190 Marsh. 



found all over the world in rocks both of Tertiary and Post- 

 Tertiary age, and there is very considerable difference in 

 the skill with which they have been fashioned, the earlier 

 being roughly chipped or hewn, the later more or less 

 smoothly polished. With the former we find remains of 

 the mammoth, cave bear and woolly rhinoceros, whilst with 

 the latter there are no remains of any of these animals, 

 which had evidently become extinct. During the New 

 Stone Age we have good reasons for supposing that agri- 

 culture was practised, and several animals for the first time 

 domesticated. There can be no doubt from the great differ- 

 ence in the workmanship, and from the gradual transition 

 from the rudest to the most highly polished stone imple- 

 ments, that the two " Stone " Ages covered a very consider- 

 able period of time. 



Most of the material upon which the conclusions con- 

 cerning pre-historic man are based, has been found in the 

 Post- Tertiary deposits, or in chalk and limestone caves. The 

 Post-Tertiary rocks themselves consist of (1) A layer of 

 grey gravel, above which is (2) a layer of red gravel, whilst 

 on the top of this again is (3) a layer of loam. In these 

 deposits are found the remains of the mammoth, woolly 

 rhinoceros, Irish elk and many other extinct animals, be- 

 sides those of the reindeer, hippopotamus, lion and other 

 animals which have since migrated from their old dwelling 

 places, or have otherwise become more restricted in habitat. 



But it is in the caves that the greatest amount of interest 

 centres. These are found in chalk and limestone districts, 

 and have evidently been made by the erosion of running 

 water. They were used during vast periods of time as the 

 lairs of man and of the various kinds of animals whose re- 



