Cliffs

Photo of cliffs overlooking Ha Ha Tonka Spring

Cliffs are steep to vertical exposures of bedrock (or loess) 10 feet or more in height. Nine distinct cliff natural communities have been identified in Missouri, distinguished by rock type and by amount of moisture.

In Missouri, cliffs can reach as high as 550 vertical feet. Most cliffs occur through the following processes:

  • As an escarpment created by erosion or faulting, separating two fairly level or gently sloping surfaces
  • Above high-gradient streams and large river floodplains
  • As a part of karst landforms, including sinkholes and the chasms made by collapsed caves

Cliffs often include features such as rock shelters, shelter caves, and overhangs. In Missouri, many of our dry caves occur as openings in cliffs, evidence of where a spring outlet once occurred.

Talus slopes, a distinct type of natural community, often occur at the bases of cliffs, where rocks have broken off of the cliff face.

Cliff Architecture

A cliff is generally divided into three parts, amounting to top, bottom, and middle:

1. The cliff edge is a level or sloping plain at the top of a cliff, extending back from the cliff face. It is excessively drained and extremely dry. The soils are very thin. Vegetation amounts to stunted woodland or grassland types. Xeric (dry-loving) and drought-tolerant plants are common: winter annuals, mosses, and lichens, as well as perennial wildflowers and annual grasses.

2. The pediment is the base rock at the bottom of the cliff. Many plants thrive at the bases of cliffs, where they may receive relatively abundant water and may enjoy especially warm (south-facing) or cool (north-facing) microclimates. Often a talus community forms near the cliff base.

3. The cliff face is the precipitous section of rock between the top and bottom. There are virtually no soils on this part of a cliff. Soils accumulate only on ledges and shelves of the rock. The plants that eke out a living in the steep or vertical face tend to be long-lived perennial forms: trees, shrubs, vines, and ferns.

Bluffs

Although any cliff with a broad, steep face may be called a bluff, the term bluff refers to a high bank or bold headland with a broad, precipitous, sometimes rounded cliff face. Bluffs can overlook either a plain or a body of water, especially on the outside curve of a stream meander.

Roadcuts

As human-made habitats, rocky roadcuts cannot be considered the same as natural cliffs, even though they have steep, rocky faces and thin soils, and undergo the same types of natural processes (such as rock fragmenting from freezing and thawing, rapid rain runoff, hot exposures when facing south, etc.).

In addition to being human-made habitats, roadcuts occur next to roadways and railroads. Natural cliffs were produced by natural geological processes, often over millions of years, and they usually occur next to rivers and streams, forests, woodlands, and other biologically rich habitats. Of course, highways and railroads can skirt the edge of natural cliffs, too. Newer rock cuts can usually be identified by the vertical drill marks left by the blasting procedure.

Cliff Plants

Cliff vegetation is usually sparse. Plants associated with cliffs include trees, shrubs, vines, ferns, perennial wildflowers, lichens, liverworts, and mosses. The trees are often stunted and gnarled and can be hundreds of years old. Not counting lichens, liverworts, and mosses, the vegetation usually covers only about 10 percent of the surface area.

Plant composition varies a great deal by bedrock type, moisture (including amount of groundwater seepage), slope, aspect, temperature, and amount of shading.

Cliff Animals

Not many animals are strongly associated with cliffs, and few seem to be restricted to cliff habitat. Many nest in rocky crevices, beneath overhangs and rocks, and along cliff edges.

Notable cliff animals include the following:

  • Amphibians — can occur on wet, moist, north-facing cliffs, including several species of lungless salamanders (family Plethodontidae) and pickerel frogs
  • Reptiles — usually found on dry, warm cliffs, including prairie lizards, five-lined skinks, rough greensnakes, and timber rattlesnakes
  • Birds — turkey vulture, eastern phoebe, American kestrel, northern rough-winged swallow, cliff swallow, and barn swallow. The Giant Canada goose subspecies historically nested on cliff faces, and so did the peregrine falcon (the latter now mostly occurs on the cliff-like surfaces of skyscrapers in big cities, where it has been successfully introduced, while efforts to reestablish it in its native cliff habitat have failed)
  • Mammals — eastern woodrat
  • Invertebrates — many groups of invertebrates occur, including snails, spiders, insects, centipedes, millipedes, and more. Among spiders, the funnel-web and aerial web spiders are especially notable. Paper wasps overwinter in crevices of cliffs.

Several animals are generalists and can live in many habitats — mice, for example. For these animals, a cliff represents a “predator-free” zone where they can avoid their enemies. Black ratsnakes, however, may frequent the bases of cliffs and prey on the mice, as well as any accessible bird nests attached to the cliff face.

Nine Types of Cliff Communities

Missouri's nine distinct types of cliff natural communities are named and defined in terms of moisture (dry or moist) and parent substrate (rock type). Sometimes a single cliff face can include different types of rocks (and associated moisture patterns).

  1. Dry limestone/dolomite cliff
  2. Moist limestone/dolomite cliff
  3. Dry chert cliff
  4. Moist chert cliff
  5. Dry sandstone cliff
  6. Moist sandstone cliff
  7. Dry igneous cliff
  8. Moist igneous cliff
  9. Unconsolidated cliff

Eight of the nine types exist in dry/moist pairs, occurring in the same geologic regions and differing only by aspect. The dry/moist pairs are combined below.

1 and 2. Limestone/Dolomite Cliffs

In general, dry cliff natural communities face south and west and are hotter and drier, and the moist ones face north and east and are cooler and wetter. Predictably, the dry cliffs of each pair have many lichens and other drought-adapted species, and the moist cliffs of each pair have many mosses, ferns, and other plants that love cool, moist locations. At their highest extensions, moist cliff habitats tend to turn into dry cliff types, due to drying conditions.

Many of Missouri's moist cliffs are home to unusual glacial relict plants, which exist in these habitats far south of where they usually occur today. They are survivors from a time of cooler temperatures, when their species had a broader range than today. As the climate warmed after the glaciers retreated, these boreal plants disappeared from the southern part of their range — except for the survivor populations in these cool, moist cliff locations. Some glacial relict plants in Missouri associated with cool, moist cliffs are red-berried elderberry, northern bedstraw, harebell, and amethyst shooting star.

Generally associated with large streams, these cliffs can be up to 200 feet high. The thin soils range from slightly acidic to moderately alkaline. Limestone/dolomite cliffs are found nearly statewide but are especially prominent in the Ozark Highlands and along the Mississippi River in northeast Missouri.

Representative Limestone /Dolomite Cliffs

  • Grand Bluffs Natural Area
  • Vilander Bluff Natural Area
  • Jam Up Bluff and Angel Ridge Bluff in the Jacks Fork Natural Area
  • Cardareva Bluff Natural Area
  • Carman Springs Natural Area
  • Barn Hollow Natural Area

3 and 4. Chert Cliffs

Often occurring along streams or rock ledges in valleys, often as a series of irregular rock terraces and ledges, chert cliffs can be 80 feet in height. The thin soils range from extremely acidic to moderately acidic. Chert cliffs are generally restricted to the Springfield Plain of southwestern Missouri, especially along Shoal and Turkey creeks. They also occur, to a much more limited extent, along small streams and ravines in Boone and Callaway counties in Central Missouri.

Chert cliff communities are rare and should be protected in Missouri.

Representative Chert Cliff Sites

  • Earthquake Hollow Conservation Area
  • Wildcat Glade Natural Area
  • Cowards Hollow Natural Area

5 and 6. Sandstone Cliffs

Occurring in deeply dissected hills, and in many places shelters or sandstone overhangs develop, sandstone cliffs can be up to 100 feet high. Where they can collect, the thin soils range from very strongly acidic to moderately acidic. Sandstone cliffs occur locally in the Ozark border, the Mississippi River hills, the Gasconade River hills, and the Springfield Plain. Sandstone overhangs are most developed in the Ozark border.

Representative Sandstone Cliff Sites

  • Hawn State Park
  • Hickory Canyons Natural Area
  • Pickle Springs Natural Area
  • Rocky Hollow Natural Area
  • Buzzard Bluff, along the Sac River in St. Clair County
  • Graham Cave Glades Natural Area

7 and 8. Igneous Cliffs

Igneous cliffs occur on knobs and mountains, often in a series of irregular rock terraces and ledges. The thin soils range from very strongly acidic to moderately acidic. Igneous cliffs are restricted to the St. Francois knobs and basins and Current River hills, with a few examples in the Lamotte Basin in Ste. Genevieve County.

Representative Igneous Cliff Sites

  • Johnson’s Shut-Ins Natural Area
  • Prairie Hollow Gorge Natural Area
  • St. Francois Mountains Natural Area
  • Royal Gorge Natural Area
  • Mill Mountain Natural Area
  • Mudlick Mountain Natural Area

9. Unconsolidated Cliffs

These cliffs are not separated into separate dry and moist communities. They occur in moderately steep to vertical slopes of deeply cut ravines or valleys, in sandy and/or gravelly bluffs, or along the crests of loess-capped limestone/dolomite cliffs along large rivers. The parent materials are unconsolidated glacial till, gravel, loess, or shale. Due to stream or riverbank cutting or seepage, these materials erode and slump into steep cliff surfaces. The soils are poorly developed and range from slightly acidic to moderately alkaline. Unconsolidated cliffs occur scattered along major streams and rivers of the glaciated plains of northern Missouri, in the Ozark border, along the Mississippi River, and in Crowley’s Ridge in the Bootheel.

Representative Unconsolidated Cliff Sites

  • Pelican Island Bluffs, in St. Louis County
  • The loess badlands of Howard County
  • Wild Stallion Creek Bluff, in Clark County
  • Battle of Athens State Historic Site, in Clark County
  • Star School Hill Prairie Natural Area
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Tree-lined road on Ashe-Juniper
Stone
Ashe Juniper Natural Area is located in Stone County, about 8 miles east of Blue Eye, Missouri.
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view from Barn Hollow
Texas
Barn Hollow Conservation Area is located in Texas County, approximately three miles north of Mo
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View from trail at Clifty Creek Natural Area, autumn
Maries
Clifty Creek Conservation Area and Clifty Creek Natural Area are adjacent to one another and co
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Illustration of eastern red cedar stem, leaves, and fruits.
Species Types
Scientific Name
Juniperus virginiana
Description
By far the most common native conifer in the state, eastern red cedar is useful for its aromatic, red wood and beloved for its greenery, its resinous blue “berries,” and the spicy odor it lends the outdoors.
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Illustration of shortleaf pine needles, twig, cones.
Species Types
Scientific Name
Pinus echinata
Description
Existing in thousands of acres of nearly pure stands, shortleaf pine was once the dominant tree in much of the Missouri Ozarks. Today, Missouri’s only native pine tree is recovering from the extensive logging that had exhausted its old-growth stands by the 1920s.
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Illustration of post oak leaf.
Species Types
Scientific Name
Quercus stellata
Description
Post oak has long been favored for fence posts and was valued by American pioneers. It has distinctive cross- or ghost-shaped leaves. It grows in rocky upland woodlands and in flatwoods on broad ridges.
Media
Illustration of chinkapin oak leaf.
Species Types
Scientific Name
Quercus muehlenbergii
Description
Chinkapin oak is fairly easy to identify because of its distinctively toothed leaves. Look for it growing in rocky soils derived from limestone or dolomite on bluffs and in upland woods, and in floodplain forests and lower slopes along streams.
Media
Photo of smooth sumac.
Species Types
Scientific Name
Rhus spp.
Description
Sumacs are shrubs or small trees that often form colonies from their creeping, branched roots. The foliage usually turns brilliant shades of red in early autumn. The clusters of berrylike fruits are red.
Media
Illustration of poison ivy leaves, flowers, fruits.
Species Types
Scientific Name
Toxicodendron radicans
Description
Poison ivy is a toxic plant that contains an oil in all its parts that, if you come into contact with it, can cause an intense skin reaction. Learn to recognize it, and sidestep it on your outings.
Media
Illustration of summer grape leaves, flowers, fruit
Species Types
Scientific Name
Vitis aestivalis
Description
Summer grape is a vigorous, woody, wild grapevine climbing to a height of 35 feet. It grows mostly in the southern two-thirds of Missouri, often in drier situations than many other grape species.
Media
Illustration of virginia creeper leaves, stem, flowers, fruit.
Species Types
Scientific Name
Parthenocissus quinquefolia
Description
Occasionally confused with poison ivy, Virginia creeper is easily identified by simply noticing that most of its leaflets are in fives, instead of threes. This common native vine is useful in landscaping.
Media
Illustration of woodbine leaves, flowers, fruit
Species Types
Scientific Name
Parthenocissus vitacea (syn. P. inserta)
Description
Woodbine is a climbing woody vine that usually sprawls over bushes and rocks. Its leaves have five coarsely toothed leaflets. Unlike the closely related Virginia creeper, its tendrils generally lack sucker disks. It is rarely found in Missouri.
Media
Photo of eastern prickly pear plant with flowers
Species Types
Scientific Name
Opuntia humifusa (formerly O. compressa)
Description
Cacti make us think of the desert southwest, but there is at least one species native to Missouri. This prickly pear grows in glades, sand prairies, rocky open hillsides, and other dry, sun-soaked areas.
Media
Photo of tickseed coreopsis flowerhead
Species Types
Scientific Name
Coreopsis lanceolata
Description
Native to Ozark glades and prairies, tickseed coreopsis has long been appreciated as a hardy garden perennial. Because of its popularity, it has escaped from cultivation and now occurs statewide.
Media
Photo of columbine flower closeup
Species Types
Scientific Name
Aquilegia canadensis
Description
Native to much of eastern North America, eastern red columbine's range almost matches the breeding territory of the ruby-throated hummingbird, its number-one pollinator. Its bloom time matches the hummingbird's northward migration, too.
Media
Narceus Millipede crawling across gravel
Species Types
Scientific Name
More than 900 species in North America north of Mexico
Description
Millipedes, which have two pairs of legs per body segment, are harmless detritus-eaters, move slowly, and curl up defensively when harassed.
Media
image of Paper Wasp on flowers
Species Types
Scientific Name
Polistes spp.
Description
Paper wasps are the most familiar of Missouri's social wasps. A late summer nest bristling with dozens of wasps can be an impressive sight. If you have a garden, however, these wasps are your friends.
Media
Photo of grass spider poised in funnel of her web
Species Types
Scientific Name
Agelenopsis spp.
Description
The funnel-shaped web of grass spiders is more often noticed than the spider itself. It is sheetlike, usually positioned horizontally, with a funnel leading downward to a shelter (a rock crevice or dense vegetation) where the spider hides, waiting for prey.
Media
Photo of a southern red-backed salamander on an oak leaf.
Species Types
Scientific Name
Plethodon serratus
Description
The southern red-backed salamander is small, dark, and slender, with a distinct, narrow, red or orange mid-dorsal stripe with saw-toothed edges. It hides under rocks, mosses, and rotten logs in Ozark forests.
Media
Photo of a western slimy salamander
Species Types
Scientific Name
Plethodon albagula
Description
You might not want to touch this salamander—it secretes a thick, very sticky substance that adheres to skin like glue. It causes dust, dirt or bits of dead leaves to stick to one’s hands and is difficult to remove.
Media
prairie lizard
Species Types
Scientific Name
Sceloporus consobrinus
Description
The small, gray to brown, rough-scaled prairie lizard is common in open forests. It often lives around country homes and rock gardens and on stacks of firewood and split rail fences.
Media
Image of a five-lined skink
Species Types
Scientific Name
Plestiodon fasciatus
Description
The common five-lined skink is Missouri's most common skink. Adults are olive or tan with lengthwise stripes. It is often called the blue-tailed skink for the coloration of juveniles.
Media
Image of a timber rattlesnake
Species Types
Scientific Name
Crotalus horridus
Description
Missouri’s largest venomous snake, the timber rattlesnake, is dangerously venomous, but there are few cases of rattlesnake bites in our state. It frequents rough country, is mostly nocturnal in summer, and few Missourians ever encounter it.
Media
Photo of a turkey vulture in flight
Species Types
Scientific Name
Cathartes aura
Description
The turkey vulture is perhaps the most commonly seen soaring bird in our state. Identify this "buzzard" from below by its shallow V-angled wing posture and two-toned pattern, with the forward edge of the wings black and the trailing half gray or silvery.
Media
Closeup photo of head of peregrine falcon
Species Types
Scientific Name
Falco peregrinus
Description
The fastest living animal, the peregrine falcon can dive at speeds of up to 261 miles per hour! It is being reintroduced to the state in urban areas, where skyscrapers replace the cliffs it traditionally nested on.
Media
Image of an american kestrel
Species Types
Scientific Name
Falco sparverius
Description
The smallest and most colorful of North American falcons, American kestrels are often seen along highways where they perch on telephone wires or hover over grassy medians as they hunt.
Media
Photo of three cliff swallow nests attached to the soffit of a building, with a parent attending.
Species Types
Scientific Name
Petrechelidon pyrrhonota
Description
Cliff swallows fly in swarms around their clusters of juglike mud nests attached to overpasses, bridges, and other structures. Note the whitish forehead, buffy rump patch, and chestnut throat.
Media
Photo of a barn swallow in flight.
Species Types
Scientific Name
Hirundo rustica
Description
Streamlined, agile fliers with forked tails, barn swallows build cup-shaped nests out of mud affixed to protected areas on the walls of barns and under bridges.
Media
Photo of an eastern phoebe perched on a small branch.
Species Types
Scientific Name
Sayornis phoebe
Description
Eastern phoebes often build their mud-and-plant nests on the side of a house, just under a roof or other overhang. These small flycatchers repeatedly cry out their own name: “FEE-bee! FEE-bee!”
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