Geomorphology

Sedimentary rocks are formed by the accumulation of sediments. There are
three basic types of sedimentary rocks.
•Clastic sedimentary rocks such as breccia, conglomerate, sandstone, siltstone,
and shale are formed from mechanical weathering debris.
•Chemical sedimentary rocks, such as rock salt, iron ore, chert, flint,
some dolomites, and some limestone, form when dissolved materials precipitate
from solution.
•Organic sedimentary rocks such as coal, some dolomites, and some limestone,
form from the accumulation of plant or animal debris.

Dharwar system is later than the Archean system but older than the other systems.
• The Dharwar period of rock formation has been largely fixed from 2500 million years ago to 1800 million years ago.
• Dharwar Rock System is special because it is the first metamorphic sedimentary rocks in India.
• They are named Dharwar system because they were first studied in Dharwar region of Karnataka.
• But they are also found in Aravallis, Tamil Nadu, Chota-nagpur plateau, Meghalaya, Delhi, and the Himalayas region.
• The Dharwar rocks are rich in iron ore, manganese, lead, zinc, gold, silver etc.

Igneous Rocks – produced by solidification of molten magma from the mantle. Magma that solidifies at the Earth’s surface conceives extrusive or volcanic igneous rocks.
When magma cools and solidifies beneath the surface of the earth intrusive or plutonic igneous rocks are formed
Characteristics of Igneous rocks are:
• Formed by the cooling and solidification of lava.
• Hard in nature.
• Consists of crystals, hence also called as crystalline rock.
• Examples are Granite and Basalt. These rocks are formed inside as well as on the earth.
• Fossils are not present in this rock.
• Igneous rocks are of two types : a. Extrusive rocks b. Intrusive rocks
• It is non porous rock.

NOTE: Sedimentary rocks are most widespread on the surface of the earth and constitute about 75% of the surface area of globe.

Sedimentary rocks are formed by the accumulation of sediments. There are three basic types of sedimentary rocks.
• Clastic sedimentary rocks such as breccias, conglomerate, sandstone, siltstone, loess and shale are formed from mechanical weathering debris.
• Chemical sedimentary rocks, such as rock salt, iron ore, chert, flint, some dolomites, and some limestone, form when dissolved materials precipitate from solution.
• Organic sedimentary rocks such as coal, some dolomites, and some lime stones, form from the accumulation of plant or animal debris.

The Crust is the outermost solid part of the earth. It is brittle in nature. The thickness of the crust varies under the oceanic and continental areas.
• Oceanic crust is thinner as compared to the continental crust. The mean thickness of oceanic crust is 5 km whereas that of the continental is around 30 km.
• The continental crust is thicker in the areas of major mountain systems. It is as much as 70 km thick in the Himalayan region.
• The average density of oceanic crust is 3.0 g/cm3, while continental crust has an average of 2.7 g/cm3.

Igneous rocks may be subdivided on the basis of mineral composition.
• When they contain a high proportion of silica they are said to be acid.
• Acid igneous rocks, such as granite, are less dense and are lighter in colour than basic rocks.
• These contain a greater proportion of basic oxides, e.g. of iron, aluminum or magnesium, and are thus denser and darker in colour.

Kilauea is the youngest and most active Hawaiian shield volcano, located on the southern part of the Island of Hawai’i, known as Big Island. Since 1952, Kīlauea has erupted 34 times. From 1983 to 2018 eruptive activity was nearly continuous along the volcano’s East Rift Zone.
Hawaii’s Kilauea volcano erupted 20th December 2020. The eruption occurred within the Halema’uma’u crater. A magnitude 4.4 earthquake followed the eruption.

The Bureau of Indian Standards has classified regions in India into four seismic zones on the basis of historical seismic activity.
• These are zones II, III, IV and V. Among these, Zone V is the most seismically active region and zone II is the least active.
• According to Modified Mercalli scale, the seismic zone intensity is/are classified as zone II (low intensity zone), zone III (moderate intensity zone), zone IV (severe intensity zone) and zone V (very severe intensity zone).

According to the Ministry of Earth Sciences:

•Zone V includes entire northeastern India, parts of Jammu and Kashmir and Himachal Pradesh, Uttaranchal, Rann of Kutch in Gujarat, parts of North Bihar and Andaman & Nicobar Islands.
• Zone-IV includes the remaining parts of Jammu and Kashmir and Himachal Pradesh. Delhi-NCR region, Sikkim, northern parts of Uttar Pradesh, Bihar and West Bengal, parts of Gujarat and small portions of Maharashtra near the west coast and Rajasthan also fall in this zone.
• Regions under zone III are Goa, Kerala, Lakshadweep, and remaining parts of Uttar Pradesh, Gujarat and West Bengal, parts of Punjab, Rajasthan, Madhya Pradesh, Bihar, Jharkhand, Chhattisgarh, Maharashtra, Orissa, Andhra Pradesh, Tamilnadu and Karnataka.
• The remaining portion of the country falls under zone II.

The main geographic sections of the Kashmir Himalayan range are the Pir
Panjal, Kashmir Valley, Zanskar, Ladakh and Karakoram

The Himalayas bend sharply to the south beyond the Dihang gorge and move
outwards to form a covering the eastern boundary of the country. They are known as ‘the
Eastern or Purvanchal Hills’.
•Daffla Hills: It is situated to the north of the Tezpur and North Lakhimpur, and is
bounded on the west by the Aka Hills and on the east by the Abor Range.
•Mishmi Hills: These hills are located in the southward extension of the Great
Himalayan ranges and its northern and eastern parts touches China.
•Mikir Hills: It is located to the south of the Kaziranga National Park. It is part of the
Karbi Anglong Plateau. Radial drainage pattern is the best characteristic of this
region where Dhansiri and Jamuna being the main rivers.
•Jaintia Hills: It is located further to the east from the Khasi Hills.

Statement 1 is correct. An aquifer is a body of saturated rock through which water can easily move. Groundwater enters an aquifer as precipitation seeps through the soil. It can move through the aquifer and resurface through springs and wells.
Aquifers must be both permeable and porous and include such rock types as sandstone, conglomerate, fractured limestone and unconsolidated sand and gravel. Fractured volcanic rocks such as columnar basalts also make good aquifers.
Statement 2 is correct. An artesian well is simply a well that doesn’t require a pump to bring water to the surface. This occurs when there is enough positive pressure in the aquifer to bring the water to the surface.
Groundwater in aquifers between layers of poorly permeable rock, such as clay or shale, may be confined under pressure. If such a confined aquifer is tapped by a well, water will rise above the top of the aquifer and may even flow from the well onto the land surface. Water confined in this way is said to be under artesian pressure, and the aquifer is called an artesian aquifer.
# A Memorandum of Agreement (MoA) was signed recently between Central Ground Water Board and CSIR-NGRI, Hyderabad for geophysical survey and other scientific studies in North-Western India under the Aquifer Mapping Programme.

Both statements are incorrect.
Recently the Foreign Ministers of Nepal and China jointly certified the elevation of Mount Everest at 8,848.86 metres above sea level — 86 cm higher than what was recognised since 1954.
The elevation of 8,848 m was determined by Survey of India in 1954. In 1999, a US team put the elevation at 29,035 feet (nearly 8,850 m). This survey was sponsored by the National Geographic Society, US.

Atlas Mountain Range: The Atlas Mountains are a mountain chain located in
North Africa.
•The Atlas mountain chain stretches across North Africa through Algeria, Tunisia,
and Morocco.
•The mountains formed over millions of years, gaining their present-day shape when
the African continent collided with the Iberian peninsula, in what is known as
a convergent plate boundary.
•Because of their extensive range, the Atlas Mountains are divided into seven
different sub-regions, each with their own unique ecosystem.
•Overall, however, the Atlas can be categorized as a semi-arid mountain range
between the tropical waters of the Atlantic Ocean/Mediterranean and the
massive Sahara Desert.
•The highest mountain in the Atlas is Mount Toubkal. Mount Toubkal measures
nearly 14,000 feet, and is located in southwestern Morocco.
New England Range: New England Range, also called New England Tableland, or Northern
Tableland, section of the Eastern Highlands, or Great Dividing Range, northeastern New
South Wales, Australia.
•The range extends 200 mi (320 km) north from the Moonbi Range (near Tamworth)
to the Queensland border and 80 mi from east to west (10–50 mi inland from the
coast).
•It is Australia’s largest plateau, having 9,000 sq mi (23,000 sq km) above an
elevation of 3,000 ft (900 m).
Cantabrian Mountain: The Cantabrian Mountains or Cantabrian Range are one of the
main systems of mountain ranges in Spain. They stretch for over 300 km across northern
Spain, from the western limit of the Pyrenees to the Galician Massif in Galicia, along the
coast of the Cantabrian Sea. Their easternmost end meets the Sistema Ibérico.

Fold Mountains are created through a process called orogeny. An orogenic
event takes millions of years to create a fold mountain.
•When a tectonic plate gets pressure from two sides, it gets folded. Some of its
portion becomes elevated and forms the mountains.
•The depressions form the valleys. The Himalayas, the Rockies, the Andes and the
Alps are examples of Fold Mountain.
•They are the young mountains of the world and hence they have some of the highest
peaks of the world.

A caldera is a large depression formed when a volcano erupts and
collapses.
•During a volcanic eruption, magma present in the magma chamber underneath the
volcano is expelled, often forcefully.
•When the magma chamber empties, the support that the magma had provided
inside the chamber disappears.
•As a result, the sides and top of the volcano collapse inward. Calderas vary in size
from one to 100 kilometers (0.62 to 62 miles) in diameter.
•Some calderas form a lake as the bowl-shaped depression fills with water. A famous
example is Crater Lake, in Oregon.
•This caldera formed about 7,000 years ago when a stratovolcano, Mt. Mazama,
violently erupted.
•For several thousand years after this eruption, smaller volcanic eruptions continued
inside the caldera.
•One of these eruptions was so large it formed an island in Crater Lake named
Wizard Island.

Indus Tsangpo suture is a tectonic suture in southern Tibet and across the
north margin of the Himalayas which resulted from the collision between the Indian plate
and the Eurasian plate.
Himalayas are known to be made up of north dipping thrusts like the Main Central
Thrust (MCT), the Main Boundary Thrust (MBT), and the Main Frontal Thrust (MFT).
As per the established models, all of these thrusts except MFT are locked, and overall
deformation in Himalaya is being accommodated only along with the MFT.
Recently, a group of Scientists from Wadia Institute of Himalayan Geology (WIHG),
Dehradun have observed that suture zone of the Himalayas or the Indus Suture Zone (ISZ) in the Ladakh region where Indian and Asian Plates are joined has been found to be
tectonically active, as against current understanding that it is a locked zone.

The Nazca plate is an oceanic tectonic plate in the southeastern Pacific Ocean that shares both convergent and divergent boundaries, corners multiple triple junctions, contains three seamount chains, overrides four hotspots, and is responsible for the creation of the Andean orogeny.
• Over the last half-century, it has garnered much attention from the scientific and political community due to the hazards it poses to the populated west coast of South America.
• With oblique subduction underneath the South American plate, this active convergent margin is the longest subduction zone in the world, stretching 7500 km and produced the largest earthquake ever recorded on earth, the M 9.5 Valdivia earthquake.

Earthquake waves are basically of two types — body waves and surface waves. Body waves are generated due to the release of energy at the focus and move in all directions travelling through the body of the earth. Hence, the name body waves.
• The body waves interact with the surface rocks and generate new set of waves called surface waves. These waves move along the surface.
• The velocity of waves changes as they travel through materials with different densities. The denser the material, the higher is the velocity.
• Their direction also changes as they reflect or refract when coming across materials with different densities.
• There are two types of body waves. They are called P and S-waves. P-waves move faster and are the first to arrive at the surface. These are also called ‘primary waves’.
• The P-waves are similar to sound waves. They travel through gaseous, liquid and solid materials.
• S-waves arrive at the surface with some time lag. These are called secondary waves. An important fact about S-waves is that they can travel only through solid materials.

Anamudi is a mountain located in the Indian state of Kerala.

 It is the highest peak in the Western Ghats and South India, at an elevation of 2,695 metres.

 Its parental hills are Anaimalai hills.

 Doda beta is the highest peak of nilgiri hills while Guru Shikhar is the highest peak of Aravali Range located in Rajasthan.

The White Island Volcano, also called Whakaari, in New Zealand has recently erupted.

 White Island is New Zealand’s most active cone volcano.

 About 70% of the volcano lies under the sea.

 It is the country’s most active volcano situated in the east coast in the Bay of Plenty.

Nioghalvfjerdsfjorden or 79N is roughly 80km long by 20km wide and is the floating front end of the Northeast Greenland Ice Stream – where it flows off the land into the ocean to become buoyant.

At its leading edge, the glacier splits in two, with a minor offshoot turning directly north. It’s this offshoot, or tributary, called Spalte Glacier, that has now disintegrated.

The ice feature was already heavily fractured in 2019; this summer’s warmth has been its final undoing. Spalte Glacier has become a flotilla of icebergs.

When the soil is completely saturated with water the individual particles are

almost suspended in the water and move easily over one another and over the underlying

rock. The soil acts like a liquid and a soil-flow occurs.

In areas of peat soils, the peat absorbs much moisture. However if saturation point is

reached the peaty soil may flow down-slope. In Ireland such flows are known as bogbursts.

The costal land forms of east and west coasts of the Nation contain significantly important placer mineral deposits.

 The minerals like ilmenite, rutile, garnet, zircon, monazite and sillimanite are occurring in these deposits.

 The controls like source rock geology, coastal geomorphology effective drainage network and favorable climatic conditions favored the formation of rich placer deposits in coastal environments.

 Important deposits occur in the coastal environments of Kerala (Chavara), Tamil Nadu (Manavalakurichi, Midalam, Vayakallur), Andhra Pradesh (Kakinada, Pentakota, Bhimunipatnam, Konada – Kandivalasa – Mukumpeta – Bendi creek – Donkar), (Sanaekasangi – Gopalpur, Chatrapur, Bajarkot, Satpara and Puri) and Maharastra (Kalbadevi, Newre and Malgund).