Question

The Columbia Plateau exposes dark rock that spans the states of Washington, Oregon, and Idaho. What made this va plateau?

Answer 1

Basaltic lava

Step-by-step explanation:

Such a high volume of basaltic lava is erupted that the lava flows flood the land's surface. Between 15 and 6 million years ago, basaltic lava flooded approximately 163,000 square kilometers (63,000 square miles), covering large parts of Washington, Oregon, and Idaho (Figure 2.35).