iFurfycr i&otes on erttrestoell 33ale &ttar¥g, 



By Tohn Ward.' 





|T is several years since I was in Tideswell Dale Quarry ; 

 but I remember it well, for it was then that I first 

 made my acquaintance with " Spheroids." They 

 particularly attracted my attention, for I almost at 

 once began to doubt the usual theory of their origin — as due to 

 the cooling and contraction of the rock in the process of 

 solidification. Since then the occasional examination of the 

 phenomena elsewhere, in the same rock (Toadstone) of the 

 district, has only tended to strengthen my conviction. 



I do not dispute the possibility of structures known under this 

 name in igneous rocks, to arise from such causes as the theory 

 implies. I have a photograph of greenstone at Cader Idris, which 

 at the first glance is remarkably like the rock containing spheroids, 

 at Tideswell. But upon closer inspection wide differences will be 

 noticed between them. The spheroids of Tideswell consist of 

 rounded cores (A, Fig. 5), each enveloped in a series of zones 

 or shells (BB) (giving the appearance of a stony onion to the 

 structure) ; sometimes there are as many as 14 or 16 of these 

 zones, and the diameters of these spheroids range from two or 

 three to nine inches. At Cader the " nodules " are much more 

 irregular in shape, and there are no traces of such shells, in 



*Mr. Fletcher also supplies us with the following further notes on Tideswell 

 Dale Quarry and igneous rocks, by Mr. John Ward, which were written to 

 him in the form of a letter commenting on his own notes. — Ed. 



