Here we see a recent lava flow, about 3000 years old, butting up against the gentle slope of the eastern edge of the Western Cascades. A thick stand of old growth Douglas fir covers that slope. 3000 years is enough time for the same trees to get established, and grow quite large, on the flow, but a seed has to be quite lucky to sprout in a spot that's just right to support it. The tree along the upper right edge is one such example. As a result, the mature trees out on the flow aren't necessarily much smaller than those on the slope, but they're much sparser.
Also, across the middle, we see another flaming swath of vine maples in their fall colors.