230 



NUMMULITIC FORMATIONS IN EUEOPE, ETC. [Ch. XVI 



acteristic of those tertiary sti'ata ^vllicll I Lave called Middle Eocene. In 

 very few instances at least do certain species diverge from this narrow- 

 limit, whether into incumbent or subjacent tertiary formations^ it being 

 rather doubtful whether more than one of them, JVummuUtes intermedia^ 

 also a Middle Eocene fossil, ascends so high as the Miocene formation, or 

 whethei' any of them descend to the level of the London clay. Certainly 

 they have never been traced so low down as the marine beds, coeval 

 with the Plastic clay or Lignite, in any country of which the geology has 

 been well worked out. This conclusion is a very unexpected result of 

 recent inquiry, since for many years it was a matter of controversy 

 whether the nummulitic rocks of the Alps and Pyrenees ought not to be 

 regarded as cretaceous rather than Eocene. The late M. Alex. Brongniart 

 first declared the specific identity of many shells of the marine strata near 

 Paris, and those of the nummulitic formation of Switzerland, although he 

 obtained these last from the summit of the Diablerets, one of the loftiest 

 of the Swiss Alps, which rises more than 10,000 feet above the level of 

 the sea. 



The nummulitic limestone of the Alps is often of great thickness, and 

 is immediately covered by another series of strata of dark-colored slates, 

 marls, and fucoidal sandstones, to the whole of which the provincial name 

 of " flysch" has been given in parts of Switzerland. The researches of 

 Sir Roderick Murchison in the Alps in 1847 have shown that all these 

 tertiary strata enter into the disturbed and loftiest portions of the Alpine 

 chain, to the upheaval of which they enable us therefore to assign a com- 

 paratively modern date. 



The nummulitic formation, with its characteristic fossils, plays a far more 

 conspicuous part than any other tertiaiy group in the solid framework of 

 the earth's crust, whether in Europe, Asia, or Africa, It often attains a 

 thickness of many thousand feet, and extends from the Alps to the Car- 

 pathians, and is in full force in the north of Africa, as, for example, in 

 Algeria and Morocco. It has also been traced from Egypt, v/hero it was 

 largely quarried of old for the building of the Pyramids, into Asia Minor, 

 and across Persia by Bagdad to the mouths of the Indus. It occurs not only 

 in Cutch, but in the mountain ranges which separate Scinde from Persia, and 

 which form the passes leading to Caboul ; and it has been followed still far- 

 ther eastward into India, as far as eastern Bengal and the frontiers of China„ 



Fig. 242, 



JVummuUtes Puschi, D'Archiac. Peyrehoradc, Pyrenees. 



«, External surface of one of the nummulites, of which longitudinal sections are seen in the 



limestone. 

 Z>. Transverse section of same. 



