How do you turn granite (that is normally split into cubes by joints) into rounded boulders that are seen all over this virtual field trip? Group of answer choices When the joint fractures come into contact with ground water that seeps into the cracks. This all takes place meters beneath the surface, where chemical decay weathers the minerals into grus (granite sand). Corners of the cube have three joints that intersect, so the corners decay the most. Decay on the corners gives the boulder a "spheroidal" shape. This rounding still takes place all in the subsurface where you can't see the boulders (except in road cuts). Granite starts out in the subsurface already fractured by "joints". The pattern of fracturing splits granite into blocks that are cube-like in shape. All of the other answers are correct, and thus this is the best answer. Erosion of the decayed granite (grus) exposes these boulders at the surface. Spheroidally-weathered boulders are "born rounded" by subsurface mineral decay (subsurface weathering)