208 A LUMP OF CHALK AND ITS LESSONS. 



we go lower down in the rock series, we shall find the white 

 character of- the chalk has completely disappeared when 

 we reach the underlying blue "gault" of Folkestone, which 

 implies the existence of currents or rivers largely charged 

 with mud. Still further back, we have the fresh-water clays 

 and sandstones of the Weald of Kent and Sussex ; and 

 we thus learn that at that period southern England was in 

 the condition of a large delta, after which there was a 

 gradual subsidence, culminating in the mare clausum of the 

 period of the white chalk. Then, again, we have seen 

 how the " architectural style " of a rock, as exemplified by 

 its fossils, is the one all-important point connected with 

 it; and the alteration of the English chalk into the 

 cretaceous sandstones of Saxony ought to have prepared 

 us for more extensive modifications of these rocks as we 

 proceed to regions still more remote from where they are 

 typically developed. If, then, we tuni to a geological map 

 of Europe, we shall find a large area of its southern half 

 coloured in, as being formed of cretaceous rocks that is, 

 rocks equivalent in point of age to the white chalk. The 

 description, or still better, an actual examination of these 

 rocks will show, however, that they have but little in 

 common with the white chalk. They consist, indeed, of 

 hard, compact, and often dark-coloured limestones, con- 

 taining many fossils identical with those of our own chalk, 

 together with certain others of different types ; thus 

 showing that we have entered an area where the conditions 

 of life were somewhat different from those obtaining in 

 the mare clausum of the white chalk. From the centre 

 and south of France these cretaceous limestones may be 

 traced across the Pyrenees into Spain, and so into North 

 Africa, while eastwards they extend across the Alps into 

 Switzerland, Italy, Bulgaria, Koumania, and thence along 

 the Mediterranean basin into Asia. That these rocks 

 stretch far into the heart of Asia is now well known, and 

 since rocks of somewhat similar type containing well- 

 known European cretaceous fossils are found in the inner 

 Himalayas, it seems highly probable that this southern 

 cretaceous sea connected the Mediterranean with the Bay 

 of Bengal. Whereas similar cretaceous fossils occur on 



