PRESERVATION n 



frequently comes across the remains of plants and animals that 

 have undergone very little change, and have, as it were, been 

 simply sealed up. The state of a fossil depends on several 

 circumstances, such as the soil, mud, or other medium in which 

 it may happen to be preserved. Again, the newest, or most recent, 

 fossils are generally the least altered. We have fossils of all 

 ages, and in all states of preservation. As examples of fossils 

 very little altered, we may take the case of the wonderful collec- 

 tion of bones discovered by Professor Boyd Dawkins in caves in 

 various parts of Great Britain. The results of many years of 

 research are given in his most interesting book on Cave- Hunting. 

 This enthusiastic explorer and geologist has discovered the remains 

 of a great many animals, some of which are quite extinct, while 

 others are still living in this country. These remains belong to 

 a late period, when lions, tigers, cave-bears, wolves, hyaenas, and 

 reindeer inhabited our country. In some cases the caves were 

 the dens of hyaenas, who brought their prey into caverns in 

 our limestone rocks, to devour them at their leisure ; for the 

 marks of their teeth may yet be seen on the bones. In other 

 cases the bones seem to have been washed into the caves by old 

 streams that have ceased to run ; but in all cases they are 

 fairly fresh, though often stained by iron-rust brought in by 

 water that has dissolved iron out of various rocks for iron is a 

 substance met with almost everywhere in nature. Sometimes 

 they are buried up in a layer of soil, or "cave-earth," and at 

 other times in a layer of stalagmite a deposit of carbonate of 

 lime gradually formed on the floors of caves by the evaporation 

 of water charged with carbonate of lime. 



Air and water are great destroyers of animal and vegetable 

 substances from which life has departed. The autumn leaves 

 that fall by the wayside soon undergo change, and become at last 



