PLANT-BEAKINO SERIES OE INDIA. 529 



parallel and straight lines, precisely similar to the scoring, furrow- 

 ing, and polishing which rocks carried down by glaciers and 

 ground-ice are so well known to exhibit. And, further, the hard 

 Yindhyan limestone on which this Talchir boulder-bed was laid, 

 was also found to be scored in long parallel lines wherever the 

 upper surface was freshly exposed by the recent removal of the 

 overlying rocks " *. One of the exhumed boulders is now in the 

 Geological Museum of Calcutta ; and I think that an inspection of 

 it would convince the most sceptical of its glacial character. 



]STo similar bed has been described in Australia, where the beds 

 underlying the coal are of marine origin ; but the Karoo formation 

 of South Africa, which resembles the Indian Damuda series in con- 

 taining Glossojpteris and Phyllotheca, has at its base a bed termed the 

 •''Claystone Porphyry" by Bain f, the "Trap Breccia" by WyleyJ, 

 the characters of which evidently closely resemble those of the 

 Talchir " boulder-bed." This resemblance has already been pointed 

 out by Mr. Griesbach § ; but he has fallen into the error of confound- 

 ing the Talchir boulder- bed with one that occurs at the base of the 

 Trichinopoly (Bajmahal) plant-beds, which differs from the former in 

 lithological characters, and is probably an ordinary coast-conglome- 

 rate. The Karoo boulder-bed, according to Dr. Sutherland j|, is not, 

 as supposed by its earlier describers, a volcanic breccia^, but affords 

 distinct evidence of its glacial origin. He describes it as consisting 

 of a greyish blue argillaceous matrix, containing fragments of 

 granite, gneiss, <fec. from the dimensions of sand-grains up to 

 blocks measuring 5 or 6 feet across. They are smoothed, as if they 

 had been subject to attrition in a muddy sediment, but not rounded 

 like sea-worn boulders. The matrix is compact and tenacious ; it 

 has a rude disposition towards stratification, the general appearance 

 being that of a clay which has been deposited by water and after- 

 wards metamorphosed. In some places it is ripple-marked. In 

 Natal the bed rests on Old Silurian Sandstones, which in many 

 cases are deeply grooved and striated. The thickness of this bed, 

 as well as its extent, much exceeds that of the Indian " boulder- 

 bed," since it is as much as 800, sometimes 1200, feet thick ; and 

 it everywhere underlies the Karoo formation, which appears to 

 cover all the interior of South Africa. I defer the discussion of the 

 question whether these two beds are coeval, until I shall have noticed 

 the palseontological evidence of the higher beds of the series. 



The succession given by Mr. Wyley ** is as follows (omitting his 



* Mem. G. S. I. vol. ix. art. 2, p. 30. 



t Trans. Geol. Soc. ser. ii. vol. vii. p. 185. 



\ Quart. Journ. Geol. Soc. vol. xxiii. p. 172. § Loo. cit. p. 60. 



|| Quart. Journ. Geol. Soc. vol. xxvi. p. 514. 



^| It is a curious coincidence that Mr. King, in describing the Talchir boulder- 

 bed near Kamaram, in the Nizam's territory, south of the Godavery, has fallen 

 into what appears to be a similar error. He speaks of the matrix as volcanic 

 muds and ashes, but does not adduce any corroborative evidence of volcanic 

 action during the Talchir period ; and in common with my brother, who has 

 had a very extensive experience of these rocks, I cannot but think it probable 

 that Mr. King has mistaken its lithological character. 



** Quart. Journ. Geol. Soc. vol. xxiii. p. 172. 



2n2 



