GUEST BLOG BY STUDENT AMBASSADOR
ETHAN HARDIN (8TH GRADE):
The geology of India, unlike other countries, is very diverse. Believe it or not, India contains some rocks that date all the way back to the Eoarchean Era! The mineral deposits are very rich and they vary greatly. All of India’s impressive geological features can be classified into three regions, the Deccan Traps, the Gondwana, and the Vindhyan.
The Deccan traps covers most of Maharashtra, a part of Gujarat, Karnataka, Madhya Pradesh and barely covers Andhra Pradesh at all. The Deccan Traps are basically colossal province of igneous located on the Deccan Plateau of west-central India. The Deccan Traps are one of the largest volcanic features on Earth. They consist of multiple layers of solidified flood basalt that together are more than 2,000 m thick, cover an area of 500,000 km squared and have a volume of 512,000 km cubed. Originally though, it may have covered 1.5 million km.
The Gondwana and Vindhyan include within its fold parts of Madhya Pradesh, Chhattisgarh, Odisha, Bihar, Jharkhand, West Bengal, Andhra Pradesh, Maharashtra, Jammu and Kashmir, Punjab, Himachal Pradesh, Rajasthan and Uttarakhand. The Vindhya Range is a complex, discontinuous chain of mountain ridges, hill ranges, highlands and plateau escarpments in west-central India. Technically, the Vindhyas don’t form one single mountain range in the geological sense. The precise extent of the Vindhyas is loosely defined, and the title covered a number of distinct hill systems in the centre of India, including the one that is now known as the Satpura Range. Now, the term principally refers to the escarpment that runs north of and roughly parallel to the Narmada River in Madhya Pradesh, and its hilly extensions.
The major rocks in India from the Precambrian can be classified as either the Archean System, or the Dharwar System. The Archean System consists of gneisses and schists which are the oldest rocks found in India. The Dharwar System consists of mainly sedimentary rock of origin. These rocks are enriched in manganese and iron ore which represents a significant resource of these metals. They are also extensively mineralized with gold most notably the Kolar gold mines located in Kolar.
Rocks of the earliest part of the Cambrian Period are mostly a thick sequence of fossiliferous sediments. They are found in the Salt range in Punjab and the Spiti are in central Himalayas. In the Salt range, the stratigraphy starts with the Salt Pseudomorph zone, and has dolomites and sandstones. It is overlain by magnesian sandstones similar to the underlying dolomites.
In the Triassic the Ceratite beds, named after the ammonite ceratite, composed of arenaceous limestones, calcareous sandstones and marls. The Jurassic is majorly two distinct units. The Kioto limestone, extends from the lower the middle Jurassic. The upper Jurassic is represented by the Spiti black shales, and stretches from the Karakoram to Sikkim. Cretaceous rocks are cover an extensive area in India.
In the Tertiary Period, the Himalayan orogeny began, and the volcanism associated with the Deccan Traps continued. These rocks tend to have very valuable deposits of petroleum and coal. Sandstones of Eocene age are found in Punjab, which grade into chalky limestones with oil seepage. Further north in India are the rocks found in Simla, are divided into three series, the Subathu series consisting of grey and red shales, the Dagshai series comprising bright red clays and the Kasauli series comprising sandstones. Towards the east in Assam, Nummulitic limestone is found in the Khasi hills. Oil is normally associated with these.