Sir Charles Lyell, 1st Baronet, FRS (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history.

The philosopher William Whewell dubbed this gradualistic view "uniformitarianism" and contrasted it with catastrophism, which had been championed by Georges Cuvier and was better accepted in Europe.

[1] The combination of evidence and eloquence in Principles convinced a wide range of readers of the significance of "deep time" for understanding the earth and environment.

[2] Lyell's scientific contributions included a pioneering explanation of climate change, in which shifting boundaries between oceans and continents could be used to explain long-term variations in temperature and rainfall.

As Darwin wrote in On the Origin of Species, "He who can read Sir Charles Lyell's grand work on the Principles of Geology, which the future historian will recognise as having produced a revolution in natural science, yet does not admit how incomprehensibly vast have been the past periods of time, may at once close this volume.

"[5] Lyell helped to arrange the simultaneous publication in 1858 of papers by Darwin and Alfred Russel Wallace on natural selection, despite his personal religious qualms about the theory.

His family's second country home was in a completely different geological and ecological area: he spent much of his childhood at Bartley Lodge in the New Forest, in Hampshire in southern England.

[7] By 1827, he had abandoned law and embarked on a geological career that would result in fame and the general acceptance of uniformitarianism, a working out of the ideas proposed by James Hutton a few decades earlier.

[15][16] The jawless fish Cephalaspis lyelli, from the Old Red Sandstone of southern Scotland, was named by Louis Agassiz in honour of Lyell.

These span Lyell's long scientific career (1825–1874), and offer an unrivalled insight into personal influences, field observations, thoughts and relationships.

They were acquired in 2019 by the University of Edinburgh's Heritage Collections, thanks to a fundraising campaign, with many generous individual and institutional donors from the UK and overseas.

Highlights include his travels throughout Europe and the United States of America, the drafts of his correspondence with the likes of Charles Darwin, his geological and landscape sketches and his constant gathering of evidence and refinement of his theories.

Lyell rejected Lamarck's idea of organic evolution, proposing instead "Centres of Creation" to explain diversity and territory of species.

He encouraged Darwin to publish, and following the 1859 publication of On the Origin of Species, Lyell finally offered a tepid endorsement of evolution in the tenth edition of Principles.

[6] The systematic, factual description of geological formations of different ages contained in Principles grew so unwieldy, however, that Lyell split it off as the Elements in 1838.

Late in his career, therefore, Lyell produced a condensed version titled Student's Elements of Geology that fulfilled the original purpose.

[7] He was, along with the earlier John Playfair, the major advocate of James Hutton's idea of uniformitarianism, that the earth was shaped entirely by slow-moving forces still in operation today, acting over a very long time.

Criticizing the reliance of his contemporaries on what he argued were ad hoc explanations, Lyell wrote, Never was there a doctrine more calculated to foster indolence, and to blunt the keen edge of curiosity, than this assumption of the discordance between the former and the existing causes of change...

[30] Lyell, in contrast, focused on more recent earthquakes (150 yrs), evidenced by surface irregularities such as faults, fissures, stratigraphic displacements and depressions.

Based on this the third volume of his Principles of Geology, published in 1833, proposed dividing the Tertiary period into four parts, which he named the Eocene, Miocene, Pliocene, and Recent.

[32] The Recent epoch – renamed the Holocene by French paleontologist Paul Gervais in 1867 – included all deposits from the era subject to human observation.

Because this theory could account for the presence of diluvium, the word drift became the preferred term for the loose, unsorted material, today called till.

Furthermore, Lyell believed that the accumulation of fine angular particles covering much of the world (today called loess) was a deposit settled from mountain flood water.

He countered Lamarck's views by rejecting continued cooling of the earth in favour of "a fluctuating cycle", a long-term steady-state geohistory as proposed by James Hutton.

The fragmentary fossil record already showed "a high class of fishes, close to reptiles" in the Carboniferous period which he called "the first Zoological era", and quadrupeds could also have existed then.

In November 1827, after William Broderip found a Middle Jurassic fossil of the early mammal Didelphis, Lyell told his father that "There was everything but man even as far back as the Oolite.

He said in the second volume of Principles that the occurrence of this one fossil of the higher mammalia "in these ancient strata, is as fatal to the theory of successive development, as if several hundreds had been discovered.

[37] The leading man of science Sir John Herschel wrote from Cape Town on 20 February 1836, thanking Lyell for sending a copy of Principles and praising the book as opening a way for bold speculation on "that mystery of mysteries, the replacement of extinct species by others" – by analogy with other intermediate causes, "the origination of fresh species, could it ever come under our cognizance, would be found to be a natural in contradistinction to a miraculous process".

"[39] Whewell subsequently questioned this topic, and in March 1837 Lyell told him:[24] As a result of his letters and, no doubt, personal conversations, Huxley and Ernst Haeckel were convinced that, at the time he wrote Principles, he believed new species had arisen by natural methods.

Lyell was also a friend of Darwin's closest colleagues, Joseph Dalton Hooker and Huxley, but unlike them he struggled to square his religious beliefs with evolution.