86 PREHISTORIC EUROPE. 



loosened blocks and fragments. Bnt such will hardly account 

 for all or even for any great proportion of the scattered blocks 

 and thick aggregations of limestone-^M>m that are met with in 

 so many caves. I am inclined to believe that very many of 

 these fragments may have been dislodged by the action of frost, 

 which at some epochs during the Pleistocene Period was cer- 

 tainly more intense in our latitude than it is now. This would 

 account for the more abundant presence of fallen blocks and 

 debris at and near the entrances of caves, for in the deeper 

 recesses the cold would necessarily be less intense, and less 

 capable therefore of rupturing the limestone and detaching 

 angular fragments. If the dislodgment of all these fragments 

 had been due solely to the corrosive action of percolating water 

 or to the vibrations of earthquakes, we should be at a loss to 

 understand why the greatest falls should have so frequently 

 taken place in those portions of the caves that are most acces- 

 sible to the influence of the external atmosphere. 



Eeference has been made to the fact that deposits of gravel, 

 sand, and earth frequently occur in caves, sometimes underlying 

 and not uncommonly intercalated with sheets or pavements of 

 stalagmitic matter. The history of these accumulations often 

 impresses us fully as much as that of the stalagmites themselves 

 with the length of time required for their formation. One or 

 two examples may suffice to show what is meant. The first I 

 shall cite is that of Brixham Cave, which has been carefully 

 explored by a committee of well-known geologists and archae- 

 ologists. 1 This cave occurs on a little hill overlooking the small 

 fishing-town of Brixham, Torbay, and its entrance is about 95 

 feet above high water. The deposits met with consisted of the 

 following accumulations, which are named in descending order: — 



1. Stalagmitic Floor of irregular thickness, varying from a few inches 

 to upwards of one foot. 



2. Breccia, consisting of small angular fragments of limestone, cemented 

 together by carbonate of lime. This deposit filled up the northern entrance 



1 "Report on the Exploration of Brixham Cave, etc.," by Joseph Prestwich, 

 F.R.S., F.G.S., etc. Philosophical Transactions, 1874, p. 471. 



