Charles Darwin was a geologist, great collector, and was the English naturalist who provided evidence of what he liked to call natural selection. Natural selection is a process where the popular, or dominant traits become more and more often seen as generations of an organism go on. While evolution became believed by many while he was alive, natural selection was not widely accepted until the 1930's, after his death in 1882. This was so because during his lifetime people were devout followers of the bible, and what he said did not match what the bible said, therefore they believed it incorrect.
Charles Darwin studied medicine at Edinburgh University and Theology at Cambridge University; this is what got him interested in the world of natural history. He then took a five year trip on The Beagle, a ship that took him to the Galapagos Islands. He was a collector, and while he was on the trip he collected many items, such as fossils, which started him on the track of evolution and to his idea of natural selection, although he would not bring it up for years. When he came back, after the voyage of the Beagle, his journal that he had written on the trip was published and he became a famous author.
He was greatly influenced by Charles Lyell, who had brought up geologic time, that the earth is a lot older than they thought it was at the time. During that period of time they thought that the earth was a few thousand years old, geologic time means that the earth is not thousands, but billions and billions of years old. This was important to the discoveries of Darwin, because without that amount of time, the organisms on the earth could not have had time to evolve with natural selection.
After years and years of research and various opinions of other geologists around the world, he began to write his theory. While he wrote his theory of natural selection when another geologist named Alfred Russel Wallace sent him an essay. The essay held a theory surprisingly similar to Darwin's own theory of natural selection. They then realized how fortunate this was and published their theories together with the help of Charles Lyell, Darwin's influence and close friend. It was then that the world of science began to look into natural selection and although it took sometime for everyone to come around to the idea, it has now changed the world of geology, zoology, and most importantly science forever.