88 



THE GEOLOCtIST. 



tain limestone, as we continue our researches higher up m the beds 

 we find their remains becoming more scanty, until at the top they are 

 exceedingly rare. One bed is rich in zoophytes, another m gomatites, 

 whilst another is composed of the broken fragments oi Sanguino- 

 laria, and the whole of the beds contain numbers oi Spirifer imlricatus, 

 which connects them like a huge bracket from top to bottom. Some 

 rare geologizing may be had along the lower beds; almost every 

 stroke of the hammer lays open something novel. 



The remarkable fissures which occur in the limestone of Derbyshire 

 have afforded matter of speculation to the curious for centuries ; the 

 most remarkable one is called the Winnats, and is about a mile dis- 

 tant from Castleton. It gives rise to the most sublime scenery, for 

 the fissure is caused by the splitting of a hill in twain, and the steep 

 precipices on either hand for the distance of a mile and a half, resem- 

 ble the ruins of old towers and buttresses, in some places clad with 

 ivy, and tenanted by bats and owls. Another such fissure is at the 

 back of the town, and has been already referred to. In some places 

 the passage at the bottom of this is not above three yards in width, 

 and is much of a character, in other respects, with the Winnats. 

 Much speculation has arisen as to the origin of these rents ; they occur 

 at nearly right angles to the line of strike, and have doubtless been 

 formed in the first instance by the upheaval and desiccation of the 

 rocks, thus :— 



Kg. 2. 



Subsequent to this they have been worn and channelled by at- 

 mospheric and aqueous action. They have been attributed to plutonic 

 agency, bat it needs little geological knowledge to see that the above 

 theory is the true one. Along the lower beds in the Cave Dale there 

 is another good spot or two for the geologist. Here are found 

 numbers of trilobites, some quite entire ; groups of the entomostra- 

 can Ciitherfp, and that rare fossil the Cyclas radialis. One bed seems 

 quite a nest of Fhurorhi/ncus arraatus, although they are very fra- 

 gile and require great care to extract them with the cone entire. 

 Phitouic action has not been absent in the neighbourhood, for at 

 the top of this fissure are beds of greenstone, and an imperfectly 

 columnar basalt, whilst the limestone around seems to be somewhat 

 crystallized by the heat to wliich it has been subjected by the in- 

 trusion. 



Old Mam Tor, the "Shivering Mountain," in geological position 

 lies just abiwe the limestone. The shales which compose it are 

 epcodily decomposed by atmospheric agency, and hence have given 

 rise to the popular name which the mountain bears. The inclination 

 of its beds is E.X.E., and the intensity of their dip about 40°. These 



