Columnar basalt has to be one of the most interesting things, in my opinion, about the Columbia River Gorge. You can see it in the walls of Latourell Falls just below the large section of lichen in the top right. So how do those columns form? First you need these ingredients: a volcano, an eruption, and lava. As lava cools it contracts and as a result of the rapid cooling it fractures. The fractures that start at the top of the column typically will continue down the lava as it cools, forming the long accentuated columns that we see so prevalent in the gorge. All these fractures make columnar basalt vulnerable to weathering, as evidence by the piles of broken rock at the bases of many of the Gorge's waterfalls.