White, 2006).
Across all time-scales the climate of the earth is changing. Atmospheric composition has been an important driver of climate over geological timescales, with higher concentrations of the greenhouse gas carbon dioxide usually associated with warmer periods. The atmosphere throughout most of the Paleozoic era was rich in carbon dioxide, which caused very acidic rain, leading to active chemical weathering. Warm temperatures existed for much of this era, apart from some short-lived ice ages straddling the Ordovician and Silurian periods (the Early Paleozoic Icehouse) and in the late Carboniferous Ice Age. The position and size of continental land masses also exerted considerable influence on terrestrial climate. For example, southerly location of Gondwanaland s during the early Paleozoic meant that the land masses were exposed to cooler temperatures than the global average. The size of land masses was also important because of the “continental effect” which restricts the amount of precipitation which can reach inland areas and accentuates seasonal temperature differences. During the Triassic and Jurassic periods of the Mesozoic era, conditions were extremely hot and dry with extensive inland deserts because of the vast size of the super-continent Pangaea, excellently suited to the reptilian dinosaurs. These conditions started to change as Pangaea started to break up during the Cretaceous Period.
Over the past 50 million years a global cooling trend has culminated in the presence of massive Northern-Hemisphere ice sheets from 2.588 million years ago; the start of the Quaternary period. Within this period, global ice volume has changed, initially on a 41,000 year (reflecting axial tilt) and then a 100,000 year cycle (reflecting orbital eccentricity) of glacial (cold) and interglacial (warm) periods, driven by the Earth’s orbital positon relative to the sun. The effects of these fluctuations in ice volume are not confined to the polar latitudes, but are global in extent. Northern Hemisphere ice sheets in the North Atlantic region affects ocean circulation (thermohaline circulation) and therefore global heat transport. Ice sheet growth also lowers sea levels and, because of their great height they can disrupt atmospheric circulation. Each of these factors can strongly influence climate in lower latitudes and tropical regions. At glacial maxima (Figure 1.15), large areas of shallow and warm sea are replaced by cool dry land in this region, resulting in a decline in rainfall and strengthening and weakening of winter and summer monsoons respectively. For example, pollen records from the Niah Great Cave in Sarawak indicate an increase in fire tolerant plant species and an expansion of coastal swamp around 50,000 years ago as the glacial period intensified and sea levels lowered. The lower temperatures associated with glacial periods can lead to localized formation of ice caps in montane regions where temperatures are cooler. During the coldest period of the last glacial (the Last Glacial Maximum; 21,000 years ago) a 5.5 km2 ice cap formed on the region around Mount Kinabalu in Sabah, leaving behind classical evidence of ice activity such as cirques, U-valleys and roche moutonnes.
Superimposed on the changes driven by glaciation, monsoon intensity also changes in the tropics on a 23,000 year cycle (driven by orbital precession). This cycle influences the summer monsoon in East Asia by changing the amount of solar radiation energy that reaches the Northern Hemisphere during the summer. Because monsoons are caused by temperature differences between land and sea, changes in solar radiation can influence the strength of monsoons.
Recently, global temperatures have warmed at an unprecedented rate, especially in the last 60 years, providing unprecedented and clear scientific evidence for warming caused by anthropogenic emissions of greenhouse gases. (Intergovernmental Panel on Climate Change and see Figure 2.17 and Figure 2.17).
65 million years ago a massive asteroid travelling at approximately 20km per second and with a diameter of around 10 km hit what is now the Yucatan peninsula in Mexico near the village of Chicxulub. It left a crater (see Figure 2.18 and the Chicxulub impact crater) more than 150km wide and would have destroyed everything within a 900km radius. Outside this impact zone, giant tsunamis several hundred metres high were generated for weeks following the impact. The rocks that were hit by the asteroid contained sulphur and toxic dust was spread throughout the world. Meanwhile in India a series of volcanic eruptions were triggered- it is not known whether the two events are linked. However, the combination of toxic water and air, and tsunami inundation of the land led to the most notorious mass extinction event in history: the Cretaceous-Paleogene (K-Pg) event which eliminated three quarters of all plant and animal species on earth and led to the global extinction of the dinosaurs. Although the K-Pg mass extinction is very well known, several mass extinction events preceded this with the most devastating probably being the Permian-Triassic mass extinction (P-Tr) (252 Ma). This was associated with the formation of Pangaea which led to increasingly harsh and arid conditions on land and precipitated mass volcanism as continental plates collided, destabilizing the climate system and eliminating 90% of species on land.
In Malaysia it is estimated that there may be 15 circular features which derive from extra-terrestrial impacts. One of the best studied is the Mahsuri Ring on Langkawi Island, thought to have been created 10 million years ago and still visible from the top of Mount Raya. Whilst this events undoubtedly caused wide-scale destruction and change, it was of a much smaller magnitude than the Chicxulub impact
This extra-terrestrial event precipitated the global extinction of the dinosaurs and many other terrestrial vertebrate species. A more recent impact of an object likely over a Kilometre in diameter struck South East Asia at a low-angle around 800,000 years ago, though its impact crater has yet to be found and is likely under marine sediment. Whilst these events cause undoubted wide-scale destruction and change, it takes an exceptional event such as the Chicxulub impact to have a major lasting effect on biodiversity, even this enormous impact produced less severe extinctions in plant species than animal species.
Where the edges of continental plates meet one another enormous power is generated resulting sometimes in large scale events such as volcanic eruptions, earthquakes and associated phenomena such as tsunamis and climate disruption. This process is evident at the Pacific Ring of Fire- a subduction zone where oceanic plate descends beneath continental plate causing dramatic seismic activity that is sometimes observed at the surface. The Pacific Ring of Fire helps to explain why locations such as Japan, Philippines and San Francisco in the US as well as western South America are so prone to geological disturbance (identify their positions in Figure 1.5) 90% of earthquakes occur in this region of high seismic activity (National Geographic, 2015). Malaysia is positioned away from this active subduction zone and so has only one potentially active volcano (see Figure 1.6) Bombalai, situated in North East Borneo (Tahir et al, 2010). The processes at the ring of fire help to understand how some of the Southeast Asian rocks were formed.
After the Pacific Ring of Fire, the most seismically active region is the Alpide belt which was created by the collision of the African, Arabian and Indian plates with Eurasia. The belt extends along Southern Europe and Eurasia, including the Cantabrian Mountains, Pyrenees, Alps, Sudetes, Carpathians, Balkans, and Crimean Mountains (See Figure 1.19 excluding ranges in parenthesis named for reference only). It includes the Caucasus Mountains, mountains of Anatolia and Iran, the Hindu Kush, and the Himalayas. Energy released in earthquakes from the Alpide Belt is only around 15% of the world total (Britannica, 2015). The belt extends into Southeast Asia including the Malay Peninsula, Java and Sumatra.
The Sunda volcanic arc is an excellent example of a volcanic island arc (common in the Southeast Asian region) spanning from North-West Sumatra to the Banda Sea and caused by subduction of the Indian Ocean crust beneath the Asian tectonic plate. Associated with this feature, the Sumatra-Andaman earthquake on 26th December 2004 produced a tsunami which killed upwards of 200,000 people. Indeed, volcanic events are especially common in South-East Asia due to the complex underlying tectonics of the area.
In human history the largest eruption, heard 2600km away in Borneo was the Tambora volcano which killed over 50,000 people in 1815 and led to widespread cooling as recorded in the Northern Hemisphere. Other large eruptions have been those of Krakatau in 1883, Agung in 1963 and Pinatubo, in the Philippines, in 1991 (see Figure which shows bubble size according to tephra ejected, convergent boundaries in pink, divergent in blue, dashed annulus approximates equivalent ejection from the Chicxulub impact). Megathrust sites,sites where one tectonic plate subducts beneath another, can also cause localized or regional destruction
The Malay Peninsula, subject to the global sea and climate changes of the Quaternary period, has been influenced by depositional processes, especially in coastal areas. Hutchison and Tan (2009) divide the peninsula into denudational or depositional terrains: the former being areas greater than 15 metres above sea level and the latter those areas below. The Cenozoic geological history that defines Peninsula Malaysia began with shallow water continental margin sediments “deposited directly on the eroded surface of the pre-Tertiary Sundaland basement: erosion extending from the last Cretaceous in to the early Tertiary” (Hutchison and Tan, 2009, p5).
The processes described in this topic have formed the landscapes and geology of Peninsular Malaysia and Borneo. For some of the early Cenozoic, when sea levels were higher much of the land masses would have been covered by shallow seas depositing sediments onto the previously-deposited Cretaceous rock basement. This deposition ended when the faulting starting around 56 million years ago and transformed the previously flat terrain into mountainous horst and graben terrain, which retained sediments within extensive basins on land. By 33 million years ago as sea levels declined Sumatra uplifted and increased the sediment supply within an inter-connected regional river system that deposited westwards from Malaysia. However, regional subsidence resulted in extensive regional submersion from 23 million years ago and cut off of the sediment supply. Following intense volcanism around 5 million years ago the Barisan mountains were uplifted in Sumatra once more depositing volcanic debris in the Straits of Malacca. Depositional processes were dominant on the Malay Peninsula throughout the most recent Quaternary period, especially in coastal areas. Hutchison and Tan (2009) divide the peninsula into denudational areas (>15m above sea level) where erosion removes materials and depositional terrains below that where sediments are collected.
Peninsula Malaysia is marked orographically by its mountainous interior orientated North to South (see Figure 1.22), including the Nakawan Range, Keddah-Singora Range, Bintang range, Kladang range, Titiwangsa Range (locally known as the Main Range), Benom Range, Tahan Range and East Coast range. The Titiwangsa Range is the “backbone of Peninsular Malaysia” and demarcates the Bentong-Raub suture, created when the Sibumasu and Indochina collided 200 million years ago, and is composed mostly of granite. The Main Range has an average width of 45-65 km and is continuous for around 480km, most of its peaks forming the border between Pahang and Selangor. Phyllite enclaves can be observed at Gunung Korbu (Figure 1.24) which rises 2184 metres. There are also some excellent examples of roof pendant in parts of the Titiwangsa range. Malaysia’s most famous mountain, Kinabalu, the highest in Southeast Asia, is composed of layers of rocky sandstone and shale formed under the sea 35 million years and uplifted to the Crocker Range which runs through East Malaysia.
Limestone occurs widely throughout Malaysia, often observed as steep and abruptly rising formations known an mogotes which are common around Langkawi Island (Tan, 1998). The Nakawan Range is the longest continuous limestone hill in Malaysia and the boundary with Thailand. Karst is developed over bedrock undergoing solution by downward percolating meteoric water (Tan, 2009, p.9). Steep sided limestone hills are very common around Ipoh, rising abruptly over the surrounding flat land. Hills such as these are normally honeycombed by caves and have deeply pitted surfaces. Both peninsula and Malaysian Borneo contain caves giving insight into geological structure and process (see Figure 2.24).
Granite is omnipresent in Peninsular Malaysia as the following brief naming of some of the principal ranges shows. As usual, clicking any blue link or highlighting any text will allow rapid exploration of concepts in order to answer questions as they occur to you, in this particular theme Google Maps will be helpful. The Kedah-Singgora Range consists of quartzite with granite outcrops, an outlier of this range being granite Penang Island. The Bintang Range, with peak Gunung Bintang at 1860 metres is also of granite. Around Enggor in Northern Perak, The Kledang Range is also granite and is an offshoot of the Main Range which, whilst predominantly granite has enclaves of meta sedimentary rocks such as phyllite. The Main Range has an average width of 45-65 km and is continuous for around 480km, most of its peaks forming the border between Pahang and Selangor. One of the Main Range’s phyllite enclaves is at Gunung Korbu (Figure 2.25) which rises 2184 metres. The Benom range again is formed of granite, the Tahan range of folded sedimentary rocks mainly quartzite, sandstone and shale. Finally The East Coast range extends from the Kelantan Coast in the north to Sungai Pahang in the south, being marked by highly dissected deep and narrow valleys at an average of 762 metres above sea level.
In the humid tropics, granite has the characteristics of being commonly broken down to a granite sand or a red quartz-bearing clay and exhibts sharp transitions between fresh and weathered rock with widespread survival of core stones and boulders. Thus the Malaysian geological landscape includes limestone, sandstones and granites and has been affected greatly by precipitation over geological time. This is also the case in Malaysian Borneo, geologically part of the Sunda Shelf (see Figure 2.26) upon which Peninsula Malaysia and Indonesia sit.
Malaysian Borneo (Figure 2.27) is classified into the Miri Zone, dominated by miogeosynclinal and molasse strata, the Sibu Zone, dominated by eugeosynclinal flysch; the Kuching Zone, of basement complex and molasse and the West Borneo Basement dominated by Cretaceous volcanic and plutonic rocks (Hutchison, 2005).
Karst is developed over bedrock undergoing solution by downward percolating meteoric water (Tan, 2009, p.9). In this region it often can be seen as steep sided limestone hills rising abruptly over the surrounding flat land. Hills such as these are normally honeycombed by caves and have deeply pitted surfaces. Both peninsula and Malaysian Borneo contain caves giving insight into geological structure and process (Figure 2.29).
Another such cave complex, Batu Caves, is near Malaysia’s capital Kuala Lumpur. Batu Caves is one of only two areas (the other being Bukit Anak Takun) where Kuala Lumpur limestone and marble are exposed above ground level. The limestone that forms the caves is likely corals of mid-Silurian age (410-435 million years ago). Batu Caves is this week’s recommended excursion.
This topic promotes exploration of geological time, the formation of the earth and the appearance of humans. Plate tectonics and their relationship to Asia, Malaysia and global patterns of vegetation have been explored. Sea and water changes and cycles have been linked to vegetation processes. Extra-terrestrial activity has been shown to effect the earth from time to time in significant ways. Malaysia’s topography and formation, including mountain ranges and caves, has been introduced.