From the Hall of Disjointed Memories, Part 32: Mood Maroon | Eagle County, Colorado, USA
Snapped with my high-performance Kodak Instamatic along the northern side of Interstate 70, about 6.5 road mi / 10.5 km east of the town of Eagle. I’m facing westward.
After posting three “I’m not sure where I am” photos in this series, I’m delighted to say that I know precisely where this pic was taken. But sleuthing out its location took a long while. Fortunately, this spot is well-known to Colorado geologists and other images of it can be found online and in one of my sources for this series:
- Matthews, Vincent. Messages in Stone: Colorado’s Colorful Geology. 2nd ed. Denver: Colorado Geological Survey, 2009.
In fact, this place seems to have long been a popular field-trip stop. I do not recall what my professors told my group here, but I’m sure it was some sort of description, however mumbled or reduced to reductionist arcanities, of the redbeds jutting out of the mesa spur directly in front of us. They are a splendid exposure of the Middle Pennsylvanian (Upper Carboniferous) to Lower Permian Maroon Formation.
That colorful unit is composed of sediments washed down from either the Ancestral Uncompahgre Uplift, which stood a little to the west of here, or the Ancestral Front Range Uplift, just to the east. I’m not sure which of these was the more likely source. Even the most detailed of my references does not speak to this locale specifically. That reference, incidentally, is Samuel Y. Johnson’s “Sedimentology and Paleogeographic Significance of Six Fluvial Sandstone Bodies in the Maroon Formation, Eagle Basin, Northwest Colorado,” in Evolution of Sedimentary Basins-Uinta and Piceance Basins, U.S. Geological Survey Bulletin 1787 (1987).
The two ranges mentioned in the previous paragraph were part of the Ancestral Rockies that rose, we know not exactly why, at about the same time the Alleghenian and Ouachita Orogenies were occurring much farther south and east. Were the Ancestral Rockies triggered by the assembly of Pangaea, too? But if so, they lay suspiciously far from any continental collision zone.
Geologists have come up with several different clever hypotheses explaining why these mountains formed so deep in the North American interior. And so far hypotheses they remain. But one way or another, stresses in the lithosphere did exert themselves in this region in such a way that the predecessors of Colorado mountain chains we see today came into being late in the Paleozoic era.
You'll find the other photos and descriptions of this series in my From the Hall of Disjointed Memories album.
From the Hall of Disjointed Memories, Part 32: Mood Maroon | Eagle County, Colorado, USA
Snapped with my high-performance Kodak Instamatic along the northern side of Interstate 70, about 6.5 road mi / 10.5 km east of the town of Eagle. I’m facing westward.
After posting three “I’m not sure where I am” photos in this series, I’m delighted to say that I know precisely where this pic was taken. But sleuthing out its location took a long while. Fortunately, this spot is well-known to Colorado geologists and other images of it can be found online and in one of my sources for this series:
- Matthews, Vincent. Messages in Stone: Colorado’s Colorful Geology. 2nd ed. Denver: Colorado Geological Survey, 2009.
In fact, this place seems to have long been a popular field-trip stop. I do not recall what my professors told my group here, but I’m sure it was some sort of description, however mumbled or reduced to reductionist arcanities, of the redbeds jutting out of the mesa spur directly in front of us. They are a splendid exposure of the Middle Pennsylvanian (Upper Carboniferous) to Lower Permian Maroon Formation.
That colorful unit is composed of sediments washed down from either the Ancestral Uncompahgre Uplift, which stood a little to the west of here, or the Ancestral Front Range Uplift, just to the east. I’m not sure which of these was the more likely source. Even the most detailed of my references does not speak to this locale specifically. That reference, incidentally, is Samuel Y. Johnson’s “Sedimentology and Paleogeographic Significance of Six Fluvial Sandstone Bodies in the Maroon Formation, Eagle Basin, Northwest Colorado,” in Evolution of Sedimentary Basins-Uinta and Piceance Basins, U.S. Geological Survey Bulletin 1787 (1987).
The two ranges mentioned in the previous paragraph were part of the Ancestral Rockies that rose, we know not exactly why, at about the same time the Alleghenian and Ouachita Orogenies were occurring much farther south and east. Were the Ancestral Rockies triggered by the assembly of Pangaea, too? But if so, they lay suspiciously far from any continental collision zone.
Geologists have come up with several different clever hypotheses explaining why these mountains formed so deep in the North American interior. And so far hypotheses they remain. But one way or another, stresses in the lithosphere did exert themselves in this region in such a way that the predecessors of Colorado mountain chains we see today came into being late in the Paleozoic era.
You'll find the other photos and descriptions of this series in my From the Hall of Disjointed Memories album.