Originally posted by RICHARD L. This is not 1) Volcanic rock (like we see in Grants, New Mexico) or 2) Sandstone (like we see in Arches Nat'l Park, Utah). This looks like Granite and glaciers bulldozed and tumbled these very hard rock formations.
Volcanic rock crumbles and disappears over time, being light and porous. Sandstone is sculpted by wind erosion and by cycles of water freeze and thaw. It took enormous energy to move heavy Granite around.
Regards
Not volcanic in the sense it came from a volcano but it is of the same origin, magma. Magma that cooled much more slowly than magma that comes out as lava. If these rocks were moved by glacial activity it wouldn't have been very far since they formed right here. It's definitely granite. The granite for the Colorado State Capitol building was quarried nearby.
From USGS:
Quote: Intrusive Igneous Rocks:
Intrusive, or plutonic, igneous rock forms when magma is trapped deep inside the Earth. Great globs of molten rock rise toward the surface. Some of the magma may feed volcanoes on the Earth's surface, but most remains trapped below, where it cools very slowly over many thousands or millions of years until it solidifies. Slow cooling means the individual mineral grains have a very long time to grow, so they grow to a relatively large size. Intrusive rocks have a coarse grained texture.
Most of the rocks are not loose like this balanced boulder and it generally looks more like the first photo in the set (which has the eroded remains of a long-dormant ancient volcano in the distance).
Last edited by mattb123; 11-15-2021 at 03:43 PM.