280 A Geological Sketch of the Valley of the Kennet. 



those remote ages was probably as common in the forests of 

 this country as the modern elephant is in Central Africa, is well 

 known to have been a characteristic inhabitant of high latitudes. 

 How the hippopotamus —a creature which is now met with only in 

 rivers warmed by a tropical sun, contrived to live in a climate con- 

 genial to mammoths and rein-deer, and in rivers which were 

 probably sometimes laden with ice-floes, is a question not easily 

 solved. But the fact itself, that those animals did co-exist here 

 during the drift period, cannot be disputed ; for theii bones have 

 not only been found embedded in the same gravel, but lying side 

 by side in many limestone caverns, where hyenas and other ravenous 

 beasts were wont to devour their prey. In course of time the 

 mighty river which deposited the low level gravel seems to have 

 shrunk rapidly, if not suddenly, to its present bed. Perhaps its 

 supplies were abruptly cut off by the great convulsion which rent 

 England from the mainland, and thenceforth the attenuated stream 

 precipitated alluvium instead of gravel, spreading widely over the 

 valley a layer of mud or sand whenever it overflowed its banks. 

 A dense jungle soon sprung up in the swampy parts, and the drainage 

 became choked to a great extent between Hungerford and Reading. 

 The result is a bed of peat from two to twelve feet deep, from 

 a quarter of a mile to half a mile in breadth, and about sixteen 

 miles in length, interstratified sometimes hy seams of clay and 

 mud, and covered with one or two feet of alluvium. Remains of 

 the oak, willow, alder, fir, hazel, and birch, are found in the peat ; 

 but the bulk of it seems to have been formed not so much by trees 

 and brushwood as by a plant commonlj'^ called bog-moss, (sphagnum 

 palustre) and other kindred plants. Dr. Buckland tells us that it is 

 much intermixed with minute crystals of selenite and asmall quantity 

 of carbonate of lime.^ The economical value of the peat has much 

 lessened of late years, though the value of it is still considerable. 

 At one time it was sold extensively for fuel. It is now chiefly 

 sold in the form of ashes ^ at 2|d. a bushel, as a fertilizer for green 

 crops. One of the most productive pits is at Speen, where £210 

 ' Trans. Geol. Society, 2nd series, vol. ii. 

 • Those ashes were analyzed by Sir H. Davy, and found to be composed of 



