Geology Front Range

1 geology

1.1 pikes peak granite
1.2 fountain formation
1.3 lyons sandstone
1.4 lykins formation
1.5 morrison formation
1.6 dakota sandstone
1.7 pierre shale
1.8 denver formation
1.9 castle rock conglomerate
1.10 quaternary deposits

geology

pikes peak , garden of gods.



sandstone slabs along eastern edge of front range


pikes peak granite

about 1 billion years ago, earth producing massive amounts of molten rock 1 day amalgamate, drift , combine, form continents live on today. in colorado region, molten rock spewed , cooled, forming know precambrian pikes peak granite. on next 500 million years, little known changes in sedimentation (sediment deposition) after granite produced. however, @ 500 – 300 million years ago, region began sink , sediments began deposit in newly formed accommodation space. eroded granite produced sand particles began form strata, layers of sediment, in sinking basin. sedimentation continue take place until 300 million years ago.

fountain formation

around 300 million years ago, sinking reversed, , sediment-covered granite began uplift, giving rise ancestral rocky mountains. on next 150 million years, during uplift mountains continue erode , cover in own sediment. wind, gravity, rainwater, snow, , ice-melt supplied rivers carved through granite mountains , led end. sediment these mountains lies in fountain formation today. red rocks amphitheater outside of denver, colorado, set fountain formation.

lyons sandstone

at 280 million years ago, sea levels low , present-day colorado part of super-continent pangaea. sand deserts covered of area spreading dunes seen in rock record, known today lyons sandstone. these dunes appear cross-bedded , show various fossil footprints , leaf imprints in many of strata making section.

lykins formation

30 million years later, sediment deposition still taking place introduction of lykins formation. formation can best attributed wavy layers of muddy limestone , signs of stromatolites thrived in smelly tidal flat @ present-day colorado. 250 million years ago, ancestral rockies burying while shoreline present during break-up of pangaea. formation began right after earth’s largest extinction 251 million years ago @ permian-triassic boundary. ninety percent of planet’s marine life destroyed , great deal on land well.

morrison formation

after 100 million years of deposition, new environment brought rise new formation, sandstone morrison formation. morrison formation contains of best fossils of late jurassic. known sauropod tracks , sauropod bones among other dinosaur fossils. identified fossil record, environment filled various types of vegetation such ferns , zamites. while time period boasts many types of plants, grass had not yet evolved.

dakota sandstone

the dakota sandstone, deposited 100 million years ago towards colorado’s eastern coast, shows evidence of ferns, , dinosaur tracks. sheets of ripple marks can seen on of strata, confirming shallow-sea environment.

pierre shale

over next 30 million years, region taken on deep sea, cretaceous western interior seaway, , deposited mass amounts of shale on area known pierre shale. both thick section of shale , marine life fossils found (ammonites , skeletons of fish , such marine reptiles mosasaurs, plesiosaurs, , extinct species of sea turtles, along rare dinosaur , bird remains). colorado drained being @ bottom of ocean land again, giving yield fossiliferous rock layer, denver formation. @ 68 million years ago, front range began rise again due laramide orogeny in west.

denver formation

front range near estes park, colorado.

the denver formation contained fossils , bones dinosaurs tyrannosaurus rex , triceratops. while forests of vegetation, dinosaurs, , other organisms thrived, reign come end @ cretaceous–paleogene boundary (which known k-t boundary). in instant, millions of species obliterated meteor impact in mexico’s yucatan peninsula. while extinction led demise of dinosaurs , other organisms, life did prevail repopulate earth recovered tremendous disaster. uplifted front range continued erode and, 40 million years ago, range once again buried in own rubble.

castle rock conglomerate

suddenly, 37 million years ago, great volcanic eruption took place in collegiate range , covered landscape in molten hot ash instantly torched , consumed across landscape. entire lush environment capped in matter of minutes 20 feet of extremely resistant rock, rhyolite. however, seen before, life rebounds, , after few million years mass floods cut through rhyolite , eroded of plants , animals began recolonize landscape. mass flooding , erosion of volcanic rock gave way castle rock conglomerate can found in front range.

quaternary deposits

eventually, @ 10 million years ago, front range began rise again , resistant granite in heart of mountains thrust upwards , stood tall, while weaker sediments deposited above eroded away. front range rose, streams , recent (16,000 years ago) glaciations during quaternary age literally unburied range cutting through weaker sediment , giving rise granitic peaks present today. last step in forming present-day geologic sequence , history of today’s front range.

the front range viewed greenwood village south of denver, mount evans on far right