Field Geology 2009:
Exploring the Raton Basin and Southern
Rockies of Colorado,

Emporia State University
Susan W. Aber

Devil's Staircase dike in late Spring
One rock wall of the impressive swarm of dikes
that surround Spanish and Silver Peaks west of
Walsenberg, Colorado. Photo by J.S. Aber;
Photo date May 2006.

As we move our field geology course west, you can look at Colorado from a Kansas perspective! After leaving Kansas, we will drive through La Junta. At that point, we leave the ribbon of darker blue color, the Arkansas River Valley, and continue driving into the "cyan prairie," arriving left of Pueblo at the first mountain range. We will then navigate in the colored areas of green, yellow, brown, and white in south-central Colorado! As we are driving, you can be reading a suggested course textbook, Messages in Stone (

viewing Colorado from Kansas at
This is one of the many informative maps found on the Colorado Geologic Survey
website. The image was taken from

Navigating this Webpage

Physiographic Provinces Elevation and Geology Maps Maps of Specific Geologic Time Periods
Geologic Time Chart Geology Map Mashup References and Links
What about identifying rocks in my collection? Go to

Physiographic Provinces

Map taken from the Colorado Geological Survey
Spanish Peaks and Tinchera Peak are points of interest for field geology and are situated in the physiographic provinces of Raton Basin and Southern Rocky Mountains in south-central Colorado. Physiographic provinces categorize Colorado by overall landscape, vegetation, and physical geology. In these two provinces, elevations range from over 3,000 to over 14,000 feet; vegetation ranges from cholla cactus (Opuntia) to Colorado blue spruce (Picea pungens). The Raton Basin is a relatively flat plain that ramps up to the west and is distinguished by major igneous intrusive features such as East and West Spanish Peaks near La Veta. The Southern Rocky Mountains physiographic province varies greatly from steep, massive mountains such as Trinchera Peak near Cuchara to the large, high desert of the San Luis Valley where Alamosa is situated centrally.

A dramatic change in the landscape is highlighted in the shaded relief map below. The eastern two-fifths of the state is a relatively uninterrupted plain, while an abrupt change in elevation is obvious to the central and western parts of the state. Spanish Peaks rises 7,000 feet above the western Great Plains and are located at the extreme west edge of the Raton Basin province. It is easy to understand that one of the major rivers in Kansas has its headwaters near Leadville, over 10,000 feet in elevation; the Arkansas River exits Kansas at an elevation of just over 1,000 feet, on its way to the Mississippi River and Gulf of Mexico. According to Kammerer (1990), the Arkansas river is the sixth longest river in the United States, at 1,469 miles (

Elevation and Geology Maps

Although seven physiographic provinces are defined in Colorado, there are basically three topographic/geologic zones in the state. Topographically, the state is divided into Eastern Plains, Rocky Mountains, and Colorado Plateau. Geologically, the eastern plains and western plateau are composed of sedimentary rock whereas, the Rocky Mountain province is a complex assortment of igneous, metamorphic, and sedimentary rocks in approximate equal proportions (

The Raton Basin is known for the exposed rocks defining the Cretaceous-Tertiary boundary. The Raton Basin transitions into the Southern Rocky Mountains when we cross the Cretaceous Dakota Sandstone hogback into the Lower Permian. This is roughly the same age of rock we left over 500 miles behind in Chase County, Kansas (

general geologic map of Colorado
Colorado Geologic Map generalized-click for a larger view. Image taken
from To see greater detail,
This shaded relief map was taken from
For more information, see">

While it is difficult to get much useful information from the geologic map to the left, maps shown below will focus on specific geologic ages and features. The maps are positioned to begin with the youngest rocks at the top and older as you page down. Click on the images to see a larger verson and read more detail at the associated Colorado Geological Survey website.

Distribution Maps of Specific Geologic Time
Distribution of Wind Deposited Quaternary Rocks.
Image taken from
Distribution of Quaternary Rocks. Image taken from
Distribution of Late Neogene and Quaternary
Basalt Flows. Image taken from
Distribution of Tertiary Volcanics. Image taken from
Distribution of Tertiary Rocks. Image taken from
Distribution of Cretaceous Rocks. Image taken from
Distribution of Triassic and Jurassic Rocks.
Image taken from
Distribution of Pennsylvanian and Permian Rocks.
Image taken from
Distribution of Lower and Middle Paleozoic Rocks.
Image taken from
Distribution of Precambrian Rocks. Image taken from

Colorado Geologic Events by Time Period

A geologic time chart is shown below with annotation of Colorado geologic events (from

Geologic Map Mashups

While this is not our region of investigation, this is a tremendously valuable example of what can be done with geologic mapping today! This block diagram allows the viewer to see simultaneously surface and subsurface geology along with topographic information when a geologic map is draped over a digital elevation model and attached to the cross section profile. Want to see more?!!

This webpage provides ideas for information that may fit into the theme of your final report or merely make a topic clear. Links are given below for additional Colorado materials. Do not forget to cite and reference throughout your report. If you have any questions about good writing to avoid plagiarism, obtain the following resource:
Harris, R. A. (2005). Using sources effectively strengthening your writing and avoiding plagiarism (2nd ed). Los Angeles, CA: Pyrczak Publishing (

Reference and Weblinks of Interest

Kammerer, J.C. (2005). Largest rivers in the United States. U.S. Geological Survey, Department of the Interior, Water Fact Sheet, Open-File Report 87-242. Online at Retrieved June 6, 2009.

  • Geologic Mapping,
  • Messages in Stone-Colorado's Colorful Geology and
    Tourist Guide to Colorado Geology
  • Colorado State Symbols: Mineral, Gem, Rock, Fossil
  • Field Trips,
    . See the Dash with Dinosaurs and K-T Boundary Impact Layer of Southern Colorado,
  • Colorado Mineral Fact Sheet 2007
  • Photo Gallery,

  • Statewide Maps of Colorado,
  • Resources for Teachers,
  • Rock Talk - Molybdenum,
  • Rock Talk - Diamonds,
  • Rock Talk - Gold,
  • Rock Talk - Geology and Mining,
  • Rock Talk - Oil and Gas,
  • Energy Facts,
  • Geologic Hazards,
  • Earthquakes,
  • Caves in Colorado,
  • Colorado Mineral and Energy Industry Activities 2007,
  • Colorado Native Plants,
  • Vegetation Drought Response Map, June 2009,
  • Colorado Vegetation Classification Interactive Project (go to Map and begin!),
  • Abandoned Mines and Naturally Occurring Acid Rock Drainage on National Forest System Lands in Colorado,
  • Colorado's Ancient Trees,
  • Major Rivers,
  • Glaciers during the last Ice Age,
  • Major Tectonic and Geographic Features,
  • Late Cenozoic Fault & Fold Database, & Map Server,
  • Western Region Geography,
  • The National Map Viewer instructions,
  • National Geologic Map Database, USGS,
  • Return to Exploring the Flint Hills of Kansas,, or GO547 Field Geology course webpage,

    This page is associated with Earth Science and is primarily for the use and benefit of students enrolled at Emporia State University. For more information contact the course instructor, S. W. Aber, e-mail: Thanks for visiting! Last update: 6 June, 2009.

    copyright 2009 © Susan Ward Aber. All rights reserved.