Denver Area Geology

Geologic History of the Denver Area

MJD 3/2016 1


The Usual and the Unusual

Geology of the Denver Area By

Michael Delvaux

MJD 3/2016 2


• Disclaimer: This presentation is meant to give an overall top level history (sequence of

events) of the major events that occurred in the Denver area from the beginning of time.

It is not meant to serve any other purpose. The published sources from which many of

the pictures and graphics that were used are listed at the end. There were some

pictures and graphics that were collected from the internet over the years that I do not

have references for. Some of the photographs I have taken myself.

• Due to the uplift of the Rocky Mountains, there are good exposures to a lot of the

geologic history. Unlike other places in the world, there are a number of rather unusual

(not un-natural or un-explainable) things that have occurred here which I have

attempted to point out.

• I have attempted to point out at least one location in the area that contains evidence for

the current theory of these major events.

• For those really interested, I could offer my services up as a guide. Friend me and

message me on my Linkedin site (Public Profilehttps://www.linkedin.com/in/michael-

delvaux-3244052).

MJD 3/2016 3


• Introduction

– 3 Classifications and what they mean

IGNEOUS

SEDIMENTARY

METAMORPHIC

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• Introduction

Igneous Classification

Crystals High Content of In Between Low Content of

Orthoclase Feldspar Mixtures Orthoclase Feldspar

Quartz Quartz

Low Content of High Content of

Plagioclase Feldspar Plagioclase Feldspar

Macroscopic Granite Quartz Monzonite Gabbro

Crystals Granodiorite

Diorite

Microscopic Rhyolite Quartz Latite Basalt

Crystals Dacite

Andesite

Extrusive Behavior Extrusive Behavior

Explosive Volcanic Non explosive

Ash most common non viscous thin

Or thick Volcanic lava

Viscous Lava MJD 3/2016

5


• Introduction

Igneous Rocks – What’s Cool

Different elements and minerals crystalize out of

a cooling magma at different temperatures.

Radioactive Isotope parents

(like U238) crystalize at a

different temperature than their

daughter products (like Pb206).

Since they start at a pure state

they can be used to measure time.

MJD 3/2016 6 Ref: wikipedia


• Introduction

Sedimentary Rocks – What’s Cool

Material is eroded, transported and deposited.

The depositional environments have discernable

recognizable features. Erosion

Alluvial

fan Fluvial

Shoreface Marine

MJD 3/2016 7

Picture Ref: Weimer


• Introduction

Sedimentary Rocks – What Else Is Cool

Rock formations below are older than rock

formations above. Law of Superposition – Nicoli Steno 1669

Rock formations that reside vertically from one

another were deposited horizontally from one

another Walther’s Principle – Johannes Walther 1893 ( first suggested by: Amanz

Gressly 1838)

MJD 3/2016 8


• Introduction

Hundreds

Of

Feet

Hundreds of Miles

MJD 3/2016 9

Example of

Walther’s Principle


• Introduction

That’s cool but what could can an amateur

determine?

Stream and

river current

directions

MJD 3/2016 10


• Introduction

Flow Direction? MJD 3/2016 11


• Introduction

MJD 3/2016 12


• Introduction

Faults

MJD 3/2016 13

Geologic History of the Denver Area • Fossils (from Latin fossus, literally "having been dug up") are the

preserved remains or of animals, plants, and other organisms from

the remote past.

• Trace fossils, also called ichnofossils (sg. pronounced /ˈɪknoʊfɒsɨl/, from

Greek: ιχνος ikhnos "trace, track"), are geological records of biological

activity. Trace fossils may be impressions made on the substrate by an

organism: for example, burrows, borings (bioerosion), footprints and feeding

marks, and root cavities.

MJD 3/2016 14

http://en.wikipedia.org/wiki/Latin

http://en.wikipedia.org/wiki/Wikipedia:IPA_for_English

http://en.wikipedia.org/wiki/Greek_language

http://en.wikipedia.org/wiki/Burrow

http://en.wikipedia.org/wiki/Bioerosion


• Introduction

– Time Chart

MJD 3/2016 15

Picture Ref: Abbott

• Our Story Begins


13Bya 4.5Bya MJD 3/2016 16 Now

First there was the Big Bang



Big Bang

13Bya 4.5Bya MJD 3/2016 17 Now



Big Bang

13Bya 4.5Bya MJD 3/2016 18

Supernovas create heavy elements

Ref: Wikipedia

Now


– Cool Place: Chamberlain Observatory

• Observatory Park, Denver, Colorado


MJD 3/2016 19

Ref: Wikipedia



Big Bang

13Bya 4.5Bya

Solar Nebula

MJD 3/2016 20 Now



13Bya 4.5Bya MJD 3/2016 21

Earth Formation Solar Nebula

Now



Big Bang

13Bya 4.5Bya

Solar Nebula Earth Formation Canadian Shield Begins to form

2.45Bya MJD 3/2016 22

Ref: Abbott, Hoffman Precambrian Now


• Amalgamation of Early North America

(Laurentia)

MJD 3/2016 23

Ref: Hoffman, Jones

13Bya 4.5Bya 2.45Bya

Big Bang Earth Formation

Canadian Shield

Forms

Precambrian Now


• Yavapai Orogeny



Canadian Shield

Forms

1.76Bya

Yavapai Orogeny

Yavapai Orogeny:

Mountain building

as a result of the

accretion of the

Colorado Volcanic

Arc to Laurentia

Precambrian MJD 3/2016 24

Ref: Abbott, Hoffman,

Now




Canadian Shield

Forms

1.76Bya

Yavapai Orogeny

Precambrian

Yavapai Orogeny

Cynobacteria

formed

stromatolites

in the back arc

shallow

environments

MJD 3/2016 25

Ref: Abbott, Hoffman, Snoke,

Knight

Now


• Cool Place: Bioherms (stromatolites) in the

Medicine Bow Mountains of S.Wyoming

MJD 3/2016 26

Ref: Snoke, Knight


• Cool Place: Bioherms (stromatolites) in the

Medicine Bow Mountains of S.Wyoming

MJD 3/2016 27


• Denver Area Rocks of Yavapai Orogeny Time

Gneisses and Schists

Volcanic Arc produced thousands of feet of sediment

of which burial pressure and heat metamorphosed.

Boulder Creek Granodiorite (batholith)

Igneous plutonic rock composed of both plagioclase

and orthoclase feldspars due to the melting and

mixing of both the continental crustal granites and

oceanic crustal basalts

Coal Creek Quartzite

Metamorphosed sandstones and conglomerates from

erosion of mountains and continental rocks.

MJD 3/2016 28

Ref: Cole, Kellog


• Denver Area Rocks of Yavapai Orogeny Time

MJD 3/2016 29

Ref: Kellog


• Mazatzal Orogeny


Big Bang

Earth Formation

Canadian Shield

Forms

1.76Bya

Yavapai Orogeny

Mazatzal Orogeny:

Mountain building

as a result of the

accretion of

succeeding

volcanic arcs.

Precambrian

Mazatzal Orogeny

1.65Bya

MJD 3/2016 30


Now


• No Denver Area Rocks are from the Mazatzal

Orogeny

Gneisses, Schists, and intrusions at the Royal

Gorge are part of the Salida-Gunnison Volcanic

Arc

Transition zone of overlapping Yavapai and Mazatzal

processes.

MJD 3/2016 31



• A third stage set of igneous plutonic pulses

occurred in the Arizona, New Mexico, and

Colorado Area

– 1.50 Bya This pulse did not occur in the Denver

Area

– 1.45 to 1.4 Bya This pulse occurred as the Silver

Plume, Mount Evans, and Longs Peak Batholiths

• Largely granite to granodiorite in composition

• Berthoud Plutonic Suite (Berthoud Orogeny)

MJD 10/2016 32

Ref: Hoffman,


• Iron Dike Intrusion – Dark-gray to black ferrogabbro; weathers dark brown to orange brown with

prominent limonite stains along joint surfaces; very fine grained along dike

margins, and medium grained in centers of thicker dike segments (as wide as 50

ft). Intruded 1,316 ± 50 Ma (Rb-Sr isochron; Braddock and Peterman, 1989). Iron

Dike forms a narrow north-northwest trending swarm that can be traced almost

continuously from eastern margin of Front Range near Boulder, across Estes Park

quadrangle, and beyond into Medicine Bow Range to near Colorado-Wyoming

State line, over a distance of about 95 mi.

– Ferrogabbro composition indicates a deeper mantle source than all previous

igneous intrusions. The cause of this intrusion is unclear.

– Cool location to observe this: Near Boulder and near Estes Park

MJD 3/2016 33

Ref: Kellog

• Grenville Orogeny



Big Bang

Earth Formation

Canadian Shield

Forms

1.76Bya

Yavapai

Orogeny

Precambrian

Grenville

Orogeny

1.0Bya

Grenville Orogeny:

Mountain building

as a result of the

Collision of many

land masses

forming the first

supercontinent,

Rodinia.

MJD 3/2016 34


Now

• Grenville Orogeny



Big Bang

Earth Formation

Canadian Shield

Forms

1.76Bya

Yavapai

Orogeny

Precambrian

Grenville

Orogeny

1.0Bya

Immense collision

forces may have

resulted in

fracturing the crust

and causing rift

zones internal to

the continent

MJD 3/2016

35


Now


• Pikes Peak Batholith

– 3 Intrusive Centers

• Pikes Peak

• Buffalo Park

• Lost Park

– Other Intrusive

Centers may be

buried

– 7 satellite stocks of

non granite igneous

rock are associated.

MJD 3/2016 36

Ref: Abbott, Epis


• Sandstone Dikes

– Extremely unusual feature that occurs within the

Pikes Peak Granite in more than one geographical

location

– Also occurs in biotite gneiss near Arapahoe Pass

in the Indian Peaks Wilderness Area and is

associated with the Arapahoe Pass Fault.

– Explanations vary, but most likely fault induced

fissures into which unconsolidated sand from

aeolian sand dunes fell.

• Likely occurred in the Precambrian between 1.0 Bya and

0.5 Bya. Possibly at the breakup of Rodinia (0.8 Bya).

• Dunes or dune formation eroded during Precambrian

time leaving no other trace of its existence.

MJD 3/2016 37

Ref: Epis, Siddoway


• Sandstone Dikes (Very Unusual)

– Cool Place: Highway 126 (Pine Valley Rd)

Granite Granite

Sandstone

Dike

MJD 3/2016 38

• Cambrian Period

– Explosion of Multicellular Life

– Marks the beginning of the Phanerozoic Eon /

Paleozoic Era

– Earth for the first time had an over abundance

of oxygen which probably lead to the

development of multicellular life



Big Bang

Earth Formation

Canadian Shield

Forms

1.76Bya

Yavapai

Orogeny

Precambrian

Grenville

Orogeny

1.0Bya

Cambrian Period

0.54Bya

Phanerozoic

MJD 3/2016 39

Now

• Cambrian Period -> Ordovician Period

– Started with no deposition and ended with

flooding by shallow sea in Colorado

• Upper Cambrian Sawatch formation marks the

transgression of the sea.

• Cool Place: Sawatch deposited on Pikes Peak

Granite visible in Manitou Springs.


MJD 3/2016

40

Ref: Blakey

• Ordovician Period -> Silurian Period

– Shallow Sea followed by no deposition in

Colorado.


MJD 3/2016 41

Ref: Blakey

• Silurian Period -> Devonian Period

– Shallow Sea transgression across Colorado.

– Eurasian/African Plate encroaches NA plate.


MJD 3/2016

42

Ref: Blakey

• Kimberlite Diatremes – Widespread clusters of deep mantle derived volcanic

activity occurred in the West from Very late

Precambrian through Devonian.

– Source is at depths where pressures are great enough

to form diamonds.

– Volcanism was very violent ripping away wall rocks,

some of which were entombed within the diatreme

pipes themselves.

– Captured wall rocks suggest Silurian/Devonian ages

for diatremes near the CO/WY boarder.

– Some diatremes including the one near Boulder are

Late Precambrian or early Cambrian.


MJD 3/2016 43

Ref: Abbott, Cole Coopersmith, Kellog

• Kimberlite Diatremes


Economics of these diatremes:

0 to 100 carats per 100 tons.

MJD 3/2016 44

Ref: Coopersmith

• Kimberlite Diatremes


Cool Unusual Place near Denver:

Boulder’s Green Mountain Diatreme

MJD 3/2016 45

Ref: Abbott, Nesheim

• Devonian Period -> Mississippian Period

– Shallow Sea still across Colorado.

– Eurasian/African Plate encroaches NA plate


MJD 3/2016 46

Ref: Blakey

• Mississippian -> Pennsylvanian Period


Ancestral

Rockies

Appalachians

Atlas Mtns

MJD 3/2016 47

Ref: Blakey


• The Great Colorado Unconformity

– Uplift of Ancestral Rockies eroded all previously

deposited Sedimentary rocks

– Alluvial deposits (Fountain Formation) on

Precambrian

– Cool Place: Red Rocks Amphitheater

MJD 3/2016 48

• Pennsylvanian Period -> Permian Period


MJD 3/2016 49

Ref: Blakey

• Permian Period – Supercontinent Pangea

– Continued erosion of Ancestral Rockies.

– Large scale wind blown Sand dunes and location

dependent fluvial (stream/river) deposits.

– Cool Places: Lyons Formation in Morrison (contains

very large desiccation cracks. Lyons Formation in Red

Rock Canyon Open Space Park, Manitou Springs

(contains large dune crossbedding, also SS quarry for

building stone ).

– Permian Period ends with the largest extinction event

in geologic history.


MJD 3/2016 50

• Permian Period – Mud cracks (Matthews) or freezing/thawing cracks

(Abbott) in Lyons formation in Morrison city limits.


MJD 3/2016 51

Ref: Matthews, Abbott

• Triassic Period

– No trace of Ancestral Rockies remain

– Lykins Formation

• Low lying mudflats with interfingering marine limestones

• Red iron oxidation suggests arid to semi arid conditions

• Cool places: Within Morrison city limits, South Valley Park, and

above NCAR in Boulder

• Limestones contain stromatolite trace fossils.


MJD 3/2016 52

• Jurassic Period – Breakup of supercontinent Pangea

– Morrison Formation

• Ancient river channel and flood plains deposits

• Red iron oxidation and teal iron reduction in the flood plain /

ancient soils

• Dinosaurs

• Cool place: Dinosaur Ridge (bone site and track site)


MJD 3/2016 53

• Jurassic Period – Morrison Formation

• Cross Section of current ripples at Dinosaur Ridge


MJD 3/2016 54

• Cretaceous Period – Dakota Formation

• Cyclical occurrences of ancient river channel deposits

progressing into tidal flat, shoreface and marine deposits.

• Dinosaurs

• Cool place: Dinosaur Ridge

– Track site – dinosaur and crocodile

– Fossil plant material in channel sands

– Small burrows in tidal flat and shallow marine deposits

– Volcanic ash deposits

• Cool Place: Eldorado Canyon near Boulder

– Tidal Flat and shallow marine / delta deposits


MJD 3/2016 55



Track site

MJD 3/2016 56



U Shaped burrows in Tidal Flat MJD 3/2016 57

• Cretaceous Period – Cretaceous Interior Seaway

• Over 5000 feet of marine deposits

– Benton, Niabrara, and Pierre Formations

• Cool place:

– Dinosaur Ridge – Benton shale

– City of Morrison (along bike trail under C470) – Benton & Niabrara

– NCAR (Boulder) and Red Canyon Open Space (CO Sprgs) – Niabrara

– Rooney Road – Pierre


MJD 3/2016 58



Seaway Deposits

MJD 3/2016 59



MJD 11/2016 60

Ref: Blakey, Wikipedia

• Cretaceous Period – Uplift: Retreat of the Seaway and rise of the Rockies

• Compression in the North American plate caused regional

uplift resulting in regression of the sea.

• Further compression caused major thrust faulting

– Faults extended down into the basement crystalline rocks

– This episode is called the Laramide Orogeny

• Cool place:

– Rooney Road – Fox Hills Formation Delta deposits

– Fossil Trace Golden and CSM Golden – dinosaur tracks in Laramie

Formation

– Bear Creek Reservoir Park (Lakewood) and Marshall Open Space

(Boulder) - Fox Hills and Laramie Formations: beach and swamp (coal)


MJD 3/2016 61

• Cretaceous Period


MJD 3/2016 62

Ref: Abbott

• Late Cretaceous Period


MJD 3/2016 63

Ref: Abbott

• Late Cretaceous Period – KT Boundary

• Most famous extinction event of all (extinction of the

dinosaurs)

• Cool Place: South Table Mountain at about 70 meters below

lava flows on SE side. KT boundary determined from fossil

pollens (clay layer itself is not preserved)

• Cool Place: Clay layer outcrops in Bijou Creek


MJD 11/2016 64

Ref: Kellog, et. al. , 2004

• Paleocene Epoch – Golden Fault was still active

– Erosion continued into the crystalline basement rocks

and formed a rough but gentle sloping eastward plane

called the Rocky Mountain Erosion Surface (parts still

observable today)

– Front Range Volcanoes emerged creating many lava

flows.

– Most of the lava flows eroded and redeposited as stream

bed conglomerates of the Denver Formation.

Occurrences of fossil plant material. Cool Place: lower

half of Green Mountain.


MJD 3/2016 65

• Paleocene Epoch


MJD 3/2016 66

Ref: Abbott

• Paleocene Epoch

– Cool Place: North and South Table Mountains

• 3 lava flows on North Table Mountain

• 2 lava flows on South Table Mountain

• Composition of the lava is called Shoshonite (a

variation of Latite). Mixture of plagioclase and

orthoclase feldspars.

• Contains mineralization

– Zeolite Group: thomsonite, anaclime, chabazite, aragonite,

and others

• Lava source was Ralston Dike located a few miles

north of North Table Mountain.


MJD 3/2016 67

Ref: Drewes 2006, Pearl

• Paleocene Epoch


MJD 3/2016 68

Ref: Abbott

• Eocene Epoch (58 – 37 mya)

– Front Range Volcanoes went extinct.

– Golden Fault went dormant.

– Major erosion period buries the mountains in

their own debris and removes steep slopes.

– Cool Place: Green Mountain Conglomerate

(contains fossil plant and wood material) on

Green Mountain.


MJD 3/2016 69

• Eocene Epoch


(Saprolite – intense chemical weathering of gneiss. Current top of Lookout Mountain)

MJD 3/2016 70

Ref: Abbott

• Eocene Epoch – Ignimbrite Flare-up

• One of the most extensive episodes of high-silica volcanism

(high explosive) in the world

• 6 of the 40 worlds largest eruptions of all time anywhere in the

world occurred in Colorado at this time

• Wall Mountain Tuff was the opening volley with an extremely

large pyroclastic flow.

– Volcanic Source 65 miles to the west near Mt. Princeton – https://www.youtube.com/watch?v=Cvjwt9nnwXY (example)

• Cool place: Wall Mountain Tuff in Rhyolite Park in Castle

Rock. Most of the tuff has been quarried for building material

but some still remains in place.


MJD 3/2016 71

Ref: Abbott

https://www.youtube.com/watch?v=Cvjwt9nnwXY

• Eocene Epoch – Wall Mountain Tuff – Hot incandescent cloud of ash

and gas raced across central Colorado to the vicinity of

Castle Rock in about an hour consuming everything in

its path. As the huge volume of material erupted, the

surface foundered into the magma chamber.


MJD 3/2016 72

Ref: Matthews

• Eocene Epoch – Wall Mountain Tuff


Topography was

different than it is

today

MJD 3/2016 73

Ref: Abbott

• Eocene Epoch – Massive Flooding - Castle Rock Conglomerate

• Extensive flooding brought large stones from as far away as

46 miles (pieces from Coal Creek Quartzite)

• Contains blocks of Wall Mountain Tuff, thus younger than the

tuff itself.

• Cool place: Rock Park in Castle Rock and Castlewood

Canyon State Park


MJD 3/2016 74

Ref: Abbott

• Eocene Epoch – Castle Rock Conglomerate

• Massive flooding carves canyon in

Wall Mountain Tuff.


Topography was


today

MJD 3/2016 75

Ref: Abbott

• Eocene Epoch – Castle Rock Conglomerate

• Massive flooding brings material

from as far away as Boulder CO.


Topography was


today

MJD 3/2016 76

Ref: Abbott

• Eocene Epoch – Florissant Formation

• Guffey Volcanic

eruptions

– After Wall Mountain

– Buries leaves, insects,

and fish in ash

• Lahar ( volcanic mud

and debris flow) buries

Sequoia redwood forest.

• Cool place: Florissant

National Monument


MJD 3/2016 77

Ref: Abbott

• Oligocene, Miocene, and Pliocene Epochs

– Continued regional uplift to 5000 ft

– Erosion: Incision of canyons and valleys in the

mountains


MJD 3/2016 78

Ref: Abbott

• Pleistocene Epoch – Cool Place: Mount Morrison Slide in Matthews Winters

Park. Massive landslide deposit when the valley floor

was not incised as deep as it is today.


MJD 3/2016 79

Ref: Drewes 2005

• Pleistocene Epoch

– Glaciation in the mountains

– Cool Place: Valleys of Rocky Mountain

National Park

– Cool Place: Lamb Spring (Littleton, CO);

Pleistocene animal remains of mammoths,

camels, horses, sloths, llamas and wolves.

~ 13Kya


MJD 3/2016 80

Ref: Web Site

• Modern Times

– Earliest human inhabitants ~8400 years ago as

evidenced by spear points and bison bones at

Lamb Spring (Littleton, CO)

– Magic Mountain Archeological Site (Apex

Open Space) ~ 5000 years human presence

– Plains Indians

– 1858 first white settlement in Denver

– 1970 skyscraper boom


MJD 3/2016 81


• References Abbott,A. and Cook,T. 2012, Geology Underfoot Along Colorado’s Front Range. Mountain Press Publishing Co,

Missoula, MT.

Blakey, Ron, Paleogeography and Geologic Evolution of North America: https://www2.nau.edu/rcb7/nam.html

Cole, J.C., and Braddock, W.A., 2009, Geologic map of the Estes Park 30’ x 60’ quadrangle, north-central

Colorado: USGS Scientific Investigations Map 3039, 1 sheet, scale 1:100,000.

Coopersmith, H., Mitchell, R., Hausel, W., 2003, Kimberlites and Lamproites of Colorado and Wyoming, USA.

Guidebook Prepared for the VIIIth International Kimberlite Conference, Colorado and Wyoming Field Trip 16-21

June2003, Geological Survey of Canada, Ottawa, Ontario.

Drewes, H., Townrow, J., 2005, Trailwalkers Guide To The Dinosaur Ridge, Red Rocks And Green Mountain Area,

Second Edition, Friends of Dinosaur Ridge, Morrison, CO

Drewes, H., 2006, Table Mountain Shoshonite Porphyry Lava Flows and Their Vents, Golden, Colorado, Scientific

Investigations Report 2006-5242, US Geological Survey

Epis, R. and Weimer, R., 1976, Professional Contributions of Colorado School of Mines; Studies in Colorado Field

Geology. Colorado School of Mines, Golden, Colorado.

Hoffman,P. 1988, United Plates of America, The Birth Of A Craton: Early Proterozoic Assembly and Growth of

Laurentia. Annual Review of Earth Planetary Sciences, Vol 16, Palo Alto, CA, Annual Reviews, Inc, p. 543-603.

Jones,D. et at. 2010, New Models for Paleoproterozoic orogenesis in the Cheyenne belt region: Evidence from the

geology and U-Pb geochronology of the Big Creek Gneiss, southeastern Wyoming. GSA Bulletin Vol 122; no.

11/12.

Kellog,K., Bryant,B., and Reed,J., 2004, The Colorado Front Range-Anatomy of a Laramid Uplift, Geological

Society of America Field Guide 5.

Kellog,K., et al, 2008, Geologic Map of the Denver West 30’ x 60’ Quadrangle, North Central Colorado: USGS

Scientific Investigations Map 3000, 1 sheet

MJD 3/2016 82

https://www2.nau.edu/rcb7/nam.html


• References Knight,S.H., 1968, Precambrian staromatolite bioherms and reefs in the lower half of the Nash Formation, Medicine

Bow Mountains, Wyoming: University of Wyoming Contributions to Geology, University of Wyoming, v. 7, no. 2.

Matthews, Vincent, 2009, Messages in Stone Colorado’s Colorful Geology, Colorado Geological Survey, Denver ,

Colorado, Second Edition.

Nesheim, T., 2013, Recent Diamond Exploration In Eastern North Dakota. North Dakota Department of Mineral

Resources Geo News, Vol 40, No. 1, January 2013.

Pearl, R., 1972, Colorado Gem Trails and Mineral Guide, Sage Swallow Press, Athens, Ohio.

Siddoway, C. and Gehrels, G., 2014, Basement-hosted sandstone injectites of Colorado: A vestige of the

Neoproterozoic revealed through detrital zircon provenance analysis. GSA Abstract.

Snoke, Art, August 17, 2013, RMAG Snowy Range, Medicine Bow Mountains, Wyoming Field Trip. University of

Wyoming Unpublished Paper.

Web Site: Lamb Spring Archeological Preserve: http://www.lambspring.org/

Wikipedia, online encyclopedia: https://en.wikipedia.org/wiki/Radiometric_dating

Wikipedia, online encyclopedia: https://en.wikipedia.org/wiki/Supernova

Wikipedia, online encyclopedia: https://en.wikipedia.org/wiki/Western_Interior_Seaway

Weimer,R. ,et al. 2011, A Guide to Mines Geology Trail. Geology Museum Special Publication No 3.

MJD 3/2016 83

http://www.lambspring.org/

https://en.wikipedia.org/wiki/Radiometric_dating

https://en.wikipedia.org/wiki/Supernova

https://en.wikipedia.org/wiki/Western_Interior_Seaway


• Field Trip:

• Bring:

– Water

– Hiking food

– Magnifying glass

– Camera

– Sun Protection (sunscreen, hat, ect)

MJD 3/2016 84

Geologic History of Denver

– Locations:

• Chamberlain Observatory

• Bioherms – Medicine Bow Mtns

• Iron Dike* - Boulder

• SS Dikes – Pine Junction

• Sawatch – Manitou Spgs

• Kimberlite - Green Mountain Boulder

• Red Rocks Amphitheater – Fountain FM

• Lyons: Desiccation Morrison, quarry CO Sprgs

• Lykins: Morrison, South Valley Park, NCAR

• Eldorado Canyon – Fountain – Dakota FMs

MJD 3/2016 85


– Locations:

• Dinosaur Ridge – Morrison FM and Dakota FM

• Benton FM – Morrison

• Niabrara – Morrison, Bear Creek Park, NCAR, Red

Canyon Open Space

• Pierre – Rooney Road,

• Fox Hill, Laramie – CSM, Fossil Trace, Rooney

Road, Bear Creek Park, Marshall Open Space

• Denver Formation – Green Mountain, N and S

Table Mountains

• KT – S Table Mountain, Bijou Creek*

MJD 3/2016 86


– Locations:

• Paleocene – N and S Table Mountains

• Wall Mountain Tuff – Castle Rock

• Castle Rock Conglomerate – Castle Rock

• Florissant

• Green Mountain plant and wood material

• Morrison Slide

• Rocky Mountain National Park

• Lamb Spring*

• Apex Site

MJD 3/2016 87

* Author has not been to this location as of publication