GEOLEX

Summary of Citation: Broadway

Publication:
Scott, G.R., 1960, Subdivision of the Quaternary alluvium east
   of the Front Range near Denver, Colorado: Geological Society
   of America Bulletin, v. 71, no. 10, p. 1541-1544

Usage in Publication:
Broadway alluvium*

Modifications:	Geologic Province:	Dominant Lithology:
Named	Denver basin	Sand

Summary:
Named for Broadway Avenue on Broadway terrace which lies 25 ft above the South Platte River, Denver, Denver Co, CO in the Denver basin. Type locality is a gravel pit in SEl/4 sec 30, T2S, R67W. Consists of 12 to 15 ft of reddish-brown, fine- to coarse-grained sand and some pebbles. Is younger than Louviers alluvium (new); is older than pre-Piney Creek alluvium. Is underlain by alluvium of two ages. Is overlain by a sheet of later alluvium. Thought to be of late Wisconsin, Pleistocene age.

Summary of Citation: Broadway

Publication:
Scott, G.R., 1962, Geology of the Littleton quadrangle, Jefferson,
   Douglas, and Arapahoe Counties, Colorado, IN Contributions
   to general geology, 1960: U.S. Geological Survey Bulletin,
   1121-L, p. L1-L53

Usage in Publication:
Broadway alluvium*

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:24k (Littleton quad, Arapahoe, Douglas, and Jefferson Cos, CO)	Denver basin	Sand

Summary:
Is upper Wisconsin (Pleistocene) formation mapped in west Arapahoe and northwest Douglas Cos, CO (Denver basin). Older than "pre-Piney Creek alluvium" map unit (lower Recent [Holocene]); younger than "younger loess" map unit (lower Wisconsin). Consists of about 25 ft of pebbly sand in a well-formed terrace along South Platte River and Plum Creek; is almost entirely confined to east side of streams. Terrace is about 25 ft above stream level but is poorly preserved due to stream changes and erosion in Recent time. Alluvium is composed of grayish-brown or moderate yellowish-brown well-stratified humic pebbly sand near sides of valleys, but grades into reddish-brown well-washed coarse pebbly sand near center of valley. Pebbles are composed mainly of granite, quartz, ironstone, feldspar, welded tuff. Finer alluvium is well stratified, but coarser alluvium is crudely stratified.

Summary of Citation: Broadway

Publication:
Scott, G.R., 1963, Quaternary geology and geomorphic history of
   the Kassler quadrangle, Colorado, IN Geology of the Kassler
   quadrangle, Jefferson and Douglas Counties, Colorado: U.S.
   Geological Survey Professional Paper, 421-A, p. A1-A70, (incl.
   geologic map, scale 1:24,000)

Usage in Publication:
Broadway alluvium*

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:24k (Kassler quad, Douglas and Jefferson Cos, CO)	Denver basin	Sand Pebbles

Summary:
Is Pleistocene formation mapped in northwestern Douglas Co, CO (Denver basin). On map explanation Broadway is shown to be younger than younger loess unit and older than pre-Piney Creek alluvium. Broadway is described (p. 38) as a uniform coarse-grained sand near center of Plum Creek channel (in northeasternmost corner of quad), but grades into silty humic coarse-grained sand near east edge of channel. Uniform sand is reddish brown and clean and contains subangular to subrounded pebbles, most of which are less than 1 in. in diameter. Humic silty sand is grayish brown. Measured section. Thickness is estimated to be about 25 ft. Age considered to be late Wisconsin (Pleistocene) because: (1) upper part of gravel capping Broadway terrace contains late Pleistocene fossils and is considered late Wisconsin, (2) Broadway alluvium was first alluvium deposited after early Wisconsin Louviers alluvium, and (3) it is older than pre-Piney Creek alluvium.

Summary of Citation: Broadway

Publication:
Scott, G.R., 1972, Geologic map of the Morrison quadrangle,
   Jefferson County, Colorado: U.S. Geological Survey Miscellaneous
   Investigations Series Map, I-790-A, 1 sheet, scale 1:24,000

Usage in Publication:
Broadway Alluvium*

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:24k (Morrison quad, Jefferson Co, CO)	Denver basin	Alluvium

Summary:
Is Pleistocene (Pinedale Glaciation) alluvium mapped in Jefferson Co, CO (Denver basin). Map unit described as yellowish-orange to light-brown, sandy to clayey alluvium along small intermittent streams or cobbly alluvium along major streams. Largest exposure in Green Mountain Village area, east-central part of quad; a few smaller exposures occur along hogback. Contains fossil mollusks. On Correlation of Map Units is shown to unconformably overlie Louviers Alluvium (Pleistocene--Bull Lake Glaciation) and to unconformably underlie eolian sand unit (lower Holocene and upper part of Pinedale Glaciation). Correlates in part with upper Holocene to Pleistocene landslide and colluvium units. Thickness probably about 25 ft. Brown soil of early Holocene age (Altithermal) in upper part. Terrace is 25-40 ft above modern streams.

Summary of Citation: Broadway

Publication:
Maberry, J.O. and Lindvall, R.M., 1972, Geologic map of the
   Parker quadrangle, Arapahoe and Douglas Counties, Colorado:
   U.S. Geological Survey Miscellaneous Investigations Series
   Map, I-770-A, 1 sheet, scale

Usage in Publication:
Broadway Alluvium*

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:24k (Parker quad, Arapahoe and Douglas Cos, CO)	Denver basin	Sand Clay

Summary:
Is Pleistocene formation mapped in southwestern Arapahoe and northern Douglas Cos, CO (Denver basin). Conformably overlies lower part (younger part) of Louviers Alluvium (Pleistocene); younger than eolian sand unit (Pleistocene and Holocene); lower part correlates with upper part of loess unit (Pleistocene). Unit described as dark-yellowish-brown to light-brown fine to coarse pebbly sand composed of quartz and feldspar grains, with interbedded lenses of clay. Occurs as terrace surfaces 10-30 ft above principal streams. Up to 30 ft thick.

Summary of Citation: Broadway

Publication:
Machette, M.N., 1977, Geologic map of the Lafayette quadrangle,
   Adams, Boulder, and Jefferson Counties, Colorado: U.S.
   Geological Survey Geologic Quadrangle Map, GQ-1392, 1 sheet,
   scale 1:24,000

Usage in Publication:
Broadway Alluvium*

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:24k (Lafayette quad, Adams Boulder, and Jefferson Cos, CO)	Denver basin	Sand Silt Gravel

Summary:
Is Pleistocene (Pinedale age) formation mapped in southeastern Boulder, northeastern Jefferson, and northwestern Adams Cos, CO (Denver basin). Unconformably overlies Louviers Alluvium (Pleistocene, Pinedale-Bull Lake interglaciation and Bull Lake glaciation); unconformably underlies Piney Creek Alluvium (Holocene). Unit described as light-gray-brown to light-brown moderately well sorted fine sand and silt; minor clayey gravel lenses near base. Alluvium is cross-bedded and generally finer grained upward in deposit. Forms terraces 3-4 m above modern flood plain of Big Dry Creek. Upper part has weakly developed zonal soil with poorly developed Cca (calcium carbonate-enriched) horizon. Soil profile shown. Thickness 5-6 m along Big Dry Creek; more than 6 m along Coal Creek at north edge of quad. Radiocarbon date of charcoal from near base of unit is greater than 38,440 yrs B.P.

Summary of Citation: Broadway

Publication:
Maberry, J.O. and Lindvall, R.M., 1977, Geologic map of the
   Highlands Ranch quadrangle, Arapahoe and Douglas Counties,
   Colorado: U.S. Geological Survey Geologic Quadrangle Map,
   GQ-1413, 1 sheet, scale 1:24,000

Usage in Publication:
Broadway Alluvium*

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:24k (Highlands Ranch quad, Arapahoe and Douglas Cos, CO)	Denver basin	Silt Sand Gravel

Summary:
Is Pleistocene formation mapped in southwestern Arapahoe and northern Douglas Cos, CO (Denver basin). Is younger than Slocum Alluvium (Pleistocene); conformably underlies Piney Creek Alluvium (Holocene); shown on Correlation of Map Units to be equivalent to lower part of colluvium, eolian sand, and loess units (Pleistocene and Holocene). Unit described as tan to light-brown, generally well-stratified silt, sand, and gravel; contains abundant plant debris. Forms low terraces about 10-25 ft above modern streams; most prominently exposed along Big Dry Creek in central part of quad. [Thickness not given.]

Summary of Citation: Broadway

Publication:
Lindvall, R.M., 1978, Geologic map of the Fort Logan quadrangle,
   Jefferson, Denver, and Arapahoe Counties, Colorado: U.S.
   Geological Survey Geologic Quadrangle Map, GQ-1427, 1 sheet,
   scale 1:24,000

Usage in Publication:
Broadway Alluvium*

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:24k (Fort Logan quad, Arapahoe, Denver, and Jefferson Cos, CO)	Denver basin	Sand Gravel

Summary:
Is Pleistocene formation mapped in western Denver and eastern Jefferson Cos, CO (Denver basin). On Correlation of Map Units, Broadway is shown to unconformably overlie Louviers Alluvium (Pleistocene) and to unconformably underlie eolian sand unit (Pleistocene and Holocene). Correlates in part with loess and colluvium units (both units are Pleistocene and Holocene). Unit described as pink to light-brown, generally well-stratified sand and gravel, in well-formed terraces along South Platte River and Lakewood and McIntyre Gulches. Alluvium on west side of South Platte River and its tributaries generally is fine sand and silt. Upper surfaces of terrace deposits are about 25-30 ft above modern major steams. Mapped in northern half and southeastern part of quad. Engineering properties discussed. Up to 30 ft thick.

Summary of Citation: Broadway

Publication:
Lindvall, R.M., 1979, Geologic Map of the Arvada quadrangle,
   Adams, Denver, and Jefferson Counties, Colorado: U.S. Geological
   Survey Geologic Quadrangle Map, GQ-1453, 1 sheet, scale
   1:24,000

Usage in Publication:
Broadway Alluvium*

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:24k (Arvada quad, Adams, Denver, and Jefferson Cos, CO)	Denver basin	Sand Gravel Silt

Summary:
Is Pleistocene formation mapped in northeastern Jefferson Co, CO (Denver basin). On Correlation of Map Units, Broadway is shown to unconformably overlie Louviers Alluvium (Pleistocene) and to unconformably underlie eolian sand unit (Pleistocene and Holocene); correlates in part with Pleistocene and Holocene colluvium and loess units. Broadway is described as pink to light-brown, generally well stratified sand and gravel in well-defined terraces. Upper 2-3 ft commonly a clayey to pebbly silt. Occurs in small area on western edge of quad south of Leyden Creek. Engineering properties discussed. Is up to 15 ft thick.

Summary of Citation: Broadway

Publication:
Lindvall, R.M., 1980, Geologic map of the Commerce City quadrangle,
   Adams and Denver Counties, Colorado: U.S. Geological Survey
   Geologic Quadrangle Map, GQ-1541, 1 sheet, scale 1:24,000

Usage in Publication:
Broadway Alluvium*

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:24k (Commerce City quad, Adams and Denver Cos, CO)	Denver basin	Gravel Sand Silt

Summary:
Is Pleistocene formation mapped in northern Denver and western Adams Cos, CO (Denver basin). Unconformably overlies Louviers Alluvium (Pleistocene); unconformably underlies eolian sand unit (Pleistocene and Holocene). Correlates in part with loess and colluvium units (both Pleistocene and Holocene). Unit described as pink to light-brown, generally well stratified sand and gravel. Upper 2-3 ft commonly is a clayey to pebbly silt. Occurs in well-defined terraces on east side of South Platte River valley. Engineering properties discussed. Is up to 15 ft thick.

Summary of Citation: Broadway

Publication:
Shroba, R.R., 1980, Geologic map and physical properties of the
   surficial and bedrock units of the Englewood quadrangle,
   Denver, Arapahoe, and Adams Counties, Colorado: U.S. Geological
   Survey Geologic Quadrangle Map, GQ-1524, 1 sheet, scale
   1:24,000, Supersedes U.S. Geological Survey Open-File Report
   OF-77-862.

Usage in Publication:
Broadway Alluvium*

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:24k (Englewood quad, Adams, Arapahoe, and Denver Cos, CO)	Denver basin	Sand Silt

Summary:
Is Pleistocene formation mapped in southwestern Arapahoe and eastern Denver Cos, CO (Denver basin). Unconformably overlies Louviers Alluvium (Pleistocene); unconformably underlies Piney Creek Alluvium (upper Holocene) and undifferentiated alluvium unit (upper Holocene). Correlates in part with lowermost part of eolian sand unit (upper Pleistocene to upper Holocene) and part of colluvium unit (Pleistocene to Holocene). Unit described as light-brown, noncalcareous, clean to slightly silty pebbly sand interbedded with sandy silt to silty sand along South Platte River and silty pebbly sand interbedded with sandy silt along Cherry Creek. Slightly finer grained in upper meter. Forms terraces about 12-14 m above South Platte River, 6 m above Cherry Creek, and 5 m above Little Dry Creek. Partially to completely buried by eolian sand in places. Table of physical properties. Thickness is 6-9 m along South Platte River in Denver's central business district and probably less than 9 m along Cherry Creek and Little Dry Creek.