Culturally Modified Trees (or CMTs) are trees that exhibit peels, ax cuts, delimbing, wood removal, and other cultural modifications. Numerous CMTs are found in the foothills and mountains of Colorado. Research has shown that these trees are artifacts reflecting cultural utilization of trees by Native Americans and other people from the seventeenth century through the early twentieth century.
Tree bark and bark-related substances are known to have been used for a variety of functions by Native Americans and other early historic peoples. The outer bark of trees was used to construct trays, baskets, and cradleboards, as well as roofs and walls of structures. Resin and pitch obtained from areas of a tree where the bark was peeled were used as adhesives and waterproofing agents for baskets and other objects. Wooden slabs pried from peeled areas on trees were used to construct saddle frames, cradleboards, and wooden tools. The inner bark, pitch, and sap were utilized medicinally as a poultice or drink for many types of disorders. The inner bark was also used by Native Americans as a delicacy or sweet food and as an emergency food in circumstances of starvation.
Types and Characteristics of CMTs
Types of scientifically recognized CMTs include witness/survey marker, delimbed, fence line, claim marker, trail marker/blazed, and peeled trees. These CMTs exhibit characteristics that differ from natural scarring by animals such as porcupine or bear, or scars created by lightning or ground fires.
Witness/survey marker trees were modified to delineate geographical locations. They are often associated with rock cairns (stacked stones) and metal sign-markers. Trees that were delimbed usually exhibit ax-cut limbs and were often located along trails or roads to enlarge a travel corridor or create open spaces for livestock. Fence-line trees were often peeled vertically to enable attachment of metal fencing. Claim marker trees usually exhibit a peeled area or shelf cut into a tree to place mining claim information or signs. Trail marker / blazed trees were modified with an ax or other sharp tool to delineate trails, roads, and other significant locations or objects along travel corridors. Peeled trees exhibit various-sized scars where bark was removed from the trunk of a tree.
Species of CMTs found in Colorado include cottonwood, ponderosa pine, Engelmann spruce, piñon pine, limber pine, lodgepole pine, Douglas fir, Rocky Mountain juniper, and bristlecone pine. CMTs are found at elevations from approximately 6,000 to 11,700 feet in Colorado. CMTs are often found along trails, travel corridors, mountain passes, within or near campsites, and in the vicinity of water sources such as springs, streams, and rivers.
CMTs that were peeled to obtain inner bark or other bark or tree substances are the most common type documented in Colorado. Although they can vary in size and shape, peeled CMTs usually exhibit an oval or rectangular-shaped scar with one or more points at the upper end where the bark was removed from the tree trunk. The lower end of the peeled area is usually located one to three feet above the ground and often exhibits a horizontal cut line with visible ax cut marks.
The peeled areas range from one-half inch to five feet in width. The lengths of the scars range from four inches to nine feet. The average-sized peeled area is approximately seventeen inches wide and four feet long. A study replicating the bark peeling process indicates that approximately one pound of inner bark would have been available from a peel this size. Nutritional analysis of inner bark from pine indicates that one pound contains approximately 600 calories, calcium, carbohydrates, protein, iron, Vitamin C, magnesium, and zinc.
Based on interviews with Native Americans in the 1950s, the bark-peeling process took place as follows: a tree was selected for peeling, and a small sample of outer and inner bark were removed from the tree and tested. If determined acceptable, a horizontal cut was made across the tree trunk with an ax or other sharp tool. A debarking stick (sharpened on the end like a chisel) was utilized to pry the outer bark from the tree trunk. The inner bark was then removed from the outer bark slabs with a scraper and the inner bark was eaten or saved for later use. Other bark/tree substances—such as pitch, sap, and wooden slabs—were also removed, if desired.
Historical evidence and ethnographic studies (descriptions of human cultures) suggest that Native Americans likely created most of the existing peeled CMTs in Colorado from the late 1600s to the early 1900s. Groups in Colorado that were known to have used bark and bark-related substances include the Ute, Apache, Navajo, and various Ancestral Puebloan peoples. Other groups that may have created CMTs in Colorado include early Hispano and white explorers, traders, trappers, and settlers.
CMTs can be dated through dendrochronological analysis (tree-ring dating). Tree-ring dating is important because it enables archaeologists to determine the actual year that a tree was modified, and in some cases, even the season. This information provides archaeologists with a very detailed picture of how a specific geographical area was used through time during the early historic time period. It can also suggest which groups of people may have created the CMTs and help determine why the trees were used.
Current Status and Significance of CMTs in Colorado
Culturally modified trees have been recorded as archaeological resources in Colorado for over thirty-five years but prior to that, many of these trees had been overlooked as significant cultural resources. Some were cut down during development, timber harvesting, or road-building projects. Other CMTs have been destroyed or damaged by forest fires, insects, or disease. Additional CMTs have reached their maximum lifespan of 400-600 years and have begun to die of natural causes.
The trees are important cultural resources to help understand past lifeways, especially regarding how Native Americans adapted and survived during the recent historic past in Colorado. Archaeologists and land managers are studying CMTS and consulting with Native Americans to learn more about them and determine how to protect and manage these unique cultural resources. In 2000 a group of over seventy-two ponderosa pine CMTs (Indian Grove), located at Great Sand Dunes National Park and Preserve, was listed on the National Register of Historic Places. Many additional CMTs have been documented, dated, interpreted to the public, protected, and preserved.