I also found them in Garden of the Gods near Colorado Springs, Colorado. When they increased the LOD, it means that raised areas of elevation that were not visible at lower LOD become visible, but there’s not enough further resolution to make those areas look smooth (without a programmatic way of either ignoring them or extrapolating the curve between points.)
At least that’s what I imagine is going on. The opposite problem (not enough resolution) is what people are complaining about in mountainous regions, which is why they look too smooth. Basically, areas of dramatic elevation change (compared to the LOD / resolution) is what produces these artifacts.