Scrope had put Werner's notions to the surest test—the evidence of nature—and found them to be ‘idols of the cave;’ so that in 1828 he published the results of his studies in a book entitled ‘Considerations on Volcanos.’ It is full of accurate observations, careful inductions, and suggestive inferences; it enunciates emphatically the doctrine afterwards developed by Lyell and called ‘Uniformitarian,’ but as it was necessarily controversial, was much in advance of its age, and had ventured into a cosmological speculation, it did not meet with a generally favourable reception. The book was rewritten, enlarged, and published under the title ‘Volcanos’ in 1862. But Scrope's ‘Geology and Extinct Volcanos of Central France,’ published in 1826, produced a stronger impression and established the author's reputation as an accurate observer and sound reasoner. A second and revised edition appeared in 1858, and this is still carefully read by every geologist who visits Auvergne. Lyell, who reviewed the first edition in the ‘Quarterly Review,’ xxxvi. 437, justly called it the most able work which had appeared since Playfair's ‘Illustrations of the Huttonian Theory.’ In the same year (1826) Scrope was elected F.R.S.
He was also much in advance of his contemporaries in recognising the action of rivers in the formation of valleys, and was the author (among other contributions to the subject) of an important paper on the Meuse, Moselle, and other rivers (Proc. Geol. Soc. i. 170). His views were practically identical with those of Lyell, whom at this time he might be said, as slightly the senior in geological work, to lead rather than to follow; and when Lyell's ‘Principles of Geology’ appeared in 1827, the book was reviewed by Scrope (Quart. Rev. xlii. 411, liii. 406). He expressed agreement with the author on almost all points, except that he thought Lyell was going rather too far in maintaining that geological change in all past time had been not only similar to, but also in all respects uniform with, what could now be witnessed, and he was more ready than his friend to admit the possibility of a progressive development of species. Some geologists would maintain that Scrope's divergences from the author of the ‘Principles’ indicated a yet clearer perception of the earth's history. In short, it may be said that if Scrope had continued to devote himself wholly to geology, he would have probably surpassed all competitors.
But he also felt a keen interest in politics, in which his brother, afterwards Lord Sydenham, was taking an active part, and his energies were gradually diverted into another channel. Having settled down at Castle Combe, the family seat of the Scropes in Wiltshire, he had been impressed, especially from his experience as a magistrate, with the hardships of the agricultural labourer's life, and he threw himself heartily into the political struggle which was then in progress. In 1833, after the passing of the first reform bill, he was returned to parliament as member for Stroud (having unsuccessfully contested the seat in 1832) and represented the borough till 1868. Here he was an energetic advocate of free trade and various social reforms, especially that of the poor law. But these reforms were urged by his pen, for he was a silent member. His pamphlets, both before and after his entry into parliament, were very numerous. Seventeen stand under his name in the British Museum catalogue, but it is believed that seventy would be nearer the truth, for Scrope's fertility in this respect got him, in the House of Commons, the sobriquet of ‘Pamphlet Scrope.’ In 1833 he published a small volume on ‘The Principles of Political Economy’ (2nd edit. 1874) and another (in 1872) on ‘Friendly Societies.’ He also wrote a life of his brother, Lord Sydenham (1843).
Still geology was not deserted, for in 1856 and again in 1859 the ‘elevation theory’ of craters advocated by Humboldt, Von Buch, and other continental geologists brought Scrope back into the field. This theory, though mortally wounded by himself and Lyell, showed signs of life until his two papers (Quart. Journ. Geol. Soc. xii. 326, xv. 505) extinguished it. Auvergne was again studied by him in 1857, while preparing the revised and enlarged edition of his work on Central France, which appeared in 1858. Nor must a very important and suggestive paper be forgotten, which attributed the foliation of crystalline rocks to differential movements of the materials while the mass was still in an imperfectly solid condition (Geologist, 1858, p. 361).
In 1867 Scrope received the Wollaston medal from the Geological Society, and on his retirement from parliament in the following year geology again obtained a larger share of attention. He lived in retirement during the later years of his life, but his interest in the science was unabated; and when he could no longer travel, he aided younger men less wealthy than himself to continue the study of volcanic districts. Though for some time he suffered from failure of sight, like his friend Lyell, and from some of the usual infirmities of age, he could still
