Igneous rocks of Colorado. Cross sections showing different kinds of igneous intrusions

Uploaded: Jan. 15, 2014, 2:32 p.m. | Modified: Nov. 15, 2015, 10:15 a.m. | Albums: Colorado Igneous Vignette
This animation is an excerpt from the "Colorado Geology: late Eocene to middle Miocene Igneous History" video (in progress). This animation was developed to illustrate the origins of two kinds of igneous intrusions in a cross sectional view of the Earth.

0 to 8 seconds: The scene shows igneous magma intruding vertically through the rock, and then intrudes laterally into the flat-lying rocks. The continued pooling of magma at the shallower level causes uplift on the overlying strata. The shallow igneous feature is called a laccolith. This animation specifically shows the origin of.the Spanish Peaks, southern Colorado (~ 24 to 25 million years ago).

8 to 24 seconds: The scene shows igneous magma intruding vertically through the rock, and then intruding laterally into the flat-lying rocks. The continued pooling of magma evolves as a magma chamber. The magma eventually erupts on the surface creating volcano.

24 to 31 seconds: As the magma under the volcano cools, the area begins to collapse below the surface and a caldera forms. Ancient calderas are present in several locations in southwestern Colorado (Silverton, Lake City, Creede, La Garita calderas), which all developed between 28 and 22 millions years ago.

Animation is created by James Adson, Joseph Rogers, and Eric Lobato. A special thanks to Chuck Stern and Lang Farmer for their technical input.

Interactive Geology Project, University of Colorado-Boulder. igp.colorado.edu