BRITISH ASSOCIATION MEETING. 



441 



This cavern was uiuety feet long;, and extended in a direction from nortli- 

 nortli-east to south-south-west, or very nearly that of the dip of the limestone- 

 beds. It commenced about eight feet below'^the top of the cliff, and contmued 

 to its base, so that it is about fifty-two feet high ; indeed its height exceeds 

 this, as the bottom has not been reached. At the top it is about two feet 



Lign. 2.— Vertical transverse section, on the scale of 1-20 inch to the foot, of a Cavern dis- 

 covered at Oreston, near Plymouth, in the winter of 1858-9. 



a, c, d, b, Roof of Cavern, composed of large angular masses of limestone. 



c, e,f, d, "Gravel" of the workmen, i. e., angular Umestone, with a comparatively small 



amount of sand, the whole imcemented. 

 e, g, h,f. Angular limestone, sand, and tough dark clay with bones. 



/, h, k, "CaUis" of the workmen, r. e., a nearly vertical dyke of stalactite, with masses of 



limestone-breccia, the whole containing bones. 

 g, I, m, k Tough dark clay without traces of bones. 



wide, gradually increasing downwards, and reaching a width of ten feet at its 

 bottom. The first or upper eight feet were occupied with what the workmen 

 called " gravel," which consisted of angular portions of the adjacent lunestone, 

 mixed with a comparatively small amount of sand. The lunestone debris 

 varied in dimensions from fragments of the size of hazel-nuts to pieces ten 

 pounds in weight. This accumulation was entirely free from stalagmite, and 

 was in no part cemented. No traces of fossils were found in it. The next 

 thirty-two feet in depth were occupied with similar materials to those just men- 

 tioned (the sand being somewhat more abundant), with the addition of a 

 considerable quantity of tough, dark, unctuous clay. 



