Khursheed Dinshaw (India)
The Akal Wood Fossil Park is located about 18km from the desert city of Jaisalmer in Rajasthan, India. It has preserved fossil evidence dating back to the Jurassic Period (Fig. 6) indicating a hot and humid climate characterised by dense forests. In particular, 180-million-year-old fossils of animals and plants are preserved here.
The Jaisalmer Basin formed part of the southern shelf of the Tethys Ocean during Jurassic times. The area is well known for its rich geo-diversity, both in terms of landscapes and outcrops of rock types, and the variety of fossils that these rocks have preserved. When I spoke to him, Dr Sudesh K Wadhawan, who is Adviser (Geosciences) and Visiting Faculty, Director General (Retired), Geological Survey of India, explained that, “Lithostratigraphy of the geologically mapped formations displays an array of Jurassic siliciclastic, mixed carbonate-siliciclastic and carbonate rocks that range in age from Lower Jurassic to Upper Jurassic in geological timescale. A variety of depositional environment, ranging from continental fluvial to near-shore and off-shore deep marine, are interpreted and well documented in the Jaisalmer basin”.
The fossil logs, representing gymnosperms, belong to the dicotyledonous stems of these trees (Figs. 7 and 8). (In such stems, the vascular bundles are arranged in a ring, with pith concentrated at their core, rather than being scattered throughout the plant interior.) The sandstone also preserves the leaf impressions of Petrophylum and Ptilophyllum sp. Some thin beds of lignite are also found buried in the sandstone, belonging to the Lathi Formation of Lower Jurassic age.
About a dozen of the petrified logs, which are old silicified tree trunks, occur randomly embedded within the coarse, clastic sediments laid down in near horizontal disposition in a warm and humid fluvial environment bordering the sea, during the Lower Jurassic period. Here, the rocks comprise a sequence of conglomerates and sandstones unconformably overlying the Precambrian basement rocks of the Malani Igneous Suite. The sandstone found here is also a very good aquifer for storing potable quality ground water in the region, which is otherwise a water-stressed, dry desert.
Dr Wadhawan, who has also been actively working for preserving and for creating awareness for the Akal Wood Fossil Park, described the area to me as follows: “The Lathi Formation is named after the village, Lathi, on the Pokaran-Jaisalmer road, where typical sections of the representative rocks of the Lathi Formation are exposed. The conglomerate at the base grades upwards into a coarse, ill-sorted arkosic sandstone [a detrital sedimentary rock, containing at least 25% feldspar] containing nodules of hematite and thin impersistent lenses of lignite. The Lathi Formation has a maximum thickness of 360m”.
Three years ago, he proposed to develop a national geopark in Jaisalmer and presented a scientific paper on the subject at the 35th International Geological Congress held in 2016 at Cape Town in South Africa entitled, Jaisalmer basin in Thar Desert: potential for developing a geopark in Rajasthan, west India (see https://www.americangeosciences.org/sites/default/files/igc/1770.pdf). He also participated in the deliberations on issues and challenges, and for evolving lasting mechanisms for the establishment of geoparks.
This fossil wood park was discovered by the Geological Survey of India and declared a National Geological Monument in 1977. It was maintained by the Geological Survey of India until 1985, before being handed over to the state government’s Forest Department. This park is now maintained by the authority of the Desert National Park under the control of the Chief Wildlife Warden for the Government of Rajasthan.
The highlight of this fossil park is the 180-million-year-old rock (Lathi Formation of Lower Jurassic age) that has fossilised tree trunks lying scattered in an area of 21 hectares in the company of invertebrate life remains, like gastropods and ammonites (Figs. 2, 3 and 4). When I spoke to him, Dr Pushpendra Singh Ranawat told me that “The longest specimen of the tree trunks preserved here is 13.4m long and 0.9m wide.
The presence of such lifeforms indicates that the area at that time had lush growth of forest in a humid climate. Quick burial of life in sediments of the then sea ensured their preservation and subsequent molecular replacement by silica to preserve the original shape and pattern of the lifeforms.” Dr Ranawat has also been working with Dr Wadhawan to spread awareness about Akal and is the retired Professor of Geology, Dean Student Welfare, Chairman of the University Sports Board, MLS University in Udaipur.
The fossilised logs have been protected by iron grill cages with overhead tin sheds (Figs. 1 and 5). Maintained as a geotourism site, the Akal Wood Fossil Park is open from March to October, from 8.00 am to 6.00 pm. During November to February, which are the winter months, it is open from 8.00 am to 5 pm. A nominal entry fee is levied. It is advisable to hire a private car to visit the fossil park, as the fossils are scattered over a large area and vehicles are permitted inside.
All photographs are by Khursheed Dinshaw.