Nicolas Desmarest

Nicolas Desmarest (16 September 1725 – 20 September 1815) was a French geologist.
Desmarest was born at Soulaines in the department of Aube in France. He was educated at the college of the Oratorians of Troyes and Paris. While doing this, he earned money by teaching, to pay for his education. 
Buffon's "Theory of the Earth" interested him, and in 1753 he won a prize by writing an essay on the ancient connection between England and France. A lot of people were interested in this. He was given job studying and reporting on manufacturing in different countries. In 1788 he became inspector-general of the industries of France.
Demarest travelled around on foot to learn more about the Earth's structure. In 1763 he noticed that the basalt rocks in Auvergne were old lava streams. He noticed that they were similar to the columns of the Giant's Causeway in Ireland. He knew that they were evidence of the operations of old volcanoes which were no longer active. 
In 1774 he published an essay on the subject (with a geological map) after visiting the area a few times. He then discussed the changes that the rocks had gone through because of weathering and erosion. This was the first time that anyone had talked about valleys being made because streams which flowed through them eroding the rocks.
He died in Paris in 1815. In 1823 his son Anselme Gaëtan Desmarest published a new and better edition of his map.