Here is your paragraph on the Dravidian rock system (Palaeozoic) of India:
The rocks of the Dravidian system came into being about 600-300 million years ago.
Most rocks of this system are found in the Extra Peninsular region and they are conspicuous by their absence in the Peninsular India except for one or two small patches of lower Permian age near Umaria.
The Cambrian and Devonian rocks containing recognisable fossils are unknown in the Peninsula. The rocks belonging to the Dravidian System contain abundant fossils which help in determining correctly the age of the rocks and make correlation of rocks possible over distant areas. The rocks of Cambrian, Ordovician, Silurian, Devonian and Carboniferous periods are included in the Dravidian system.
ADVERTISEMENTS:
The Cambrian rocks (600 million years) named after Cambria the Latin name for Wales in Great Britain; include slates, clays, quartzites and limestones. They are best developed in the North West Himalayan region. In the Spiti valley of Himachal Pradesh, there is an extensive fauna known as the Haimanta System.
This 1600 metre thick deposit consists of slates, quartzites and dolomites. Similar formations are found north of Kullu and Lahul in Himachal Pradesh as well as in the Baramula district of Jammu and Kashmir. In Kurtiaon, some slaty and sandy rocks of the Cambrian period are found.
ADVERTISEMENTS:
In the salt range on the Indo-Pak border, the Cambrian is represented by 900 metres of fossiliferous sandstones, shales and dolomites underlain by salt marl (clayey salt) known as the saline series.
The Ordovician rocks after the Ordovices, former inhabitants of Wales (500 million years) include quartzites, grits, sandstones and limestones. They overlie the Haimanta system in all parts of the Spiti in the form of a thick series underlain by conglomerates. They are also present in the Lidar valley of Kashmir and in the Kumaon region.
The Silurian rocks after the Silures, former inhabitants on the borders of Wales and England (440 million years). In the Spiti valley, the Silurian rocks are in continuation with the Ordovicians. Round the core of the Lidar anticline there runs a thin but continuous band of Silurian strata. The Lahul and the Kullu valleys of Himachal Pradesh also have some Silurian deposits. The limes and shales of the Kumaon region belong to the Silurian period.
The Devonian rocks after Devonshire in England (400 million years) are a great thickness of massive white quartzite reaching a thickness of 900 m at certain places. They are devoid of any fossil remains. These rocks have definitely been identified in the Muth quartzite of Spiti and Kumaon, on the flanks of Lidar anticline and in the Haridwar district of Uttaranchal.
The Carboniferous rocks (350 million years) comprise mainly of limestone, shale and quartzite. These rocks are generally divided into the Upper Carboniferous, Middle Carboniferous and Lower Carboniferous systems. The Upper Carboniferous rocks are made of limestone and dolomite. Mount Everest is composed of Upper Carboniferous limestones.
The Middle Carboniferous has been the age of great upheavals. The rocks of this group are mainly found in the Spiti valley, Kashmir, Shimla and in the eastern Himalayas. In the Lower Carboniferous group are included slates of different types, Pir Panjal trap, and some rocks of the Kumaon region. Coal formation started in the Carboniferous age. Carboniferous in Geology means coal bearing.