Cavern in Sunderland. 



105 



At A and B, the rock is but slightly removed from its original 

 position ; but in the space between these points, the slate appears to 

 have been worn away so as to cause the whole conglomerate stratum, 

 which is from 50 to 60 feet thick, and consequently of immense 

 weight, to fall down, producing the fissure a, and the cavern b. The 

 fissure is nine feet wide at the 'top, and open to d, 40 feet ; below which 

 it is filled with rubbish. The cavern is wider than this in some parts, 

 though very irregular in this respect. Its bottom also is rendered 

 quite uneven by the large masses of rock that have tumbled down. 

 In the deepest spot, (56 feet,) the rocks are separated to the surface, 

 so as to let in the light from above. The whole length of the cavern 

 is 148 feet. Its general direction is nearly east and west. But to- 

 wards its eastern part it turns almost at right angles to the left, in 

 consequence of the rock A, having been broken in a north and south 

 direction from the mass of the mountain. 



Some who visit this spot are disposed to call in the aid of a convul- 

 sion like an earthquake to explain the huge fractures there exhibited. 

 But after seeing so many other marks of the powerful action of at- 

 mospheric and aqueous agents on this mountain, I cannot but believe 

 the cause I have assigned to be sufficient. The place is well worth 

 visiting by all who have not examined other caverns and fissures 

 extensively. 



On the opposite side of Mount Toby, a little south of the cascade 

 that has been described, one or two other caves occur, more irregu- 

 lar but less extensive than this. They have been produced by the 

 enormous masses of the mountain that have been here mixed pell- 

 mell together. 



Caverns in Berkshire. 



These all occur in limestone ; and are so similar, that it is hardly 

 necessary to describe them separately. Two exist in the south part of 

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