OF CONCHOLOGY. 25 



ON THE LAND AND FRESH-WATER MOLLUSCA OF 

 GREENLAND* 



BY OTTO A. L. MORCH, 

 (Of the Royal Museum, Copenhagen.) 



That the distance between Europe and America must have 

 been much smaller formerly than at present, even up to a com- 

 paratively recent period, is rendered highly probable from com- 

 paring several geological facts. 



During the great glacial period, or boulder formation, under 

 which the greatest part of Europe and Siberia were covered by 

 the ocean, a general rising of the land took place, during which 

 most of the older strata down to the chalk were disturbed by the 

 retiring sea. 



The raised land became covered with large woods, composed 

 of firs, alders, lime trees, but not the beech tree, exactly corres- 

 ponding to the forests at present growing in the cooler parts of 

 Russia, as proved by the submarine forests which encircle the 

 coasts of Denmark, Holland, France, England and Ireland. 



The coldness of the climate depended probably on the circum- 

 stance that the Mexican Gulf Stream did not exist at that time, 

 either because it was going over Panama, or the Atlantic Ocean 

 was a closed or nearly a closed gulf. The countries now sur- 

 rounding the German Sea were at that time so far removed from 

 the sea or the gulf stream, that the climate was a continental 

 one, with very severe winters. 



Iceland may have formed a part of this continent, as it appears 

 not very likely that the considerable woods destroyed by man in 

 historical times could be formed on an island emerged from the 

 sea under the present clime. 



The German Sea was perhaps at that period only a gulf, like 



* Our readers will be gratified, doubtless, to learn that Prof. Morch 

 proposes to furnish frequent papers to the Journal. The present article 

 is authoritative as to its conclusions, being based on the type specimens 

 of the various Greenland explorers and authors. — Editor. 



