John Joly

“The surface-history of the Earth is a history of revolutions.”

“The evidence which has accumulated in recent years is such as to force us to the conclusion that the great features of the earth's surface have been produced by periodic compressive and tensional stresses acting in the crust.”

“We can not, however, be sure that the present supply of heat from radioactivity has been maintained uniformly throughout all geological time.”

“A colour photograph is a history of the light which fell upon it.”