44 Geological Conditions of the Chalky 



felspar. Hornblende and felspar (basalt). Compact horn- 

 blende rock. Three other modifications of hornblende, in 

 separate large boulders. Greenstone. Sienite. 



Organic Remains found in the Clay. 



Radiata, — Pentacrinite. 



Annuldta. — Serpula. 



Conchifera. — Gryphae^a dilatata, Gryphae^a incurva, Gry- 

 phae x a arcuata. Avicula. Plagiostoma. Cyclas. Cyrina. 

 Cardita. A'rca. 



Mollusca. — Three species or varieties of ammonite. Be- 

 lemnites. Pleurotoma? 



Pisces. — Vertebras of a species of Squalus. 



CHALK. 



The upper surface of the chalk in this locality appears to 

 have been subjected to violent abrasion and waste, previous to 

 the deposition of the clay upon it> by its broken surface, and 

 the suddenly truncated ends of its strata at their terminations. 



It is impossible te conclude that such heavy and compact 

 bodies, as the large blocks and boulders which are found in 

 the clay above, and are evidently foreign to this locality, could 

 have been rolled along over the surface of the chalk without 

 scooping out, and wasting its surface; or that its surface 

 should be otherwise than we find it, namely, lacerated and 

 broken. 



In support of this breaking up of the chalk strata, previous 

 to the deposition of the clay, I shall adduce one or two facts. 

 At the village of Lamarsh, about four miles from Ballingdon, 

 as we descend the stream of the river Stour, on its southern 

 side, are to be seen a group of large blocks of green sandstone : 

 one, 6 ft. long, and about one ton in weight ; from which I 

 detached a good characteristic specimen. To the transporting 

 cause which brought the large blocks and boulders of granite, 

 gneiss, &c, from their native beds, we may, perhaps, attribute 

 the formation of the mound or hill of large angular flints which 

 is so strikingly displayed at Acton, within three or four miles 

 of Ballingdon : noticed in VIII. 352. And may we not add 

 the formation of the whole of our heterogeneous gravel beds 

 to the same cause ? It is curious and interesting, at least to 

 persons following these pursuits, to observe the outsides of 

 some of the boulders, being highly polished, without doubt 

 by the friction which they must have undergone on their jour- 

 ney hither. This polish is particularly evident on the outsides 

 of the hard limestone boulders found here. 



At a quarry, near the foot of this hill, the chalk is delved to 

 the depth of 37 ft. from its junction with the clay. This gives 



