Huerfano County, Colorado
The Cuchara River Valley

The Cuchara River Valley is in the middle of a beautiful anomaly on the face of the Earth. The Ancestral Rockies were pushed up just west of here about 65 million years ago during the Laramide Orogeny. Over the years, they eroded away but certain portions of the Dakota Wall withstood the test of time and were still standing upright on the surface when the next active phase of mountain-building began about 30 million years ago. When the Sangre de Cristo's were pushed up as a fault-block, they broke through the horizontal layers of sandstone and turned portions of that broken rock upright in their passage. Some sections of Dakota Formation Sandstone broken and turned upright 65 million years ago still stand in places along the western slopes of the Sangres. Along the eastern slopes of the Sangres are upturned plates of Dakota Sandstone broken during the uplift 27 million years ago. However, for some reason that uplift of mass Pennsylvanian-Permian rock that forms the backbone of the Sangre de Cristo Mountains was interrupted in this area. The fault lines on both sides of the block run north from the Culebra's to Mt. Seven and Tijeras Peak and flow north along both sides of the Sangres up to the area of Poncha Pass but from just north of Raspberry Mountain to about Mt. Seven there is a break in that uplifted block of rock. With the millenia-old plume of magma rising from the center of the Earth pushing this action for at least 40 million years at that point, this must have caused some strain in the ground.

About two million years later, just east of the fault lines that line the fault-block uplift, the molten magma that pulsed in that upward surge from the Earth's core flowed into cracks and holes below ground and solidified but never reached or erupted on the surface. 25 million years later, here we are looking at what's left after all this time.

The East Spanish Peak shows evidence of two different magma flows. The West Spanish Peak was formed by the second of the flows that formed the East Peak. The Great Dikes that radiate outwards from the West Peak were also formed in this second flow. The three White Sisters that rise along the east side of Cuchara are from this second flow, too.

Across the valley to the north, Silver Mountain rises in the center of another set of radial granite dikes. To the west and running northerly along the east side of the Sangre de Cristo's fault lines, rise Mt. Mestas, Rough Mountain, and Sheep and Little Sheep Mountain. Dikes run east from Silver Mountain into the Black Hills of central Huerfano County. Other dikes continue to the northeast and run up along the flank of the Wet Mountains, past Badito Cone and up to that mound of porphyry with 5 or 6 peaks that we call Greenhorn Mountain. From Little Sheep Mountain south, past Mt. Mestas and almost to Raspberry Mountain, beneath the ground is a huge carbon dioxide bubble capped by the southernmost glacier in North America.

The Apishapa Uplift, an underground feature extending east from the East Spanish Peak past the Hogback, acts as a dividing line in one important way: the coal south of the Uplift burns cleaner and contains lots of methane gas while the coal north of the Uplift burns dirtier and contains little methane gas. The many layers of coal beneath us (each layer separated from each other by millions of years of time and geological change as measured in the layered depositions of sandstone, limestone and shale) are composed of the organic remains of the forests and other vegetation that died and began that metamorphosis, the most recent being 100 million years ago, well before the Laramide Orogeny. This geographical difference in the sulphur and phosphorus content of millenia-old vegetation speaks of variations of minerals and elements in the flow of magma around the Earth's core going back to the birth of the planet.

When we're looking at these things, it helps to remember that when all of this rock solidified, the top of the West Spanish Peak (now at 13, 656') was approximately two miles underground. We're seeing the results of 25+ million years of erosion. And if you look closely, you can see all of this geological story written clearly on the face of the Earth.