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Roadside Geology of Colorado’s Highway 149Creede to Spring Creek PassAs you are driving along Highway 149, imagine that this landscape was an erupting volcano millions of years ago, spewing out rocks the size of houses. This area is part of a giant crater known as the Creede Caldera. Stop 1. Airport Corner. At this location numerous plant fossils, mineral impressions and occasional insect fossils may be found on the hill to the north side of the road by parting the thin layered rock. After the formation of the Creede Caldera, a salty lake formed in the crater, which received palnt debris and sediment as they eroded down from the surround hills. This sediment eventually turned into rock that is mostly composed of very fine grained volcanic ash. Stop 2. Point of Rocks. This area, just off Hwy 149 on Middle creek Road, is interesting because you can see several types of rocks from two different calderas. The Bachelor Mountain Member of the Carpenter Ridge Tuff was a flow of volcanic ash that erupted from the Bachelor Caldera, which is located somewhat north of, and predates by several hundred thousand years, the Creede Caldera. Near this formation is an outcrop of breccia (pronounced “bret’-shia”), composed of broken, angular rock fragments. Also at this stop is an outcrop of Snowshoe Mountain Tuff (another volcanic ash deposit) that erupted from the Crede Caldera about 27 million years ago. Stop 3. Entrance to Rio Grand Campground. Here you’ll see an example of a lava flow overlying a debris flow, both associated with the first and by far the largest of the calderas to from in the area, the 1000-square mil La Garita Caldera. Stop 4. North Clear Creek Falls. Here, North Clear Creek suddenly tumbles over tuff that erupted from he San Luis Caldera Complex – a family of three calderas that formed over a short period of time north of and probably slightly before the formation of the Creede Caldera. RockHounding in Mineral County1) Pool Table Road 2) City Dump Road 3) Airport Corner 4) Four Wheel Drive For more information or maps on Geology and RockHounding in the Creede and Mineral County area, please contact the Creede and Mineral County Chamber of Commerce. |
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