540 THE POPULAR SCIENCE MONTHLY. 



RECENT OCEANIC CAUSEWAYS. 



By M. E. BLANCHAED, of the Institute of Feance. 



e 



THE object of tliis paper is the survey of the most remarkable 

 changes that have taken place in the configuration of the 

 land and the seas. My purpose is to show by an aggregation of 

 proofs that the European and American continents were, to a 

 certain extent, united at an epoch of only moderate geological 

 antiquity. When we consider the extent of the Atlantic Ocean 

 between Europe and America, as measured by the usual routes 

 across it, we reject all thought of there ever having been a pas- 

 sage between the two continents in the present geological period. 

 But the assertion of the former existence of such a communica- 

 tion should cause no surprise, if we regard the arctic regions of 

 both shores of the Atlantic. In fact, if we follow a line drawn 

 from the islands north of Scotland through the Faroe Islands to 

 Iceland, from Iceland to Greenland, and from Greenland to Labra- 

 dor through Davis Strait, which is crowded with islands and 

 islets, we find a chain of lands interrupted only by spaces of sea 

 of small extent, and in some places of no great depth. Subsi- 

 dences of the ground and erosions have caused the isolation of 

 lands which were united in former ages, when living Nature had 

 assumed a character which has not ceased to exist down to our 

 own days. A similar phenomenon produced the separation of 

 England. 



The application of natural history to physical geography and 

 the history of the globe casts a full light upon this matter. The 

 flora and fauna of North America are distinguished from those 

 of Europe by essential traits. This fact contributes in a striking 

 manner to establish the passage of a number of species from Eu- 

 rope to America. The demonstration appears complete when we 

 look at the number and the character of the plants and animals 

 inhabiting both continents. Among these are several anemo- 

 nes,* Crucifer(S;\ violets, and a number of species of Stellaria of 

 the pink family. The astragalus of the Alps thrives in Canada. 

 Among the RosacecB we find a series of species of northern and 

 Alpine Europe which occur also in North America — Spirceas, Po- 

 tentillas and others. Numerous saxifrages, epilobiums, and 

 honeysuckles are common, especially the famous LinncBa horealis. 

 Heaths of several kinds, the rhododendron of Lapland, and prim- 

 roses, have likewise found their way to America. The families of 

 the scrophul arias, the labiates, the borages, and the gentians are al- 



* Anemone grafius, A. narcissijlora, and A. hepatica. 



f Cardamine bellidijlora, Arabis petrcea, aud Draha lucana. 



