Flora and Fauna Fossil Records are Indicative of Past Climate Conditions

The best barometer we can use to test the character of a climate is the fauna and flora which lived while it prevailed. This is not only the best, but is virtually the only barometer available when we inquire into the climate of past geological ages. Other evidence is always sophisticated by the fact that we may be attributing to climate what is due to other causes; boulders can be rolled by the sea as well as by sub-glacial streams, and conglomerates can be formed by other agencies than ice. But the biological evidence is unmistakeable; cold blooded reptiles cannot live in icy water; semi-tropical plants, or plants whose habitat is in the temperate zone, cannot ripen their seeds and sow themselves under arctic conditions.

Howorth, Henry Hoyle, The Glacial Nightmare and the Flood, 2 vols., London: Sampson Low, Marston & Company, Limited, 1893, vol. 2, p. 427.