Lamarck, the Founder of Evolution: His Life and Work

by A. S. Packard

He then distinguishes between granitic or crystalline mountains, and those composed of stratified rocks and volcanic mountains.

The erosive action of rivers is thus discussed; they tend first, he says, to fill up the ocean basins, and second, to make the surface of the land broken and mountainous, by excavating and furrowing the plains.

Our author did not at all understand the causes of the inclination or tilting up of strata. Little close observation or field work had yet been done, and the rocks about Paris are but slightly if at all disturbed. He attributes the dipping down of strata to the inclination of the shores of the sea, though he adds that nevertheless it is often due to local subsidences. And then he remarks that “indeed in many mountains, and especially in the Pyrenees, in the very centre of these mountains, we observe that the strata are for the most part either vertical or so inclined that they more or less approach this direction.”

“But,” he asks, “should we conclude from this that there has necessarily occurred a universal catastrophe, a general overturning? This assumption, so convenient for those naturalists who would explain all the facts of this kind without taking the trouble to observe and study the course which nature follows, is not at all necessary here; for it is easy to conceive that the inclined direction of the beds in the mountains may have been produced by other causes, and especially by causes more natural and less hypothetical than a general overturning of strata.”

While streams of fresh water tend to fill up and destroy the ocean basins, he also insists that the movements of the sea, such as the tides, currents, storms, submarine volcanoes, etc., on the contrary, tend to unceasingly excavate and reëstablish these basins. Of course we now know that tides and currents have no effect in the ocean depths, though their scouring effects near shore in shallow waters have locally had a marked effect in changing the relations of land and sea. Lamarck went so far as to insist that the ocean basin owes its existence and its preservation to the scouring action of the tides and currents.

The earth’s interior was, in Lamarck’s opinion, solid, formed of quartzose and silicious rocks, and its centre of gravity did not coincide with its geographical centre, or what he calls the centre de forme. He imagined also that the ocean revolved around the globe from east to west, and that this movement, by its continuity, displaced the ocean basin and made it pass successively over all the surface of the earth.

Then, in the third chapter, he asks if the basin of the sea has always been where we now actually see it, and whether we find proofs of the sojourn of the sea in the place where it is now absent; if so, what are the causes of these changes. He reiterates his strange idea of a general movement of the ocean from east to west, at the rate of at least three leagues in twenty-four hours and due to the moon’s influence. And here Lamarck, in spite of his uniformitarian principles, is strongly cataclysmic. What he seems to have in mind is the great equatorial current between Africa and the West Indies. To this perpetual movement of the waters of the Atlantic Ocean he ventures to attribute the excavation of the Gulf of Mexico, and presumes that at the end of ages it will break through the Isthmus of Panama, and transform America into two great islands or two small continents. Not understanding that the islands are either the result of upheaval, or outliers of continents, due to subsidence, Lamarck supposed that his westward flow of the ocean, due to the moon’s attraction, eroded the eastern shores of America, and the currents thus formed “in their efforts to move westward, arrested by America and by the eastern coasts of China, were in great part diverted towards the South Pole, and seeking to break through a passage across the ancient continent have, a long time since, reduced the portion of this continent which united New Holland to Asia into an archipelago which comprises the Molucca, Philippine, and Mariana Islands.” The West Indies and Windward Islands were formed by the same means, and the sea not breaking through the Isthmus of Panama was turned southward, and the action of its currents resulted in detaching the island of Tierra del Fuego from South America. In like manner New Zealand was separated from New Holland, Madagascar from Africa, and Ceylon from India.

He then refers to other “displacements of the ocean basin,” to the shallowing of the Straits of Sunda, of the Baltic Sea, the ancient subsidence of the coast of Holland and Zealand, and states that Sweden offers all the appearance of having recently emerged from the sea, while the Caspian Sea, formerly much larger than at present, was once in communication with the Black Sea, and that some day the Straits of Sunda and the Straits of Dover will be dry land, so that the union of England and France will be formed anew.

Strangely enough, with these facts known to him, Lamarck did not see that such changes were due to changes of level of the land rather than to their being abandoned or invaded by the sea, but explained these by his bizarre hypothesis of westward-flowing currents due to the moon’s action; though it should be in all fairness stated that down to recent times there have been those who believed that it is the sea and not the land which has changed its level.

This idea, that the sea and not the land has changed its level, was generally held at the time Lamarck wrote, though Strabo had made the shrewd observation that it was the land which moved. The Greek geographer threw aside the notion of some of his contemporaries, and with wonderful prevision, considering the time he wrote and the limited observations he could make, claimed that it is not the sea which has risen or fallen, but the land itself which is sometimes raised up and sometimes depressed, while the sea-bottom may also be elevated or sunk down. He refers to such facts as deluges, earthquakes, and volcanic eruptions, and sudden swellings of the land beneath the sea.