Nat., 1792) he made the first careful study of the coal formation in the Cevennes, including its beds of coal, sandstone, and shale.

A.de Jussieu had previously supposed that the immense deposits of coal were due to sudden cataclysms or to one of the great revolutions of the earth during which the seas of the East or West Indies, having been driven as far as into Europe, had deposited on its soil all these exotic plants to be found there, after having torn them up on their way.
But Bruguiere, who is to be reckoned among the early uniformitarians, says that "the capacity for observation is now too well-informed to be contented with such a theory," and he explains the formation of coal deposits in the following essentially modern way: "The stores of coal, although formed of vegetable substances, owe their origin to the sea.

It is when the places where we now find them were covered by its waters that these prodigious masses of vegetable substances were gathered there, and this operation of nature, which astonishes the imagination, far from depending on any extraordinary commotion of the globe, seems, on the contrary, to be only the result of time, of an order of things now existing, and especially that of slow changes" (i, pp.

116, 117).
The proofs he brings forward are the horizontality of the beds, both of coal and deposits between them, the marine shells in the sandstones, the fossil fishes intermingled with the plant remains in the shales; moreover, some of the coal deposits are covered by beds of limestone containing marine shells which lived in the sea at a very great depth.
The alternation of these beds, the great mass of vegetable matter which lived at small distances from the soil which conceals them, and the occurrence of these beds so high up, show that at this time Europe was almost wholly covered by the sea, the summits of the Alps and the Pyrenees being then, as he says, so many small islands in the midst of the ocean.

He also intimates that the climate when these ferns ("bamboo" and "banana") lived was warmer than that of Europe at present.
In this essay, then, we see a great advance in correctness of geological observation and reasoning over any previous writers, while its suggestions were appreciated and adopted by Lamarck.
[79] Hooke had previously, in order to explain the presence of tropical fossil shells in England, indulged in a variety of speculations concerning changes in the position of the axis of the earth's rotation, "a shifting of the earth's centre of gravity analogous to the revolutions of the magnetic pole, etc." (Lyell's _Principles_).