Geological Heritage sites of India

Geological agents like wind, water, ice act continuously on the rocks to erode and transport the disintegrated rock materials, bringing out marvellous changes in landscape. Natural Arch is one such unique geological marvel in the country measuring 8 metres in width and 3 metres in height. It has been curved out of quartzite of Cuddapah Supergroup of Middle to Upper Proterozoic (1600 to 570 Ma) by collective action of weathering agents like water and wind over a long period of several thousands of years.

 Natural Arches of this kind are a rarity. The Rainbow Arch of Utah in the USA and the one in the Dalradian Quartzite are the other examples.

Erra Matti Dibbalu are rare red sand dunes and carry with them millions of years of geological processes. The dissected and stabilized coastal red sediment mounds are located between Vishakhapatnam and Bhimunipatnam. The dunes comprise a light yellow sand dune at the top followed by a brick red sand unit, and a reddish-brown concretion bearing sand unit with yellow sand at the bottom. However, the dunes are very fragile and are vulnerable to natural degradation. 

Laterite in Angadipuram has been derived from acid charnockite. The crystalline rocks of this region are an admixture of pyroxene granulite, charnockite and migmatite. The laterite here occurs at an average elevation of 60 m above m.s.l. Laterite is significant from the economic angle since mineral deposits of aluminium ore (bauxite), iron ore and nickel ore are known to be associated with them

The cliff, including both northern and southern ones, covering a total distance of 3 km exposes the sedimentary rock formation of the Mio-pliocene Age. As per GSI, Varkala was the only place in the west coast of India where sediments in the Mio-Pliocene Age (around 25 million years ago) had been exposed.

National Fossil Wood Park, Tiruvakkarai, Villupuram District, Tamilnadu. Here 200 fossil trees ranging in length from 3-15 m and upto 5 m in girth are seen lying horizontally embdedded in Cuddalore Sandstone of Mio-Pliocene age (Ca 20 m.y.)

National Fossil Wood Park in Sattanur, Perambalur District contains large trunks of petrified trees of Upper Cretaceous age (100 m.y). The trees belong to conifers (non-flowering) that dominated the land vegetation during the period. The fossilised tree trunk at Sattanur measures over 18 m in length.

Charonockite, St. Thomas Mount, Chennai is a typical exposure of quartz-feldspar-hypersthene rock, characterized by presence of two pyroxene facies metamorphism. The name 'Charnockite' originated from the use of the same rock as tombstone of Job Charnock, the founder of Kolkata. The constituents of the rock suggest of its origin in particularly 'dry' and high temperature condition and believed to have important bearing in elucidating primordial crustal evolution of the earth. 

The Karai Formation of Uttatur Group at Karai-Kulakkalnattam section in
Perambalur district forms the lower part of the Cretaceous sedimentary succession of the Cauvery Basin. The Karai Formation is exposed as badlands with a series of conical mounds separated by gulleys

Eddy Current Markings at Panchmahal district, Gujarat are exposed in sedimentary (sandstone) surface of Upper Aravalli Lunavada Group of rocks. These marks are believed to result from dragging of a small limb of a larger floating log caught in a vortex or eddy current of a stream or from a movement of a pebble. The petrified marks of the eddies around the whirl balls, form spiralribs.

It is a unique example of nature's capacity as a sculptor. Sendra granite, a plutonic igneous rock of about 900 m. y. ago, intrudes into the Delhi Supergroup of metasedimentary rocks. Large bosses are concordantly emplaced in the calc‐ gneiss while small bodies are mostly distributed in and around the hornblende schists.

 Wind and water acting over thousands of years, has sculpted the granite into marvellous structures that have inspired man through ages.

Barr Conglomerate, Pali District, Rajasthan composed of pebbles of quartzite and rarely granite gneiss, set up in a fine grained pelitic matrix. It rests unconformably above the basement gneiss in the vicinity of Barr. Conglomerates are important in geology as they aid in subdividing geologic history on the basis of sedimentary breaks.The conglomerate is best exposed on either side of the Bewar‐ Sendra‐ Barr‐ Pali road but just before Barr‐ Pali cross road towards Sendra.

The pebbles are stretched to an extraordinary extent, about 20 to 30 times its original dimension.

Stromatolite Park, Jhamarkotra, Udaipur District, Rajasthan is the largest & richest deposit of phosphorite associated with stromatolite. It is another site preserving evidences of early life on the earth. The stromatolites occurs over a strike length of 15 km in rock phosphate within Precambrian Aravalli Supergroup of rocks. The rock phosphate occurs in dolomitic limestone associated with stromatolites appearing in grey to bluish grey colour shades and in variable forms and shape.

This gossan led to rediscovery of Rajpura‐ Dariba mineralised zone. It has formed due to extensive chemical weathering and pervasive oxidation of the suplhides‐ sulphosalts ore bodies through prolonged geological periods under favourable climatic condition. The gossans show a variety of colours including reddish brown, brown, dark brown, bluish green, white and grey and also different type of boxworks. The chief ore minerals are sphalerite, galena and chalcopyrite. Zinc is the dominant base metal followed by lead and copper.

Stromatolite Park, Bhojunda, Chittaurgarh District, Rajasthan is an exposure within the massive Bhagwanpura Limestone of the Lower Vindhyan age. Stromatolites are structures produced by blue-green algae, which through their filaments, attract and bond carbonate particles forming a mat. They are stratiform, columnar and nodular structures in carbonate rocks resulting from the combination of life activity and sediment trapping and binding ability of algal assemblages and preying bacteria. They form generally in shallow water where tides bring floating sedimentary material continuously and make it flow through carbonate particles. Stromatalites are known as impression of one of the earliest form of life on earth.

Akal Fossil Wood Park, Jaisalmer District is a wonder for the tourists who know that Jaisalmer as a part of the great Thar desert. The petrified wood carries signature of the luxuriant forests in a warm and humid climate, bordering the sea some 180 m.y. ago. The 21 hectar Fossil Park contains about a dozen fossil wood logs lying horizontal in random orientation. The longest specimen is 13.4 m x 0.9 m. The fossils are of petrophyllum, ptyllophyllum, equisetitis species and dicotyledonous wood and gastropod shells of Lower Jurassic period.

Nepheline Syenite, Kishangarh, Ajmer District, Rajasthan is a pluton emplaced along the core of an antiform of metamorphites in Aravalli craton of Rajasthan. Kishangarh syenite, by which the unit is also called has been dated 1590 million years to 1910 million years.

Welded Tuff, Jodhpur District, Rajasthan in the Jodhpur Fort hill area occurs within the terrace like weathered Malani volcanics.

The welded tuff, is a product of emanations, that spurted out from volcanic vents and were carried away by air to settle down. They are composed of glass, quartz and feldspar. On cooling they develop joints which which gives rise to columns and terraces.

 The Malani rhyolites comprise pink, maroon, brown, purple, grey and green rhyolite separated by tuff, welded tuff and pyroclastic rocks. The columnar joints developed are rectangular to hexagonal, attaining a length of 30m or more at places. It is overlain by deep purple coloured porphyritic rhyolite.The pyroclastics are intermixed with lava representing the final phase of emanations.

Jodhpur Group‐ Malani Igneous Suite Contact, Jodhpur District, Rajasthan lies at the foot of the picturesque Mehrangarh Fort within the Jodhpur city. The igneous suite marks the last phase of igneous activity of Precambrian age in the Indian Subcontinent. The rock is characterised by purple to red and ash coloured laminated tuff with chocolate coloured chalcedony, dark red obsidian, purple, reddish, buff, whitish and greyish coloured rhyolitic tuff related to ignimbrite. The contact is enhanced by the multi‐coloured igneous suite in contact with light coloured Jodhpur sandstone.

Great Boundary Fault at Satur, Bundi district, Rajasthan is characterised by a faulted boundary between Pre-Aravallis and Upper Vindhyans having NNW‐SSE trend. It represents a zone of disruption constituted by a number of parallel and oblique faults resulting in a step like feature. Deformed limestone at the site is worth viewing

The 3.5 km diameter creater is an eye pleasing geomorphic feature, which also has biotic, spiritual and archaeological heritage attributes. Located in a tropical area it has a forest that is protected by the environmental laws of the land and the commandments of spiritual faith of a Dev-Vanee (sacred grove).

Lonar Lake, Buldana District is a nearly circular crater, suspected to have developed due to impact of a large meteorite on Deccan Basaltic rocks of Cretaceous age. A meteorite is a recovered fragment of natural object orbiting in space, that has survived transit through the earth's atmosphere. Such hypervelocity large meteoritic impacts on earth produces craters. Approximately 130 terrestrial craters are currently recognised, ranging in size up to several hundred kilometers in diameter and age upto 2 Ga. The Lonar Crater has an average diameter of 1710 m, average rimheight of 40 m and depth of 230‐ 245 m. The circular depression bears a saline water lake in its central portion

Marine Gondwana Fossil Park at Manendragarh, Sarguja district, Chattisgarh is an unique exposure of fossiliferous marine Permian (280‐ 240 Ma) rocks of Talchir Formation belonging to Gondwana Supergroup. It is exposed for a length of about one km upstream to the confluence of Hasdeo River and Hasia nala. The marine fauna is represented by the dominance of pelecypods/ lamellibranchs like Eurydesma and Aviculopecten within shale, besides Bryozoans, Crinoids and forminifers.

Columnar Basaltic Lava, Coconut Island (St. Mary's Islands), Udupi District, Karnataka displays majestic array of multi-faced columns developed in the basalts of Deccan Trap. These marvelous structures, called Columnar Joints in geological parlance are nature's exquisite handiwork. The geometrical form of the rock mosaic resembles the work of an expert sculptor.

The Deccan Trap, evolved due to vast outpouring of hot molten basaltic lava in the western part of India during Cretaceous‐ Eocene time (about 60 million years ago) are now present as flat topped hills and step like terraces.

Pillow Lava, Maradihalli, Chitradurga District, Karnataka, hosted within Chitradurga schist belt of Dharwar Group, is one of the best of its kind in the world. They are formed when hot molten lava erupts under water and solidifies in the form of roughly spherical or rounded pillow-shape. The lava gets chilled so suddenly that part of the flow separates into discrete rounded bodies a few feet or less in size. This pillow lava has been dated 2500 million years.

Gneisses and related granitoids constitute one of the most abundant rocktypes exposed on earth.

The Lalbagh hill is composed of dark biolite gneiss of granitic to granodioritic composition containing streaks of biolite. Vestiges of older rocks are seen in the form of enclaves within the gneiss.

Peninsular Gneiss of the region is dated 2500 to 3400 million years that accreted in three major episodes, i.e. 3.4 Ga, 3.3-3.2 Ga and 3.0-2.9 Ga. The quarries of Lalbagh are of great importance for researches on earth sciences towards evolution of the terrain.

The term 'pyroclastic' literally means broken by fire. The particles ejected from a volcano during explosive activity vary considerably in size and composition. All these ejected material consolidate to form pyroclastic rocks.

Pyroclastic Rocks in Peddapalli is a welded agglomerate of large fragments of granite, granite gneiss, basalt and banded ferruginous quartzite set in a matrix of ignimbrite. While many rock fragments are angular some of them appear to be well rounded. Some rock fragments of granite gneiss measure upto 80 cm in diameter.

Sirmur District

The Siwalik Fossil park displays a rich collection of vertebrate fossils recovered from the Siwalik rocks of the area of Plio-Pleistocene age. The deposition of Siwalik sediments took place in the narrow linear depression, called the 'fore deep', which started developing in front of the Himalayas since the inception of its uplift in the middle Miocene

Nomira, Keonjhar dist.

Pillow Lava, Iron ore belt, Nomira, Keonjhar District, Orissa is an exposure of well-preserved pillow structures. Individual pillows are roughly ellipsoidal and closely packed with a maximum thickness of 2m x 0.6m. The basic lava is fine to medium grained, green to bluish green coloured with abundant vesicles filled with quartz. The lavas and the associated pyroclastics and tuffs are underlain by quartzite and overlain by shale, chart‐ shale and banded hematite jasper.

Upper Gondwana sequence around Mandro, Sahibganj dist.

Gondwana Supergroup comprises a thick sequence of fluviatile and lacustrine
sediments having a cumulative thickness of about 6 to 7 km with glacial
sediments at the base.  The Gondwana sequence is largely
considered as a continental sedimentary sequence with occasional marine
incursions and deposited either in the river valley grabensor in the down-faulted grabens.

Site near Pungro,

Stromatolite bearing Dolomite / Limestone of Buxa

Formation Mamley, near Namchi, South District

The Geoheritage site at Mamley exposes lithounits of Buxa Formation, Daling Group of Proterozoic age. The dolostones are profusely stromatolitic (Precambrian algal structures). This site provides one of the rare examples of early life in Sikkim Himalaya.