234 SEE— FURTHER RESEARCHES ON [April 24, 



111 his account of the Miocene (" Text-book of Geology," p. 

 1 261, edition of 1903), Geikie says: 



" The Gulf of Gascony then swept inland over the wide plains of the 

 Garonne, perhaps even connecting the Atlantic with the Mediterranean by a 

 strait running along the northern flank of the Pyrenees. The sea washed 

 the northern base of the now uplifted Alps, sending, as in Oligocene time, 

 a long arm into the valley of the Rhine as far as the site of Mainz, which 

 then properly stood at the upper end, the valley draining southward instead 

 of northward. The gradual conversion of salt into brackish and fresh w^ater 

 at the head of this inlet took place in Miocene time. From the Miocene 

 firth to the Rhine, a sea-strait ran eastwards, between the base of the Alps 

 and the line of the Danube, filling up the broad basin of Vienna, sending 

 thence an arm northwards through Moravia, and spreading far and wide 

 among the islands of southeastern Europe, over the regions where now the 

 Black Sea and Caspian basins remain as the last relics of this Tertiary 

 extension of the ocean across southern Europe. The Mediterranean also 

 still presented a far larger area than it now possesses, for it covered much 

 of the present lowlands and foot-hills along its northern border, and some 

 of its important islands had not yet appeared or had not acquired their 

 present dimensions." 



On pages 1371-2 of Geikie's " Geology," we find the following 

 interesting passages : 



"Alpine Type of Mountain Structure. — It is along a great mountain 

 chain like the Alps that the most colossal crumplings of the terrestrial crust 

 are to be seen. In approaching such a chain, one or more minor ridges may 

 be observed running on the whole parallel with it, as the heights of the 

 Jura flank the north side of the Alps, and the sub-Himalayan hills follow 

 the southern base of the Himalayas. On the outer side of these ridges, the 

 strata may be flat or gently inclined. At first they undulate in broad gentle 

 folds; but traced towards the mountains these folds become sharper and 

 closer, their shorter sides fronting the plains, their longer slopes dipping in 

 the opposite direction. This inward dip is often traceable along the flanks 

 of the main chain of mountains, younger rocks seeming to underlie others 

 of much older date. Along the north front of the Alps, for instance, the 

 red molasse is overlain by Eocene and older formations. The inversions 

 and disruptions increase in magnitude till they reach such colossal dimen- 

 sions as those of the Gliirnisch, where pre-Camhrian schists, and Triassic, 

 Jurassic, and Cretaceous rocks have been driven for miles over the Eocene 

 and Oligocene flysch (pp. 677, 693). In such vast crumplings and thrusts 

 it may happen that portions of older strata are caught in the folds of later 

 formations, and some care may be required to discriminate the enclosure 

 from the rocks of which it appears to form an integral and original part. 

 Some of the recorded examples of fossils of an older zone occurring by 

 themselves in a much younger group of plicated rocks may be thus ac- 

 counted for. 



