Heroes of science

by P. Martin Duncan

Smith had seen layers of limestone crowded with shells succeeded by others containing corals. He found ammonites and oysters in some, and insect remains in others, and his speculations assumed the curious phase of the sentences just noticed. But he soon became aware that accident had much to do with the presence of certain organic remains in strata, and that, whilst some fossils, like corals, once lived where they are now preserved in strata, others were carried there as the deposit collected.

A manuscript, dated December 2, 1796, Dunkerton, Swan Inn, headed “Strata in general, and their position,” and evidently intended for publication, commences thus:—

“The strata being found as regular on one side of a rivulet, river, deep valley or channel as on the other, over an extent of many miles, when proper allowance is made for the inclination, and for the variation of the surface, is it not reasonable to suppose that the same strata may be found as regular on one side of the sea or ocean as on opposite sides of a deep valley upon land, and if so, and the continuation of the strata is general, what is their general direction or drift? Is it in straight lines from pole to pole, or in curved lines surrounding the globe regularly inclined to the east?”

After hinting at a general cause for such an assumed regularity, he adds, “But all theories are best built on practical rules, which will enable any one to make such observations for himself as must carry conviction along with them; for a work so novel as this must expect to find some who will hardly believe what is plain to be seen; for all men do not see alike, nor can patiently trudge through the dirt to search for truth among the stubborn rocks where nature has best displayed her.... Shall, therefore, describe a number of quarries, cliffs, etc., at a great distance, etc. See Book——”

In what seems to be the continuation of this paper, we see the predominant desire of the author to establish the certainty and generality of the inclination of strata, which he had proved on a limited scale near Bath.

“If the strata lay horizontal, every part of the sea-shore would present the same beds at the water edge instead of that wonderful variety which is found on the coast and banks of every river and rivulet in the kingdom, especially those that run in an east and west direction, or nearly so. In such situations the young mineralogist may soon be convinced of that wonderful regularity which nature has adopted, especially if the shores are rocky; he will there find that, independent of partial and local dips which appear in different quarries of the same stone, the outlines, or top and bottom layers of each complete stratum or class of stones or earth, considered as a mass, have a general tendency towards the eastern horizon.”

By the term “dip” is meant the inclination that strata make with the horizon. Mr. W. Smith constantly brought forward his well worked out fact that the strata of England dip from west to east more or less. The oldest strata come to the surface in Wales and the lake districts, and because they were upheaved the newer strata were tilted and curved, and the slope is to the east.

In February, 1798, we find as part of the introduction to this contemplated work, an interesting notice of some of the steps by which the author was conducted to his general conclusions.

“It will be readily admitted by all classes of men, from the most accurate observers of nature to the simplest peasant, that there is some degree of regularity in the strata from whence our building materials are generally collected. Masons, miners, and quarrymen can identify particular beds of stone dug many miles apart; indeed, every cliff and quarry presents a true section of a great many beds of stone, which may be found of the same quality and in the same position in all or most of the neighbouring cliffs and quarries. And this regularity is nowhere more conspicuous than in the lias quarries of Somersetshire, from whence these observations first took their rise, about seven years since.

“For the stratification of stone struck me, who had not been accustomed to such appearances, as something very uncommon, and till I had learned the technical terms of the strata, and made a subterraneous journey or two, I could not conceive a clear idea of what seemed so familiar to the colliers; but when these difficulties were surmounted, and an intelligent bailiff accompanied me, I was much pleased with my peregrinations below, and soon learnt enough of the order of the strata to describe on a plan the manner of working the coal in the lands I was then surveying.