Dec. 15, 1869 – May 4, 1919
From Today In Science History:
Barrell was an American geologist who proposed that sedimentary rocks were produced by the action of rivers, winds, and ice, as well as by marine sedimentation. In 1916, he indicated that the coloration of many Devonian rocks was bright red because they had been baked dry, like bricks, in arid conditions. Also, this severe climate was a driving force in the evolution of air-breathing vertebrates, including tetrapods.
In 1917, he used the new results of radioactive dating to reinterpret Earth's age at a few billion years, though many geologists still preferred an age of 100 million years. Barrell emphasized that geological processes vary in intensity in a cyclical rather than a uniform fashion, thus current rates of geological change should not be used as a guide to the past,as in prior estimates.