THE POPULAR SCIENCE MONTHLY.
|RECENT OCEANIC CAUSEWAYS.|
By M. E. BLANCHARD, of the Institute of France.
THE object of this 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 passage between the two continents in the present geological period. But the assertion of the former existence of such a communication 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 Labrador 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. Subsidences 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 Europe 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 anemones, Cruciferæ, violets, and a number of species of Stellaria of the pink family. The astragalus of the Alps thrives in Canada. Among the Rosaceæ we find a series of species of northern and Alpine Europe which occur also in North America—Spiræas, Potentillas and others. Numerous saxifrages, epilobiums, and honeysuckles are common, especially the famous Linnæa borealis. Heaths of several kinds, the rhododendron of Lapland, and primroses, have likewise found their way to America. The families of the scrophularias, the labiates, the borages, and the gentians are al-
- Anemone gratius, A. narcissiflora, and A. hepatica.
- Cardamine bellidiflora, Arabis petræa, and Draba lucana.