Distribution of Limestone Caves in the Western United States (Speleodigest #5)

William Halliday, DC Speleograph, December 1957

Perhaps nowhere in the world do caves occur under such a variety of conditions as in the western United States. In addition to the dramatic enviromental differences of the various geographical provinces, the speleoliferous limestones vary from horizontal to vertical, and range in age from Pre-Cambrlan to Pleistocene. In addition to solution caves in limestone, gypsum, and perhaps salt, probably every other type of cave ITBY be found. Lava tubes are numerous. Litteral caves are prominent not only along the Pacific Coast, but on the shores of Pleistocene lakes in the Great Basin. Sandstone and other rockshelter caves are often of major archeological interest. Travertine caves arising from several types pf deposition are not exceedingly rare. Talus caves are sometimes of surprising size and interest. Even major glacier caves are important locally.

In terms of limestone solution caverns, the western United States divides itself into a number of areas:

1. The Coast Ranges and Cascade Range

2. The Sierra Nevada

3. The Basin Ranges

4. The Rocky Mountain areas

5. The Mid-Arizona Zone

6. The Texas-New Merico areas

7. The Black Hills

The Coast Ranges contain relatively little limestone and hence few caverns despite their length. Their extreme ruggedness seriously hinders investigation in many known cave areas, such as the Shasta Lake-Trinity Mountain area. North of Santa Cruz, California, several small caves are present in marple of uncertain age. The Cascades and their eastern counterpart, the Okanagan Range, are little better. Several small caves are' known in narrow bands of limestone which extend as far south as ' Srogualmie Pass, Washington, where a new cave area has been discovered this past summer. Gardiner (Crawford) Cave, in the Okanogans, appears to be the largest limestone cave in Washington. The central Cascades are volcanic, but south of Grant's Pass, Oregon, caves again appear in the tangled Siskiyou area which intergrades into the Coast Ranges to the west. Oregon Caves, several small caves in'the Trinity River area, and several in the Shasta Lake area are worthy of mention.

The Sierra Nevada is the leading cave area of the Pacific States. North of Yosemite,Valley, the caves occur in the Carboniferous Calaveras formation. To the south, they are in heavily metamorphosed limestones which are believed to be in part Triassic and in part Paleozoic. In both cases, the limestones are found in roof pendants. While the characteristics of the caves vary greatly, they often reach unusual depth for western caves. Several of the southern group reach the 100-200 meter rapge. Many are isolated, but particularly in portions of Calaveras and Tuolumne Counties and in the Sequoia National Park area they are densely grouped. It should be noted that the entire Southern Sierra group was not included on the map in Frank Folsom's recent book, illustrating the distribution of caves in the Western United States.

The ranges of the eastern and southern parts of the Great Basin present perhaps the most varied of the western cave terrains. In these vast expanses of tilted limestones of Paleoloic age, local influences so strongly affect the caves that only a mile or two from the roomy, stalagmite-blocked passages of Lehman Cave, Nevada, the equally large Baker Creek cave system consists of bare, tortuous crawlways. While the majority are probably in Cambrian limestone, somll occur in limestone of each division of the Paleozoic, and even in the Pre-Cambrian limestones. Perhaps the longest is 2300 foot Cave Valley Cave; Nevada, although new discoveries in Model or Lehman Caves, Nevada, may surpass this figure. Probably the deepest is Cave of the Winding Stair, California (about 305 feet), Speleothems are often dramatic, and sometimes unique. Cave bubbles, folia, mammillaries, fascicular aragonite,calcite blades and rosettes are but a few of the rarer types found in this vast area, where caves are sparse but remarkable. An eastern hemicircle with a 50-mile radius, based on Ely, Nevada, includes the greatest concentration in this area, with a smaller circle around Cima, California, the next greatest.

The Rocky Mountains are a heterogenous and intermingled group of ranges. Speleologically, a rather bizarre division seems to serve best:

1. The Wasatch Range forms part of the western border of the Rockies. Its caves show more dissimilarities than similarities. Most are in Mississippian or Cambrian limestones, but Logan Cave, Utah, which with Minnetonka Cave, Idaho, is one of the two longest (about 2500 feet), is in Ordovician limestone. In most cases, the bedding is moderately or heavily tilted. Neff Canyon Cave, the deepest, will probably range from 500 to 600 feet when fully mapped. Either it or Church Cave, California, is the deepest cave known west of the Continental Divide in the United States.

2. The Markagunt-Paunsaugunt region of the southern Wasatch Plateaus contains a few small solution Caverns in the lacustrine Tertiary Wasatch formation. All known are essentially horizontal. The largest appears to be that of the resurgence known as Cascade Springs, the source of the Virgin River.

3. The Mississippian flanks of the Uinta Mountains of northeastern Utah are an excellent pooential caving area, hut are poorly known due to their. inaccessibility. The limestones generally dip moderately, but Sheep Creek Cave is a horazontal two-level cave in vertical limestone .with a stream on the lower level. Big Brush Creek Cave consists of several enormous rooms and a maze of small passages which are as yet barely entered.

4. Limestone caverns in the Montana-Wyoming area appear to occur very sparsely due to the spotty distribution of limestone. In Montana, they occur in a zone extending from Yellowstone to Glacier National Parks, including deep Lewis and Clark (Morrison) Cave. Several occur in the Snowy Mountains, and the Pryor Mountains and their Wyoming prolongation contain even more, although becoming progressively sparser to the southwest. They vary from Mississippian to Pre-Cambrian limestone, although only one of the latter has been reperted. The West slope of the Teton Range and part.s of other ranges along the western border of Wyoming are fair "cave country," as are Wind River Range and an ill-defined area just east of Yellowstone National Park including Shoshone Cavern.

5. In Colorado, limestones also occur very irregularly, and the caves tend to occur in isolated groupso It appears that the majority of the caves are in Mississippian limestones except on the "Eastern Slope" of the Rockies in Colorado and extreme southern Wyoming. North of Denver, these are in Pennsylvanian forrmations,as are those of the Sangre de Cristo Range. To the south, including Cave of the Winds, they are in Ordovician limestone. Probably the greatest concentrations of caves are at Glenwood Springs and in the Colorado Springs-Canon City area.

A curved zone in mid-Arizona, stretching from the northwest to the southeast corner and encompassing primarily "high country" is quite speleoliferous. Most of the caves are in Mississippian limestone (Redwall and Escabrosa) and many are of large size. Collossal and Crystal Caves in the southeast are perhaps the largest, but some in the Grand Canyon area can challenge them. In the Pennian Kaibab limestone of the Flagstaff area, solution cracks replae solution caves. At Montezumas Well, the caves are in lacustrine limestone of supposedly Pleistocene age.

A detailed survey of the caves of Texas is currently in progress, and a statement of the distribution of the caves of that state is premature. The Edwards Plateau of central Texas, however, is one of the great cave areas of the United States. The Big Bend-Devil's River area contains "numerous small caves”

The Carlsbad area. primarily in New Mexico, but extending into the western tip of Texas, is America's greatest caving area of limited size. The area immediately surrounding Carlsbad Caverns itself is riddled with caverns, many of great size. Carlsbad itself is the supreme American cave. with a known depth of 1050 feet, and with a single room 1800 feet long, 100 to 300 feet wide, and up to 285 feet high. Even though the cave is clearly far from completely explored, it is unlikely that its total length compares with that of the caves in the extensive, level eastern limestones like Mammoth and Crystal Caves. The speleological potentialities of this state have not been properly surveyed, but limestone caves are reported in the ranges on both sides of Santa Fe and east of Albuquerque, at Fort Stanton, near Artesia, and caves in gypsum in the eastern part of the state.

Many caves are known in the ring of Mississippian Pahasapa limestone which encircles the Black Hills of South Dakota. Probably the largest is Wind Cave, with about a mile of mapped passages, and "ten miles explored." Characteristic of many caves of this area is the occurrence of calcite scalenohedrons and rhombohedrons, and of remarkable development of the petromorph known as boxwork. In general, stalactites and stalagmites are poorly developed, although Rushmore Cave is a notable exception. A couple of small caves near Newcastle, in the Wyoming foothills, are probably in a younger formation.

It is hoped that present and futture studies will better delinate the nebulous outlines of these areas. Some of them have perhaps been overextended in an attempt to include almost every westrern limestone cave reported to date. The caves of the western United States are tremendous, but the difficulties of terrain and distances are almost equally great. The enthusiastic caver should not be daunted by these difficulties, for the rewards are more than proportional.