88 PREHISTORIC E UR OPE. 



Professor Prestwich, after carefully weighing all the evidence, 

 comes to the following conclusions : — The shingle, which forms 

 the basement-bed, may have been introduced by water flowing 

 over the slates, grits, and shales that occur to the westward of 

 Brixham. Owing to the small drainage-area and the impermeable 

 nature of the rocks, this old stream would occasionally become 

 dry ; and at such periods the remains of the mammoth, horse, 

 and ox, which occur in the shingle, might have been brought in 

 at intervals by lions and hyaenas and devoured on the spot — the 

 bones showing evident marks of having been gnawed. At this 

 period in the history of the cave, " the valley of Brixham and 

 its tributaries, which then as now formed the channels of drain- 

 age of the district, must have been from 70 to 80 feet less deep 

 than at present." "After the cave had become choked with 

 shingle," continues Professor Prestwich, " the stream, either from 

 that cause, or from the deepening of the channels outside, kept 

 more in the main valley, and a period of quiet succeeded, during 

 which a first bed of stalagmite was deposited immediately upon 

 the bed of shingle." This is the stalagmite which Mr. Pengelly 

 calls a " stalagmitic ceiling." Ere long it was broken up and the 

 surface of the shingle-bed, upon which it rested, was lowered to 

 the extent of from six to ten feet — effects which may have been 

 produced, according to Professor Prestwich, " either by an 

 irruption of water carrying away part of the shingle, and so 

 undermining the stalagmite, or by the breaking-up of the stal- 

 agmite, and the settling-down of the shingle deeper into the 

 fissures by earthquake -movements." In whatever way the 

 change took place, there can be no doubt that the succeeding 

 accumulation of cave-earth bears witness to very different hydro- 

 graphical conditions.' No shingle-bearing streams now entered 

 the fissures, but the cave was habitually dry. Occasionally, 

 however, it was visited by floods from the main stream of the 

 Brixham valley, which deposited their silt upon the floor, and 

 thus during successive inundations the so-called " cave-earth " 

 gradually accumulated. The breaking up of the first bed of 

 stalagmite, and the lowering of the surface of the shiugle-bed, 



