Here is a compilation of essays on the ‘Gondwana Flora of India’ for class 11 and 12. Find paragraphs, long and short essays on the ‘Gondwana Flora of India’ especially written for school and college students.
Essay on the Gondwana Flora of India
Essay Contents:
- Essay on the Introduction to Gondwana Flora of India
- Essay on the Indian Gondwana Stratigraphy
- Essay on the Distribution of Indian Gondwana Rocks
- Essay on the Classification of the Gondwanas
- Essay on the Major Floral Distribution of Gondwanas
Essay # 1. Introduction to Gondwana Flora of India:
The name ‘Gondwana’, suggested by H. B. Medlicott (1872), is derived from the ancient tribal Dravidian Gond Kingdom of Madhya Pradesh ruled by Rani Durgabati during the reign of Akbar the Great. Later the term ‘Gondwana System’ was published by Ottokar Feistmantel (1876), comprising of continental rock formation with coal seams and fossil plants and animals of the Upper Palaeozoic as well as Mesozoic Eras.
Other scientists discovered similar continental rock formations with coal seams and fossils from faraway continents of the Southern Hemisphere like South America, South Africa, Antarctica, Australia, Madagascar and New Zealand. Thus, the concept ‘Gondwanaland’ (Fig. 1.98) was introduced by Edward Suess (1885) which was originally conceived by Blanford (1875).
It is believed that the Gondwana Era began after the second major period of earth revolution, the Hercynian Revolution during Upper Carboniferous. The Gondwanaland lasted up to the beginning of the Cretaceous when the third major revolution of earth i.e., the Alpine- Himalayan Revolution took place.
This gave rise to the concept of two supercontinents by Du Toit (1937), one forming the Northern continental mass, the Laurasia and the Southern continent Gondwanaland, separated by the great equatorial Tethys sea. Thus, the single landmass, Gondwanaland, existed, showing a clear floral continuity ranging in age from the Upper Carboniferous to the beginning of the Cretaceous, from bottom to the top.
There was free and easy migration of plants and animals in this land mass, exhibiting similarity in floral composition and climatic conditions. There was several local minor revolutions of earth that changed the pattern of flora or fauna of the region in some periods. Though, these minor revolutions did not affect the whole landmass and many of them must have been localised.
Essay # 2. Indian Gondwana Stratigraphy:
Gondwanaland existed from the Lower Permian to the Lower Cretaceous with a span of 225 m.y. The Gondwana system is comprised of continental deposits of conglomerates, sandstones, shales and coal measures of mainly fluviatile (river) and locustrine (lake) origin. Recent works also indicate the presence of some marine intercalations in the Gondwana sediments of central and east coastal India.
The sediments were deposited in trough-like basins, bounded on either side by older Archaean rocks which endured faulting. Archaean rocks protected the Gondwana deposits from denudation and thus preserved the sediments in their original horizontal stratification. There is a striking homogeneity of Gondwana sediments with a uniform alteration of sandstones and shales bearing coal seams.
Essay # 3. Distribution of Indian Gondwana Rocks:
The Gondwana rocks are mainly distributed in major river valleys of Peninsular India. These are — (i) Damodar valley, (ii) Sone-Mahanadi valley, and (iii) Wardha-Godavari valley. A few exposures also occur in the Eastern coast (e.g., Cauvery, Palar, Krishna-Godavari and Orissa), Western Rajasthan, Saurashtra and Kutch. The Gondwana Basins have been mentioned in Table 1.3.
In the extra-peninsular, some detached outcrops are found in northern India such as Punjab Salt Range and Kashmir; and also in the sub- Himalayan regions of Sikkim, Bhutan, Arunachal Pradesh and Assam. The extra-peninsular outcrops have been subjected to metamorphism, showing very poor fossil content.
Essay # 4. Classification of the Gondwanas:
The classification of Indian Gondwanas is a matter of controversy.
G. de Cotton (1917) and Fox (1931) divided the Gondwana system into two major divisions (Table 1.3). Lower Gondwana (Lower Permian to Lower Triassic) and Upper Gondwana (M. Triassic to L. Cretaceous) which are characterised by Clossopteris and Ptilophyllum floras, respectively.
Feistmantel (1876) and Vredenburg (1910) proposed a three-fold classification of Gondwana: Lower, Middle and Upper Gondwanas (Table 1.3) which are correspondingly equivalent to the Permian, Triassic and Jurassic. All the localities containing Lower Gondwana fossils, but bearing the lithological characteristics of the Upper Gondwanas such as Panchet, Pachmari, Parsona, Maleri etc. are retained in the Middle Gondwana (Table 1.3).
The Middle Gondwana is characterised by Dicroidium flora, present in between the Glossopteris and Ptilophyllum floras. Subsequently, most of the palaebotanists supported the three-fold division of Gondwana.
The sub-divisions of Gondwana system are further divided into various series and stages. There is no controversy regarding the division of Gondwana up to series. However, the controversy arises at the level of stages and horizons. The flora of Gondwana is arranged with reference to the time scale which begins with the Talchir and extends up to the Bansa, Pariwar and Bhuj Formations.
According to the period of dominance of the principal genus of the floral assemblage, the Gondwana can be classified into three divisions (Fig. 1.99):
1. Lower Gondwana:
This division shows predominance of the Glossopteris flora, during Permian period, in which the Talchir, Karkarbari, Barakar, Barren measures Raniganj, Motur, Hingir and Bijori Formations are included. Some elements of this division continues till the Middle Triassic.
2. Middle Gondwana:
This is characterised by the accession of Dicroidium and declining of Glossopteris flora (mixed flora) at the beginning of Triassic which extends up to the Upper Triassic with dominance of Dicroidium flora. In this division, Panchet, Kamthi, Pachmari, Maleri, Parsora, Bagra, Tiki, etc. Formations have been included.
3. Upper Gondwana:
This is characterised by the arrival of Ptilophyllum flora till the end of Gondwana era, ranging from Jurassic to Lower Cretaceous, in which Dubrajpur, Rajmahal, Kota, Jabalpur, Gangapur, Shivganga, Bhuj, Pariwar, etc., Formations are conveniently included.
There is overlapping of the three distinct floras where the elements of the dying flora crawl for some time amongst the evolving flora, thus, showing the floral continuity throughout the Gondwana period.
So, there is a gradual decline of one flora with the simultaneous evolution of the other, both in number of individuals and species. Even in a single flora, there is specific delimitation where certain species characterise the smaller units of bigger sub-divisions. Thus, the larger sub-divisions can further be divided into smaller units (Fig. 1.99).
Essay # 5. Major Floral Distribution of Gondwanas:
Lower Gondwana Flora:
The different plants (Fig. 1.100) recovered from the various stages of the Lower Gandwara are listed:
1. Pteridophytes:
(i) Equisetales : Schizoneura, Phyllotheca, Stellotheca.
(ii) Sphenophyllales: Sphenophyllum, Rani- ganjia, Trizygia.
(iii) Lycopodiales : Cydodendron.
(iv) Filicales : Gondwanidium, Pecopteris, Sphenopteris, Angiopteridium, etc.
2. Gymnosperms:
(i) Glossopteridales : Gangamopteris, Glossopteris, Rubidgea, Rhabdotaenia, Vertebraria, Scutum, Ottokaria, Glosso- theca, etc.
(ii) Cycadales: Pseudoctenis, Taeniopteris.
(iii) Cordaitales : Noeggerathiopsis, Eury- phyllum, Cardiocarpus, Samaropsis.
(iv) Ginkgoales : Psygmophyllum, Ginkgo- phyton.
(v) Coniferales : Buriadia, Barakaria, Dadoxylon, Araucareoxylon, Agathoxylon, Damudoxylon etc.
Middle Gondwana Flora:
The different plants (Fig. 1.101) recovered from the Middle Gondwana are listed:
1. Pteridophytes:
(i) Equisetales : Schizoneura.
(ii) Calamitales : Neo-Calamites.
(iii) Filicales : Pecopteris, Sphenopteris, Marianopteris Cladophlebis.
2. Gymnosperms:
(i) Glossopteridales : Glossopteris, Macro- taeniopteris, Vertebraria, Dictyopteridium.
(ii) Corystospermales : Dicroidium.
(iii) Cycadales: Pseudoctenis, Taeniopteris.
(iv) Cycadeoidales : Pterophyllum, Zamites, Podozamites.
(v) Cordaitales : Neoggerathiopsis, Cardio- carpus, Samaropsis.
(vi) Coniferales : Araucarites.
Upper Gondwana Flora:
The major floral distribution (Fig. 1.102) of the Upper Gondwana is listed:
1. Pteridophytes:
(i) Lycopodiales : Lycopodites.
(ii) Isoetates : Isoetites.
(iii) Equisetales: Equisetites.
(iv) Filicales : Phlebopteris, Marattiopsis, Gleichenites, Sphenopteris, Osmundites, Cladophlebis, Cyclopteris.
2. Gymnosperms:
(i) Corystospermales: Dicroidium, Pachypteris, Cycadopteris.
(ii) Cycadales : Niissonia, Taeniopteris, Macrotaeniopteris, Pseudoctenis.
(iii) Cycadeoidales : Pterophyllum, Ptilo- phyllum, Bucklandia Weltrichia, Zamites, Podozamites, Otozamites, Williamsonia, Cycadeoidea, Anomo- zamites, Sahnioxylon.
(iv) Caytoniales : Sagenopteris, Caytonia, Caytonanthus.
(v) Pentoxylales : Nipaniophyllum, Carnoconites, Pentoxylon.
(vi) Cordaitales : Neoggerathiopsis, Cardio- carpus, Samaropsis.
(vii) Coniferales : Dadoxylon, Stachyotaxus, Elatochadus, Nipaniostrobus, Sitholeya, Indophyllum, Pagiophyllum, Brachyo- phyllum, Araucarites.
(viii) Ginkgoales : Baiera, Ginkgoites.
(ix) Taxales : Taxaceoxylon, Torreyites, Taxites.
