Agassiz Louis

Agassiz

, (Jean) Louis (Rodolphe) 1807-1873. Swiss-born American naturalist noted for his study of fossil fish and for recognizing from geologic evidence that ice ages had occurred in the Northern Hemisphere.

Ag·as·siz

(ăg′ə-sē), (Jean) Louis (Rodolphe) 1807-1873. Swiss-born American geologist and zoologist who in 1840 introduced the idea of the ice age. Agassiz carried out extensive fieldwork in Europe and the United States which led him to theorize that most of the Northern Hemisphere had once been covered by a vast sheet of ice. Earlier in his career, Agassiz published a groundbreaking study of fossil fish and was known as the greatest ichthyologist of his day.