Horizontal andesite columns on Pinnacle Peak trail, WA. Predate Mount Rainier (pre-eruption). Approximately 23-25 million years. Honeycomb, specific 4-6 sided and when solidifying/cooling lava flow contracts and naturally breaks, forming similar to mud cracks. Horizontal (vs. vertical) only happens when comes in contact with a glacier. These differ from the Columbia River "basalts."