50 Mr. Henry Walker's Lecture: 



land-surface arose above the icy waters, and began to be 

 sculptured into water- sheds and river-basins, down to 

 these latest days, such valleys have served as great hiding- 

 places and storehouses for the varied drift of the landscapes 

 which drain into them. 



From the deposits of our old rivers we learn the kind 

 of denizens which dwelt on the adjacent snow-clad hills 

 and plains, or among the forests, jungles, swamps, and 

 prairies of mammoth-haunted England. During long and 

 eventful ages, marked by great changes in the climate, 

 zoology, and physical geography of our land, the rivers 

 have entombed and treasured up the drift of the wide 

 terrestrial area around them. They have thus preserved, 

 until future ages, many a relic which would have been 

 left to decay or sudden destruction on the land, had it not 

 been swept by floods to the care and custody of the valley. 



In this way the rivers were acting as the chroniclers of 

 physical England long ere human historians appeared. In 

 ages long antecedent to the annals of man, the Thames 

 was storing its valley with that wondrous archaeology of 

 Nature which we to-day in weekly rambles are privileged 

 to explore. Through an incalculable long period, marked 

 by changes in the climate and the separation of Britain 

 from the Continent and by the dying out or dispersal of 

 old-world forms of life, the Thames and its tributaries, 

 from the Cotswolds downwards, have been pouring their 

 waters down to the great receiving-drain of the lower 

 Thames Valley. And so to-day we learn from these invo- 

 luntary chroniclers what strange inhabitants dwelt in this 

 Essex country of ours, fellow-denizens with man, and yet 

 of whom man himself has left no record. 



These river graves at Ilford and Grays Thurrock are to 

 the Londoner what the limestone caves of Victoria, Kirk- 

 dale, and Torquay are to the inhabitants of Yorkshire and 

 Devonshire. They are a natural museum of the mammoth 

 and rhinoceros period in England. In the valley of the 

 lower Thames, the rocks are not of the limestone texture 

 which elsewhere has been gradually hollowed out into 

 caverns and fissures to serve as sepulchres for our old 



