During this period he became interested in evolution and constructed a workshop, which he called his laboratory, which he used to take pictures of microscopic organisms and other objects to illustrate his lectures and books, though rarely for actual experiments. Rimmer enrolled in a correspondence course in geology (at the University of Colorado, while on a speaking tour in the Rocky Mountains region) and started collecting fossils. Thereafter his lectures increasingly featured evolution and he acquired a reputation among fundamentalists as a qualified critic of evolution, with a fundamentalist journalist declaring: