Around 4,500 years ago, the temperature increased into the Altithermal, reaching a maximum warmth and dryness. This was followed by the Medithermal coming back to modern conditions. The Early Archaic roughly corresponds to the Anithermal . This mixed economy is the difference between the earlier hunting based Paleo-Indian period and the later Archaic traditions. Hunting concentrated on elk, deer and antelope.
Fishing is now importance, a pattern that marks the Columbia River groups from then on.
Fishing gear such as net sinkers, fish hooks and fish spears appear. Food storage pits are recorded in sites. Metates and manos reflect an increasing use of plant foods. Woven textiles, baskets, nets, mats, and sandals appear in the archaeological record. The atlatl is still the primary hunting weapon, but hunting and gathering tool kits diversify.