Landslides and rockfalls are potential hazards in areas that have steep topography. Most Missouri bluffs are fairly stable, but some can pose problems. The most hazardous are bluffs that contain thick beds of sandstone or carbonate rock, underlain by shale. The shale will often preferentially weather to form a re-entrant beneath the harder rock, leaving large pieces of cantilevered rock. Rocks that fall from bluffs typically collect at their base. Geologists examine the bases of bluffs to estimate what size rockfalls they can produce.
Steep slopes of loess, till, thick colluvium, alluvium and shale can be prone to landsliding. The problem is often exacerbated by seasonally high water tables. In general, the higher and steeper the slope, the further and faster the slide will move. Look for scallop-shaped scars along the slope and uneven or undulating ground at the base of slopes. Modifying slope toes can cause problems, even on slopes that appear stable. Care should be taken when modifying slopes and changing natural water courses in unconsolidated materials.
Studies and Projects
Geologic Mapping
The department partnered with the Missouri State Emergency Management Agency (SEMA) to create two series of maps to assist Missourians in their planning and response to a disaster, Geologic Hazards Map Series and Debris Management Map Series. The Geologic Hazards map series depicts areas where natural conditions exist with the potential for landslides, collapse (sinkhole and mining related) and liquefaction (wet, loosely packed soil can act like a liquid during strong ground shaking). These maps can help emergency managers in pre-planning or responding to a natural disaster or simply as a guide to regional geologic hazard potential. There are nine regional maps, which correlate to the nine SEMA regions, and 18 1:24,000 scale maps in the St. Louis area. The maps can be viewed or downloaded as PDF maps through the Geologic Mapping for Natural Disasters map viewer. Click the Geologic Hazards button at the bottom of the map viewer window.
Historic Landslides Mapping
The department's Missouri Geological Survey was awarded a USGS grant in July 2026 to identify and map the location of historic landslides in southeastern Missouri. The study area will be along the Interstate 55 corridor through the Benton Hills area of Scott and Cape Girardeau counties. The department hopes to release maps and other data generated through the study to the public in the fall of 2027. More information is available in the Missouri Geological Survey awarded USGS grant to study landslides news release.