And while the world of thought was thus seething and moving restlessly before the wave of ideas set in motion by these various independent philosophers, another group of causes in another field was rendering smooth the path beforehand for the future champion of the amended evolutionism. Geology on the one hand and astronomy on the other were making men's minds gradually familiar with the conception of slow natural development, as opposed to immediate and miraculous creation.
The rise of geology had been rapid and brilliant. In the last century it had been almost universally believed that fossil organisms were the relics of submerged and destroyed worlds, strange remnants of successive terrible mundane catastrophes. Cuvier himself, who had rendered immense services to geological science by his almost unerring reconstructions of extinct animals, remained a partisan of the old theory of constant cataclysms and fresh creations throughout his whole life; but Lamarck, here as elsewhere the prophet of the modern uniformitarian concept of nature, had already announced his grand idea that the ordinary process of natural laws sufficed to account for all the phenomena of the earth's crust. In England, William Smith, the ingenious land surveyor, riding up and down on his daily task over the face of the country, became convinced by his observations in the first years of the present century that a fixed order of sequence could everywhere be traced among the various superincumbent geological strata. Modern scientific geology takes its rise from the moment of this luminous and luminiferous discovery. With astonishing rapidity the sequence of strata was everywhere noted, and the succession of characteristic fossils mapped out, with the result of showing, however imperfectly at first, that the history of organic life upon the globe had followed a slow and regular course of constant development. Immediately whole schools of eager workers employed themselves in investigating in separate detail the phenomena of these successive stages of unfolding life. Murchison, fresh from the Peninsular campaign, began to study the dawn of organic history in the gloom of the Silurian and Cambrian epochs. A group of less articulate but not less active workers like Buckland and Mantell performed similar services for the carboniferous, the wealden, and the tertiary deposits. Sedgwick endeavoured to co-ordinate the whole range of then known facts into a single wide and comprehensive survey. De La Beche, Phillips, and Agassiz added their share to the great work of reconstruction. Last of all, among those who were contemporary and all but coeval with Charles Darwin himself, Lyell boldly fought out the battle of 'uniformitarianism,' proving, with all the accumulated weight of his encyclopædic and world-wide knowledge, that every known feature of geological development could be traced to the agency of causes now in action, and illustrated by means of slow secular changes still actually taking place on earth before our very eyes.