E. Suess — Paleogeocjraphy of North America. 103 



filled a great part of the fore-depth of the eastern Alps, Car- 

 pathians, and Apennines, and it is very curious that similar 

 beds occur on the external (southern) side of the Alaskan 

 (Aleutides) arch [described fully in " Face of the Earth," IV : 

 376-378]. Your Coloradoan Sea with the posthumous folding 

 of the Laramide Range and the pressure from the Pacific 

 agrees perfectly with European experience. 



Other examples are not so definite. Take the Middle Juras- 

 sic. A transgression of this age appears on Franz Josef land 

 and other islands of that part of the Atlantic, attains the north- 

 ern coast of Russia, forms a broad strip on the west side of 

 the Ural Mountains, attains the Caspian, mixes with Tethys, 

 but lies in transgression beyond the borders of this sea in east- 

 ern Bavaria, and at the same time, with very similar fossils, 

 appears in the Argentinian Andes, spreads farther than the 

 southern borders of Tethys beyond Damascus, lies on Gond- 

 wana beds in German East Africa, also in transgression on old 

 rocks in Khach (East India), as well as in western Australia, 

 southern New Guinea, etc. This same transgression is met 

 with in different parts of northern Siberia as a wide fiat series 

 of beds. It is the Enochkin and JSiaknek of the Alaskan 

 peninsula and your Sundance transgression (Logan Sea). 



In some places the middle Lias has left traces in the regions 

 beyond Tethys, as in Madagascar; Ammonites amaltheas of 

 the Lias has been found beneath this transgression in arctic 

 Siberia (1 believe on the lower Anabar but have no books 

 here), but with these few exceptions the transgression of 

 about Kelloway age everywhere rests on by far older rocks. 



It is the strip along the west or front side of the Urals 

 which connects the Arctic with Tethys, and eminent Russian 

 geologists thought that a syncline was formed in front of the 

 Urals. But curiously enough, transgression also proceeds from 

 Tethys far to the south, and I am inclined to believe that the 

 strip along the west side of the Urals was simply due to the 

 sea entering a river system, let us say of a pre-Jnrassic Volga. 



I do not know enough about the relations of your Logan 

 Sea to the Oregon Jurassics and of these to the Franciscan 

 Jurassic Radiolaria to speak about them and only desire. to 

 point out the necessity of comparison and the difficulties. 

 The evident entrance of fore-depths into the area of the exist- 

 ing continents, as for instance the one in front of the Carpa- 

 thians and Alps extending through the middle of Europe and 

 depositing Jurassic Radiolaria even in the suburbs of Vienna, 

 always has prevented me from acceding to the opinio:!, that 

 only " epi-continental seas" had entered the present conti- 

 nents. In Europe north of the Alps mountain-making ended 

 before the upper Carboniferous or upper Permian, and coin- 



