CORALLIAN BEDS. 



331 



layer of large masses of Thamnastrcca concinna and Isastrcca ex- 

 planaia, bored by the characteristic Lithodo?nus inclusus, and 

 changed not seldom into crystalline limestone, in which the 

 organic structure is no longer visible, here spread over the surface, 

 resting immediately upon a bed of sand, which is itself not far 

 removed in elevation from the Oxford Clay."^ 



The Lower Calcareous Grit is exposed near Conygre Farm, and 

 the Coralline Oolite is quarried near the Union Workhouse, at 

 Calne. I am informed by Mr. W. A. Baily that many of the 

 Echinoderms {Hemicidaris intermedia, etc.) for which this locality is 

 noted were obtained from beds exposed to the east of the church. 



The Corallian rocks occur at Cucklington, east of Wincanton, 

 whence they stretch southwards to Marnhull and Sturminster 

 Newton. The quarries south-west of Todbere show about twelve 

 feet of remarkably false-bedded oolitic limestone (Coralline Oolite) 

 overlaid by rubbly, shelly, and oolitic limestone. (See Fig. 48.) 

 The section furnishes evidence of contemporaneous erosion. 

 Pisolitic beds have been traced by Mr. Bristow in the lower portion 

 of the Corallian series in this neig-hbourhood. 



Fig. 



3. — Section between Todbere and Marnhull, near Sturminster 

 Newton. (Prof. J. F. Blake.) 



c^ 



^S^^a^^ai-tb^^s^-i^' 



m^ 



Corallian Beds. \ I'^l^^l"?!''^^' ''f.'''"^ °° 

 ( I^alse-bedded oolites. 



The Corallian Beds are well shown near Weymouth (Weymouth 

 sands and grit), in the cliffs extending from the Nothe to Sandsfoot 

 Castle ; and again to the north, east and west of Osmington, having 

 a thickness of about 200 feet. The various divisions originally 

 described by Sedgwick,- and later on by Buckland and De la Beche,^ 

 have been worked out in great detail by Prof. Blake and Mr. 

 Hudleston.^ The beds are divided as follows (the letters refer 

 to the grouping on p. 327) : — 



/S. Upper Coral Rag and Abbotsbury Ironstone. The former seen 

 near Osmington, and the latter at Abbotsbury. 

 E. F. -| 7. Sandsfoot Grits, 25 feet. Ferruginous fucoidal grits, seen at 

 I Sandsfoot Castle, Linton tlill, etc. 



^(3. Sandsfoot Clay, 40 feet. Ostrca dcltoidca, etc. 



1 Q. J. xxxiii. 28S. 

 ^ Ann. Phil. xi. 339. 



3 T. G. S. (2), iv. I. 

 * Q. J. xxxiii. 262. 



