206 THE BOOK OF NATURE STUDY 



are common, and so are links between marsupials and carnivora, 

 while most of the forms are not to be exactly referred to 

 existing orders, but are ancestral forms or links between them. 

 The vegetation is mainly dicotyledonous, but there is an 

 abundance of palms, and most of the plants are such as live in 

 subtropical latitudes. 



The rocks provide sands and clays for brick making, but 

 little else of economic value is obtained. The landscape is flat 

 or gently undulating, some of the sand beds giving rise to heaths 

 and commons like those about Bagshot, Aldershot, Hampstead, 

 and the New Forest. 



The Oligocene System is found only in the Hampshire Basin, 

 including the Isle of Wight. The rocks are estuarine, fluviomarine, 

 or fresh water in origin, and consist of sands, shelly marls, and 

 ill-consolidated limestones. The common fossils are fresh and 

 brackish water shells, with bones and teeth of land animals. 

 While the invertebrate fossils approach very closely to existing 

 forms, and are sometimes identical with them, the mammals 

 still present wide differences. The vegetation still indicates a 

 climate warmer than Britain of the present, and shows such forms 

 as fan-palms, feather-palms, and cinnamons. 



The Miocene System is not found in Britain. On the 

 continent it indicates a Period of shallow water, lakes, and much 

 earth movement. 



The Pliocene Rocks are found only in Eastern England. They 

 are mainly sands and shell-beds full of fossils. The shells are 

 at first such as live in latitudes a little south of Britain, later 

 they are closely linked with British forms, and in the end they 

 include many arctic types. Few of the shells have become 

 absolutely extinct, though many have left British waters. This 

 indicates a gradual refrigeration in the climate. The mammalia 

 shows a close approach to living types, and a few species which 

 still survive have made their appearance. They include the 

 extinct mastodon and the living horse and hippopotamus. The 

 vegetation differs only in a few respects from that at present 

 living in the same area. The landscape is usually flat and not 

 very interesting, and the economic application of the rocks is 

 almost limited to the marling of fields. 



