[Due to the addition of a shaded relief base, colors on the List of Map Units and the Correlation 

of Map Units may not exactly match unit colors on the map]

10

40

30

45

65

25

10

70

75

20 70

80 60 75

20

33 70

60

10

75

68

28 40

43

45

50 45

60 60 70

61

60

80

60

85

60 55

62

47

65

80 80

70

70

40 30

85

70 80

75

60

75

65

55

55

60

80

70

60

85

65

75 80

80

80

20

45

60

75

75

70

70

45

63

60

60

62

70

75

52

75

70

70

65

70

70

85

79

70

65

87

80

80

70

60

80

55

85

10

30 25

9

50 20 50

58

47

69

56

70

64

55

65

25

25

50

GR11–725

42.25 ± 0.13 Ma

GR11–711

24.12 ± 0.12 Ma

WRP03–6B

1436 ± 6 Ma

USGS(D)G–A–82

65.3 ± 2.4 Ma

GR10–511

1434 ± 7 Ma

GR11–756

24.3 ± 0.6 Ma

Qopy

Ygl

pt

af

Qoey

Nd

Qobo

Qc

Qc

Qva

Qte

Qls

Qc/Nd

pt

Ygr

mt

Qc

Qoey

Qopo

af

Qac

Nd

Qc/Nd

Qc

Qc

Qsw/Nd

Qrg

Qoby

Qtpy

Qc

YXp

Ygrg

af

Qc

Qc

Qobo

Qac

Qoeo

af

Qopy

Qac

Qopy

Qc

Qac

Qva

Qf

Qc/Nd

Ygrg

Qtpy

Qc/Nd

Ygrg

Qopy

Qopo

Qta

Qc

Qac

Qls?

Qc

Ygrg

Qtpy

Qac

Qoby

Qoey

Qac

Xgb

Qc

Qc

Qc

Qopy

Ygrg

Qac

Qopo

Qc

Ygrg

Qac

Ygrg

Qtpo

Qtpy

Qoby

Qoby

Qf

Ygrg

Qoeo

Qtpo

Qc

Qtpo

Qtb

Qc

Nd

af

Qoey

Qoby

pt

pt

af

Xlg

Qobo

Qoeo

Qc

Qopy

Qb

Qte

pt

Qac

Qf

Qopy

Qb

Qopy?

Ygl

af

Qoey

Qtb

Qoey

Qopo

Qc/Nd?

Qls

Qac

Qc

Qc

Qopy

Xhg

Qoey

Ygl

Qtpy

Ygr

Qf

Qtpo

Qoey

Qc

af

Qta

pt

Ygl

Qopy

Qac

Ygrg

Qc

Xb

Xgg

Nd

Qc

af

Qc

Qc

Qopo?

Ki

Qc

Qoey

Qta

YXp

Ygrg

af

Qta

Qf

Qac

Qc

Qac

Ygrg

Qac

Qrg

Qac

Qtpy

Qtpy

Xb

Qoby

Ygl

Qf

Qac

Nd

Xb

Qac

pt

Qoey

Qtpy

Qoey

Xb

Qopy

Qf

Qopo

af

Qls

Qc/Nd

Qac

Qtb

Qf

Qopy

Qac

Qtpy Qtpo

Qf

Qopy

Qac

Qc

Qc

Xb

Qopy?

Qopo

Qc

Qc

Qtpy

Qls

Qoeo

pt

Qls

Qta

Qc

Qf

Qopy

mt

Qls

Qc

Qac

Qls

Qf

Qac

Qc/Nd

Qac

Qta

va

Xlg

Qc

Qls

Qc

Qopo

Nd

Qopy

Ygrg

Ygrg

Qf

Qc/Nd

Qc

Xgg

rc

va

Qc

Xb

Qls

Qb

Qac

Qc

Qte

Qac

Qac

Qta

Qoby

Nd

Qls

Qtpy

Nd

Ygrg

Qc

Qoey

Qac

Qc/Nd

Qopo

Qoey

Qls

Qsw/Nd

Qtpy

Qoey

Ygrg

Qc

pt Qc

Qac

af

Qac

Qc/Nd

Qls

Qac

Qtpy

Qac

Qc

Xlg

Qopo?

Qc

Qsw

Qtpy

YXp

Qc/Nd

pt

Qsw/Nd

Qva

Qta

Qls

Qopy

mt

Qf

Ygrg

af

Qte

Qc

Qte

Qf

Qta

Qf

Xb

Ygrg

Qc

Qopo

Qc

af

Qls

Xlg

Ygrg

Nd

Ygrg

Qls

Qac

Qopy

Ygrg

Qtpy

Qc

Qoey

wf

Qls

Qc

Xb

Qac

Qc/Nd?

Qf

Qc

af

Qopy

Qc

Qc/Nd

Qtb

Qopy

Qls

Qoeo

Qsw

Qc

Qf

Qtpo

Qopy

Qc

af

Ygrg

Xb

Qta

Qopy

Qc

Qc

Qtpy

Qopy

Qc

Qac

Qopy

Qtb

af

Qac

Qtpy

Qoeo

Qls

Qf

pt

Qc

Nd

Qc/Nd

Qobo

Qoby

Qls

Qoby

Qc/Nd

Qls

pt

Ygrg

Ygl

Qtpy

Qte

Qls

Nd

mt

Qopy

pt

Qls

Qf

Qf

Qopo

Qc

Ygl

Nd

Qc

Qoey

Qac

Qtpy

Qva

pt

Qac

Qtpy

Qc

Qac

Qoeo

Qf

pt

Qtpy

Qc

Qac

Qc

Qc/Nd?

Qtpy

Qc

Qopy

Qac

Qac

Qopy

Qac

Qls

Qopy

Qoey

Ygrg

Qc

Qta

Ygr

Qoey

Xb

af

Qls

Qopy?

Qc

Qac

Qoeo

Qc/Nd

wf

Qta

Qtb

Qsw

Qte

Qoby

dt

Nd

Qc/Nd

Qoey

af Qtpy

Qf

Qac

af

Qc

Qc

Qf

Qc/Nd

Qc

Qopo

Qoey

pt

Qsw

Ygrg

Qf

Qopo

Qf

af

Ygl

Qac

Qta

Qls?

Qopy

pt

Qls

Qtpo

Xb

Qopy

Qva

Yglf

Qte

Qtpy

Qc

Qva

Ygr

Yglf

Qtpo

Qtpo

Qls

Kr

Kr

wf

wf

wf

wf

wf

wf

wf

wf

wf

wf

wf

wf

Ygr

wf

Qc

Ygrg

LIST OF MAP UNITS

SURFICIAL DEPOSITS

Manmade deposits

Artificial-fill deposits (latest Holocene)

Placer-tailings deposits (latest Holocene)

Mine-tailings deposits (latest Holocene)

Lacustrine deposits

Beach deposits (latest Holocene)

Alluvial deposits

Valley-floor alluvium (Holocene and latest Pleistocene?)

Sheetwash alluvium (Holocene and late Pleistocene)

Sheetwash alluvium over Dry Union Formation

Outwash of Pinedale age (late Pleistocene)

Younger unit

Older unit

Outwash of Bull Lake age (late and middle Pleistocene)

Younger unit (late and middle Pleistocene)

Older unit (middle Pleistocene)

Outwash of pre-Bull Lake age (middle Pleistocene)

Younger unit

Older unit

Alluvial and mass-movement deposits

Alluvium and colluvium, undivided (Holocene to middle? Pleistocene)

Fan deposits (Holocene to middle? Pleistocene)

Mass-movement deposits

Talus deposits (Holocene to middle? Pleistocene)

Colluvium (Holocene to middle? Pleistocene)

Colluvium over Dry Union Formation

Landslide deposits (Holocene to middle? Pleistocene)

Glacial deposits

Rock-glacier deposits (early Holocene? and latest Pleistocene?)

Till of Pinedale age (late Pleistocene)

Younger unit

Older unit

Till of Bull Lake age (late and middle Pleistocene)

Till of pre-Bull Lake age (middle Pleistocene)

BEDROCK UNITS

Post-volcanic sediments

Dry Union Formation (lower Pliocene? and Miocene)

Volcanic rocks

Vesicular andesite flow (upper Oligocene)

Hypabyssal rocks

Hypabyssal rhyolite of Clear Creek (late Oligocene)

Microtonalite (late Oligocene?)

Felsic plutons and dikes of Winfield Peak and Middle Mountain of Fridrich 

and others (1998) (middle Eocene)

Rhyolite dikes (Paleocene or Late Cretaceous)

Felsic porphyry intrusive (Paleocene or Late Cretaceous)

Proterozoic igneous and metamorphic rocks

Pegmatite (Mesoproterozoic and (or) Paleoproterozoic)

Monzogranite and quartz monzonite (Mesoproterozoic)

Monzogranite of Langhoff Gulch (Mesoproterozoic)

Strongly foliated phase

Granite of Granite (Mesoproterozoic)

Granitic gneiss (Paleoproterozoic)

Leucogranite gneiss (Paleoproterozoic)

Biotite gneiss (Paleoproterozoic)

Hornblende gneiss and amphibolite (Paleoproterozoic)

Gabbro (Paleoproterozoic)

pt

Qb

Qva

Qopy

Qopo

Qoby

Qobo

Qoey

Qoeo

Qsw

Qac

Qf

Qta

Qc

Qls

Qrg

Qtpy

Qtpo

Qtb

Qte

Nd

va

dt

Kr

Ki

YXp

Ygr

Ygl

Yglf

Ygrg

Xgg

Xlg

Xb

Xhg

Xgb

af

mt

rc

wf

CORRELATION OF MAP UNITS

SURFICIAL DEPOSITS

Manmade

deposits

Lacustrine

deposits

Alluvial

deposits

Alluvial and

mass-movement

deposits

Mass-movement

deposits

Glacial

deposits

Holocene

Pleistocene

Neogene

Paleogene

TERTIARY

CRETACEOUS

MESOPROTEROZOIC

PALEOPROTEROZOIC

QUATERNARY

BEDROCK UNITS

af pt Qb mt

Qva

Qopy

?

? ? ???

Qopo

Qoby

Qobo

Qoey

Qoeo

Qsw

Qac Qf Qta Qc Qls

Qtpy

Qtpo

Qtb

Qte

Nd

va rc dt

wf

Kr Ki

YXp

Ygr

Ygl

Ygrg

Xgg Xlg Xb Xhg Xgb

Unconformity Unconformity

Volcanic

rocks

Hypabyssal

rocks

Post-volcanic

sediments

Proterozoic igneous

and metamorphic rocks

Pliocene

Miocene

Oligocene

Eocene

Paleocene

Late Cretaceous

?

?

?

Unconformity

Unconformity

Yglf

Qrg

?

?

EXPLANATION

80

Contact—Dashed where approximately located 

Fault, type unspecified—Dashed where approximately located; dotted where 

concealed beneath surficial deposits

Normal fault—Dashed where approximately located; short-dashed where inferred; 

dotted where concealed beneath surficial deposits; bar-and-ball symbol on 

apparent downthrown side; traces of inferred faults were identified from lidar 

imagery

Shoreline—Observed on lidar imagery

Fluvial scarp—Observed on lidar imagery; hachures are on riser between lower and 

higher surfaces and point downslope

Landslide scarp—Observed on lidar imagery and NAIP imagery; lower limit of 

hachures are on or near base of scarp. Prominent upslope facing scarps 

(sackungen) locally formed on the large landslide deposits derived from 

Proterozoic bedrock on the north side of Clear Creek near the southwest corner 

of the map area 

Toe of inactive solifluction deposits—Observed on NAIP imagery; sawteeth pattern 

is on the upslope side. Solifluction deposits were formed by downslope flowage 

of surficial material in the large alpine area near the head of Lost Canyon north 

of Clear Creek. Approximately located 

Shear zone—Marked by ductile deformation fabric in Proterozoic rocks 

Crest line of moraine—Observed on lidar imagery and NAIP imagery

Lineament—Observed on lidar imagery and NAIP imagery. Linear features locally 

may coincide with zones of fracturing in Proterozoic bedrock, tabular intrusive 

bodies, or linear mass-movement deposits

Inclined bedding—Showing strike and dip

Fault attitude—Showing fault dip

Inclined foliation—Showing strike and dip. Measurements of inclined foliation in 

areas of Quaternary surficial deposits (units Qc, Qac, and Qopy?) were made 

on Proterozoic bedrock outcrops that are too small to show at map scale

Vertical foliation—Showing strike

Mineral lineation—Showing bearing and plunge, depicted by an arrowhead

Sample—Location and isotopic ages of bedrock (see table 3 in pamphlet) 

Qsw/Nd

Qc/Nd

80

10

65

GR11–725

42.25 ± 0.13 Ma

Index. Hillshade map showing map area 

and adjacent USGS 7.5' quadrangles. 

Map names are in yellow.

1Colorado Geological Survey, McCalpin 

and others (2012)

2USGS Scientific Investigations Map 

3294, Shroba and others (2014)

3USGS Scientific Investigations Map 

3271, Bohannon and Ruleman (2013) 

4USGS Miscellaneous Field Studies Map 

555, Tweto (1974)

5USGS Scientific Investigations Map 

3267, Kellogg and others (2013)

EXPLANATION

24 Major roads

82

82

300

24

24

Mount Massive Leadville South1

Mount Sherman3,4

Mount Elbert Granite2 South Peak4

Winfield Winfield Mount Harvard Mount Harvard Mount Harvard Harvard Lakes Harvard Lakes5

Shaded relief was derived from U.S. Geological Survey National Elevation Dataset (NED, 

http://ned.usgs.gov/) with 10-m resolution elevation data.

0 10 KILOMETERS

0 10 MILES

5

5

106°30' 106°22'30" 106°15' 106°07'30"

39°15'

39°07'30"

39°00'

38°52'30"

U.S. highway route marker

State highway route maker

Area covered by lidar imagery

Area not 

covered

by lidar

imagery

106°22'30"

39°07'30"

39°00'

106°15'

Figure 1. Area of Granite 7.5' 

quadrangle covered by light 

detection and ranging (lidar) 

imagery shown in yellow. This 

imagery, along with field observations, was used to map surficial 

deposits, Dry Union Formation, 

inferred faults, lineaments, fluvial 

scarps, and other geomorphic 

features. Area in blue indicates 

region of quadrangle not covered 

by lidar imagery data that was 

interpreted with the aid of National 

Agriculture Imagery Program 

(NAIP) imagery.

Figure 2. Geographic setting of the Granite 7.5' quadrangle. Quadrangle boundary 

shown by yellow rectangle. Channels of Arkansas River and East Fork of 

Arkansas River are approximately located.

EXPLANATION

Major roads

River

Sample—Location of dated 

volcanic ash deposits

24

82

Bishop ash

U.S. highway route marker

State highway route maker

Location of towns

106°22'30" 106°15' 106°07'30" 106°00'

39°15'

39°07'30"

39°00'

38°52'30"

38°45'

38°37'30"

38°30'

82

285

50

24

291

285

24

285

9

9

24

50

Granite

South 

Mosquito Range Mosquito Range Mosquito Range Mosquito Range Mosquito Range

Sawatch Range Sawatch Range Sawatch Range Sawatch Range Sawatch Range

Park

Granite

Balltown

Leadville

Buena Vista

Nathrop

Salida

Bishop ash

Lava Creek B ash

Shaded relief was derived from U.S. Geological Survey National Elevation Dataset (NED, 

http://ned.usgs.gov/) with 10-m resolution elevation data.

Twin Lakes

Arkansas 

River

East Fork

Arkansas River

0 10 KILOMETERS

5 10 MILES

5

0

Salida

Photograph 1. View toward the west of the Twin Lakes 

area and the adjacent Sawatch Range accented by fall 

colors. Photograph by K.S. Kellogg, September 12, 2012.

Photograph 3. Close-up view of unoxidized till of Pinedale age, 

younger unit (Qtpy), exposed in southwest-facing road cut, about 

2.1 km northeast of the north end of the Twin Lakes dam. 

Hammer handle is 28 cm long. Photograph by R.R. Shroba, 

September 14, 2012. 

Photograph 2. View toward the west of fluvial sediments of the 

Dry Union Formation (Nd) exposed in an east-facing stream cut, 

about 1 km west of the Granite Cemetery. Sediments are 

composed chiefly of silty sand above cobbly pebble gravel. 

Trekking pole near base of photograph is 1.1 m long, and is 

roughly perpendicular to bedding. Photograph by R.R. Shroba, 

October 15, 2011.

Photograph 4. View toward southwest of snow-capped peaks of the Sawatch Range near 

western boundary of the Granite 7.5' quadrangle. The high, flat-topped summit on the skyline, 

in the western one-quarter of the photograph, is Mount Hope (4,240 m; 13,933 ft). Photograph 

by R.R. Shroba, October 12, 2011.

Photograph 3. Close-up view of unoxidized till of Pinedale age, 

P

a

c

Photograph 4. View toward southwest of snow-capped peaks of the Sawatch Range near

Photograph 2. View toward the west of fluvial sediments of the

CONVERSION FACTORS

Multiply By To obtain

inches (in.)

inches (in.)

0.3937

0.03937

3.281 feet (ft)

0.6214 mile (mi)

0.3861 

millimeters (mm)

centimeters (cm)

meters (m)

kilometers (km)

square kilometer (km2

)

cubic meter per second (m3

/s) 

square mile (mi2

)

35.31 cubic foot per second (ft3

/s)

COLORADO

QUADRANGLE LOCATION APPROXIMATE MEAN

DECLINATION, 2013 TRUE NORTH

MAGNETIC NORTH

Base from U.S. Geological Survey, Granite, Colo., 1:24,000, 1994 9°

North American Datum of 1927 (NAD 27) 

Projection and 10,000-foot ticks: Colorado coordinate system, central zone 

(Lambert conformal conic)

1000-meter Universal Transverse Mercator ticks, zone 13

R.R. Shroba mapped Quaternary surficial deposits and Neogene sediments 

during 2008–2012, and did reconnaissance mapping and soils research in and 

near the Granite 7.5' quadrangle between 1972–1974 during graduate studies 

at the University of Colorado at Boulder. K.S. Kellogg mapped the Paleogene 

and older rocks in the quadrangle during 2010–2011. T.R. Brandt prepared the 

digital topographic base map, digital compilation, and GIS database of the 

geologic map. He also generated slope and shaded-relief scenes from lidar 

data, which were used to interpret geologic, geomorphic, and shoreline 

features.

Publishing support provided by: 

Denver Publishing Service Center

Edit and digital layout by C.F. Chan

Manuscript approved for publication March 21, 2014

To learn about the USGS and its information products visit

http://www.usgs.gov/ 

1-888-ASK-USGS

This report is available at:

http://pubs.usgs.gov/sim/3294

Suggested citation: Shroba, R.R., Kellogg, K.S., and Brandt, T.R., 2014, Geologic 

map of the Granite 7.5' quadrangle, Lake and Chaffee Counties, Colorado: U.S. 

Geological Survey Scientific Investigations Map 3294, 31 p., 1 sheet, scale 

1:24,000, http://dx.doi.org/10.3133/sim3294. 

ISSN 2329-132X (online)

http://dx.doi.10.3133/sim3294

Geologic Map of the Granite 7.5' Quadrangle, Lake and Chaffee Counties, Colorado

By

Ralph R. Shroba, Karl S. Kellogg, and Theodore R. Brandt

2014

Any use of trade, firm, or product names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this information product, for the most part, is in the public domain, it also may 

contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items 

must be secured from the copyright owner.

This database, identified as SIM 3294, has been approved for release and publication by the 

U.S. Geological Survey (USGS). Although this database has been subjected to rigorous review 

and is substantially complete, the USGS reserves the right to revise the data pursuant to 

further analysis and review. Furthermore, it is released on condition that neither the USGS nor 

the U.S. Government may be held liable for any damages resulting from its authorized or 

unauthorized use.

For more information concerning this publication, contact:

Center Director, USGS Geosciences and Environmental Change Science Center

Box 25046, Mail Stop 980

Denver, CO 80225

(303) 236-5344

Or visit the Geosciences and Environmental Change Science Center Web site at:

http://gec.cr.usgs.gov/

Lidar imagery generated from lidar data sourced by the U.S. Geological 

Survey. Area not covered by lidar has shaded relief from U.S. Geological 

Survey National Elevation Dataset (NED).

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Map 3294

Pamphlet accompanies map

1 1/ 2 0 1 MILE

SCALE 1: 24 000

1000 1000 0 2000 3000 4000 5000 6000 7000 FEET

1 0 1/ 2 1 KILOMETER