Geologic map of the Palisade Quadrangle, Mesa County, Colorado

This map has been prepared to provide the first detailed view of the Palisade
1:24,000-scale quadrangle. Previous geologic mapping that encompassed the map
area was at scales of 1:100,000 and 1: 250,000. The Palisade area is an
important agricultural region of Colorado, fruit orchards were first
established in the area in the late 19th century. In addition, the Palisade
quadrangle is undergoing rapid growth, as is the rest of the Grand Valley.
Because of this rapid growth, the recognition of geologic hazards is important.
The map depicts many surficial units associated with geologic hazards. The map
is accompanied by a separate leaflet containing a section on geologic hazards
(including landslides, piping, gullying, expansive soils, and flooding). A
table indicates what map units are susceptible to a given hazard. The map will
be of interest to town and county officials, land- use planners, as well as the
general public.

The Palisade 1:24,000 quadrangle is in Mesa County in western Colorado. Because
the map area is dominated by various surficial deposits, the map depicts 22
different Quaternary units. Two prominent river terraces are present in the
quadrangle containing gravels deposited by the Colorado River. The map area
contains many mass movement deposits. Extensive landslide deposits are present
along the eastern part of the quadrangle. These massive landslides originate on
the flanks of Grand Mesa, in the Green River and Wasatch Formations, and flow
west onto the Palisade quadrangle. In addition, large areas of the eastern and
southern parts of the map are covered by extensive pediment surfaces. These
pediment surfaces are underlain by debris flow deposits also originating from
Grand Mesa. Material in these deposits consists of mainly subangular basalt
cobbles and boulders and indicate that these debris flow deposits have traveled
as much as 10 km from their source area. The pediment surfaces have been
divided into 5 age classes based on their height above surrounding drainages.

Two common bedrock units in the map area are the Mancos Shale and the Mesaverde
Group both of Upper Cretaceous age. The Mancos shale is common in low lying
areas near the western map border. The Mesaverde Group forms prominent
sandstone cliffs in the north-central map area.

The map is accompanied by a separate pamphlet containing unit descriptions, a
section on geologic hazards (including landslides, piping, gullying, expansive
soils, and flooding), and a section on economic geology (including sand and
gravel, and coal). A table indicates what map units are susceptible to a given
hazard. Approximately twenty references are cited at the end of the report.

Map political location: Mesa County, Colorado

Compilation scale: 1:24,000

Geology mapped in 1996 and 1997