# On the Lapse of Time, as Inferred from the Rate of Deposition and Extent of Denudation explained — The Origin of Species > Chapter companion for The Origin of Species by Charles Darwin. ## What happens Darwin argues that the immense periods of geological time, as inferred from rates of deposition and denudation, are sufficient for the slow process of natural selection to produce organic change. He emphasizes the power of subaerial degradation over coastal erosion, citing Lyell, Ramsay, and Croll, and uses the thickness of sedimentary strata and the slow wearing of rock to illustrate the vastness of geological time. He concludes that species change slowly, but that the time available is adequate for evolution. ## Themes in this chapter ### Imperfection of the Geological Record The chapter uses the slow rate of deposition and denudation to explain why transitional forms are rare in the fossil record. ### Natural Selection and the Struggle for Existence Darwin argues that the vast time available allows natural selection to slowly modify species. ## Character check-ins ### Charles Darwin Author and narrator, presenting geological evidence for the vastness of time. ### Sir Charles Lyell His 'Principles of Geology' is cited as foundational for understanding geological time. ### Professor Ramsay His observations on subaerial degradation and measurements of strata thickness are key evidence. ### Mr. Croll His calculations on denudation rates and illustration of a million years are used to convey the scale of time. ## Key lines > 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, and yet does not admit how vast have been the past periods of time, may at once close this volume. Anyone who reads Lyell's 'Principles of Geology' and still denies the immense age of the Earth should stop reading this book. _Darwin emphasizes Lyell's revolutionary impact on understanding geological time._ > Nothing impresses the mind with the vast duration of time, according to our ideas of time, more forcibly than the conviction thus gained that subaerial agencies, which apparently have so little power, and which seem to work so slowly, have produced great results. The slow but cumulative effects of rain, wind, and chemical weathering on the landscape powerfully convey the enormity of geological time. _Darwin highlights the contrast between the apparent weakness of subaerial forces and their massive long-term effects._ > Few of us, however, know what a million really means: Mr. Croll gives the following illustration: Take a narrow strip of paper, eighty-three feet four inches in length, and stretch it along the wall of a large hall; then mark off at one end the tenth of an inch. This tenth of an inch will represent one hundred years, and the entire strip a million years. To grasp a million years, imagine a paper strip 83 feet 4 inches long; a tenth of an inch represents a century, and the whole strip a million years. _Croll's visual analogy helps readers comprehend the vastness of geological time._ ## Links - HTML: https://www.betterreads.online/discover/the_origin_of_species_se/chapters/on-the-lapse-of-time-as-inferred-from-the-rate-of-deposition-and-extent-of-denudation - Book: https://www.betterreads.online/discover/the_origin_of_species_se - All chapters: https://www.betterreads.online/discover/the_origin_of_species_se/chapters