In the northeast corner of the state lies the Modoc Plateau, an expanse of lava flows that formed a million years ago and now lie at an altitude of . The plateau has many cinder cones, juniper flats, pine forests, and seasonal lakes. The plateau lies between the Cascade Range to the west and the Warner Mountains to the east. The Lost River watershed drains the north part of the plateau, while southern watersheds either collect in basin reservoirs or flow into Big Sage Reservoir and thence to the Pit River.