Had to fit many processes into a short time scale. Published Theory of the Earth in 1785. Hadrian's Wall built by Romans, after 1500 years no change. Suspected that Earth was much older.
Slow processes shape earth.
Quantitative scientific methods. In 1897, Lord Kelvin assumed that the Earth was originally molten and calculated a date based on cooling through conduction and radiation. Age of Earth was calculated to be about 24-40 million years. River water has only a small concentration of salts. Rivers flow to the sea.