Definitions for "Altithermal period"
The period from about 5000–2500 B.C., proposed by Ernst V. Antevs (1952), during which the summer temperature of western North America was 1°–2°C warmer than today and during which the lakes of the American Great Basin dried.
A dry, warm postglacial period 7500-4000 ybp ( cf. Little Climatic Optimum).