Searching for Caves in the Northern Rocky Mountains

By Newell Campbell

INTRODUCTION

Many large, remote areas to search—few cavers. Cavers in the mountain west seeking to find and explore new caves face several impediments. Summers are short, access difficult, and perhaps motivation low; it is much easier to go to the same old cave rather than “waste time” looking for new ones. But for those wanting to find a big new cave and perhaps a bit of outdoor adventure, rest assured, the caves are out there, just need finding. This discussion is divided into three parts; a typical cave trip, useful aids to help locate new caves, and specific locations in Montana and Wyoming where the potential for new discoveries is great.

PART I
This is the story of two Montana speleologists, Joe Caver and Fred Finicky

Both are experienced cavers and both interested in finding a big new cave system in their state. A rumor surfaces at the last grotto meeting about a possible deep pit at the head of Leghorn Canyon in the Lost Range. Both cavers hope to be the first to find and explore this cave.

JOE heads home, opens Google Earth on his computer, finds Leghorn Canyon and begins a search for the pit. The Leghorn area is typical of high Montana mountain landscapes; trees are widely spaced and each casts a shadow that looks suspiciously like a pit. Other shadows cast by rock pinnacles appear to show crevasses that could be caves. Google is not helping as much as he anticipated. Still, Joe finds several depressions that look like sinkholes and one that looks like a possible deep pit. Joe copies the photo and marks the potential sinkhole sites.

Joe rounds up a couple of caver friends, runs down to the local Forest Service office, and buys a map of the suspect area. He asks at the FS desk if anyone has heard of the Leghorn Canyon Cave. Employees there don’t know Joe and are concerned that he might be artifact hunting or could damage the cave. Their policy is usually not to give out information on caves or suspected caves, so they give Joe no help. Undeterred, the cavers head for Leghorn Canyon.

Accessing Leghorn Canyon involves passing through private land owned by rancher Al Brunson. The crew stops at the ranch house, gets permission to cross the ranch and asks Al if he has heard of a cave up Leghorn. “Yup” says Al. “About 12 years ago one of my hired hands found a deep hole up there and threw rocks down the pit and never heard them hit bottom!” Al goes on, “Just climb onto the east rim, go past a bunch of trees to a small clearing with a square rock in the center. The hole is west of the rock. You can’t miss it!” All of this sounds good to Joe, so he and his crew follow the 4WD trail to the mouth of the canyon. The Forest Service map doesn’t show how steep and high the canyon rim is• looks to be at least a 3,000 foot climb that could take 6 hours or more to reach the upper canyon rim. Still, it’s only late morning, skies are clear, so the cavers head out.

FRED ‘Finicky heads home, checks Google Maps, and also finds them to be only mildly helpful. He heads to the town library and pulls the USGS 7.5 minute quadrangle maps of the Leghorn Canyon area. He sees there is 3,000 feet of relief between the canyon mouth and the upper cliffs-and the upper part is steep and cliffy. Fred needs more information before he attempts to climb those canyon walls.

Fred goes to the local Forest Service office. The receptionist and cave resource manager know Fred well as he visits the place often and has provided information about rock shelters and rock art within their area. Personnel at the FS office have not heard of a pit above Leghorn Canyon but ask Fred to provide them with any pertinent cave discoveries.

Fred also knows that in the past the Forest Service obtained low level photo coverage of their area, done by taking overlapping photos designed to provide stereoscopic views of the terrain. Although Google and other satellite coverage are now used, older stereo photos are often kept on file. Fred asks to look at these photos, and using a portable stereoscope, begin searching upper Leghorn Canyon. The west rim looks barren of caves and may not be limestone but Fred locates three possible pits high on the east rim. Sinkholes and pits are much clearer in stereo than on Google photos. Fred marks the pits on his Google photo map and on the 7.5 quad maps.

The resource manager at the FS office gives Fred the name of a retired ranger, Bart Green, who, as a “timber cruiser”, worked around the Leghorn Canyon area. Fred phones Bart, who remembers seeing a fairly deep pit along the upper east rim but can’t recall exactly where he saw it.

Fred heads home and immediately orders four aerial photo stereo pairs showing the east rim from the photo lab in Sioux Falls, South Dakota. They cost a few bucks but they show great detail and he can carry them along on his trip up the canyon. He is suspicious of the rock( and lack of cave features) on the west rim of Leghorn Canyon so he calls the Montana Bureau of Mines in Butte to see if any geologic mapping exists in the area. It does, and the librarian copies part of the geologic map and mails it to Fred. On the map’s arrival it is immediately clear that west rim is sandstone-no caves there-while the east rim is underlain by limestone.

Before heading to Leghorn Fred logs the GPS coordinates of suspected caves in his log book and on the map and photo margins. He rechecks the stereo pairs for possible routes up and onto the Leghorn Canyon east rim. Although steep cliffs guard most of the east rim, a faint game trail diagonals up the canyon and crosses the cliffs about two thirds of the way up, and looks to be the best route.

Fred has one last task prior to leaving-an overflight. He contacts a friend, Red Piper, who has a high wing airplane and considerable mountain flying experience. It costs $160 per hour to fly but Red’s hangar is not far away and his plane holds three passengers. Fred carries his photo map in front and two friends ride in back-one with a camera and telephoto lens, the other with binoculars.

On the first pass over the east canyon rim, Fred spots the pit; the pilot calls out the plane’s GPS coordinates as he passes over. One of Fred’s friends sees two other sinks with possible openings. The pilot makes a second pass and the binoculars show the main pit to have vertical walls and to be at least 40 feet deep. Red flies back down Leghorn Canyon along the cliffs of the east wall and the cavers spot at least three possible horizontal openings up-canyon from the game trail. Well worth the cost of flying.

Fred considers using a drone to fly over the east rim but his drone flying pal is concerned about taking his machine into such an isolated area. Fred makes a mental note to buy and learn to fly his own drone.

Fred assembles a crew and heads for Leghorn Canyon, about two weeks after Joe Caver’s group arrived. Rancher Al Brunson provides the same directions to Fred as he did to Joe; Fred’s air photos show several open clearings along the east rim, and one seems to fit Al’s description. Fred and crew arrive at the trailhead and are amazed at the size and steepness of Leghorn Canyon. They decide to stay overnight at the trailhead and get a very early start the next day.

JOE Caver and his crew (two weeks earlier), like most Montana cavers, are in excellent shape. They carry water, snacks, rain gear, and cave lights; they head up the bottom of the canyon. “We should be back by dark if we hustle” Joe says.

The canyon bottom is brushy and rocky, so about one third of the way up they cut up slope toward what appears to be a break in the cliffs along the east rim. The cliffs here prove to be barely climbable and they spend several hours finding a route to the top. Once on the rim they spread out and move upslope toward where the pit should be. After some searching they finally find the pit, which consists of about 40 feet of vertical walls with a talus slope at the base. Not too promising but it should be dropped-if they had rope and vertical gear. Instead, they continue up hill and soon find three other sinks, all plugged with debris.

By the time they get to the head of the canyon it is getting late! Joe and crew head down fast, and luckily find a game trail that diagonals down the cliffs and avoids all the rock climbing they had coming up. “Sure wish we had known about this before” laments Joe. Even so, they are forced to use their cave lights for the final 4 hours of hiking.

On the way back home one of Joe’s buddies says “That was a great trip! We found the pit, saw a bunch of elk and an eagle, so now all we have to do is go back and drop that pit”. Joe: “I’m not wasting time up there again. Next time I spend 18 hours caving it will be in a big cave like Bighorn Caverns”.

FRED and his group (2 weeks later) head up-canyon at 6am, carrying water, food, rain gear, cave lights, minimum mapping gear, 80 feet of rope, and one set of vertical equipment for the pit. Using Fred’s photos they quickly find the game trail through the east rim cliffs and spread out to find the pit. With photos and GPS they easily find the open pit-not very impressive but needs a look. Upon descending, the hole turns out to be only 45 feet deep plus 10 feet of debris at the base with no continuation. Bummer. The other three sinks are all plugged; the photos and flyover have already shown no other pits higher up.

But they still have the horizontal holes along the east canyon wall. The trio follows the game trail down to the base of the cliffs and then turns up canyon where the flyover showed cave openings. Along the cliff base they stumble on an overhang with some nice rock art. Fred takes photos and GPS readings to provide the cultural people back at the FS. After passing two small caves they come onto a good looking cave opening. A quick look shows that the cave goes! They rapidly explore about 400 feet of passage with two side leads-a great find! But there is not enough time to map so the crew heads back to their truck, using their cave lights for the last hours.

On the way back one of Fred’s crew says “Wow, that was a great trip! We saw a big mule deer and a bobcat, found some cool rock art, and discovered a new, maybe big, cave. We need to return right away and map it.”

SO? What kind of caver are you? Joe or Fred??

PART II
Searching for new caves and pits-techniques and suggestions

We have all been Joe Caver at times, Fred not so often-especially if we live in sparsely populated states in the west and don’t use all the resources available. This section provides suggestions for those who enjoy searching for undiscovered caves and pits, especially in isolated areas. Save yourself some time and energy and consider using some of the following.

Planimetric maps. Standard USFS maps are good for locating trails or unimproved roads (if they are not too out of date) but they are small scale maps and usually don’t show elevations. If you can get them from the FS, “fire maps” are far better-one inch to the mile and having yearly road updates and sometimes contours. Not all FS districts have these and those that do won’t often make copies for you. Far better to obtain USGS 7.5 minute (1:24,000) scale quadrangle maps, which, while costing more, show contours, peak names, streams, road names and other information. Some older issues even show larger cave locations. They usually have section, township, and range lines, and always latitude and longitude coordinates. If you can’t afford them, go to your local library and Xerox the sheets.

Geologic maps. These come in many scales, from 1:250,000 to 1:24,000 or larger (ie 1:24,000 means one inch on the map equals 24,000 inches on the ground). Many have contours superimposed on the geology. It’s always nice to know exactly where that limestone outcrop is located.

Photo maps. Satellite photography-Google Earth and other high altitude photo systems-have revolutionized remote sensing, but they may not best for cave hunting. Google-type photo maps are great for laying out timber harvest tracts, calculating the acres in a wheat field, or finding that restaurant in downtown Denver, but not so hot when trying to find a cave. I’ve spent countless hours looking at high altitude photos of karst areas, trying to locate a rumored pit in scattered timber with no luck-even using angle looking photos. And trying to locate a horizontal cave entrance-forget it.

Back as early as World War II, aerial photography, taken with automatic cameras that took 60% overlapping shots as the airplane traveled cross-country, allowed viewers to see the ground in stereoscopic vision-just like 3-D movies. Using a hand held stereoscope, or a large office stereoscope, researchers could see much clearer views of the ground. Soil Conservation Service, USFS, Armed Forces, BLM, engineering firms, and the USGS all used stereo pairs of photos in their work (and don’t forget, topographic maps are made from stereo photos). Then came satellite photography and stereo photos sort of disappeared.

However, some government offices still use them although they are often stuck away in a filing cabinet in the back room. Some of us can look at a stereo pair and see in 3D but magnification helps. Buy yourself a $15 stereoscope and learn how to use it. These photos will open up a new world of cave searching. Stereo photos come in black and white, color, and false color infared, although black and white are far more common. Often in USFS and BLM offices you will see several sets of the same area, taken in different years. It is helpful to look at all the sets as well as color and black and white• vegetation changes over the years. You’ll find that even horizontal cave entrances can be located using stereo photos, and tree shadows distinguished from open pits.

Can’t find photos of your area? Contact the national center at Sioux Falls, SD, and buy photos of your area. Also, state geologic surveys and the USGS will sometimes provide photos for a fee.

GPS. If satellite photography has redefined overhead viewing, GPS really changed the field of locating and surveying things. For example, on a suspected earthquake prone fault, we ran a 24 hour GPS triangulation survey, getting a reading every 15 seconds on both sides of the fault. A computer then averaged the 1000s of readings to give an accuracy of 1.4 centimeters per point! The survey was then repeated 10 years later to see if the fault was slowly creeping along (no earthquake), or was stuck and might suddenly shift, causing a quake.

Cave hunters don’t need centimeter accuracy but would do well to carry two or more units in the field in case one is damaged or lost; modern units are very light. Some areas have poor GPS reception (for example steep, deep canyons) and I’m always suspicious of readings taken in electrical storms but otherwise it’s a great tool. Airplanes and drones also carry GPS units-great for use in hovering drones, but readings taken from a plane flying 150 mph may be a bit off. Try taking a photo of the spot at the same time the GPS reading is recorded.

Plot and label GPS readings of suspected caves on your maps and photos before heading into the wilds. Then you can match readings in the field with those on the map (you do carry photos and maps along on your trip, don’t you?).

Drones. Drones are useful for more than scaring your neighbor’s barking dog. They are rapidly becoming an important tool for cave hunting, especially in steep, poorly accessible areas. Before you run out and buy that high priced toy, some advice. First buy a cheap model and learn to fly it correctly. Nothing worse than crashing your expensive machine into an inaccessible cliff. Second be sure your drone has a camera and GPS unit. You’ll need to obtain photos that you can study before heading into the hills. This means you need a way to print stills from the drone camera. Thirdly, watch where and when you fly. Wilderness areas are off limits-the FS treats a drone like a helicopter there-a no landing or take off zone. The fish and wildlife people in most states frown on disrupting wildlife, like deer and elk, during the breeding and birthing seasons. Check with your local game warden. And avoid flying your drone along well traveled horse packing or hiking trails. likewise it’s not a good idea to fly your drone over a busy campground at the crack of dawn. It might get shot down! And as I write this, the FAA and other state and federal agencies may have written a whole bunch of new regulations pertaining to drones. Check carefully. Still, drones have a place in cave hunting, and have been used successfully already in the mountain west and elsewhere.

Airplanes. In my view nothing beats a high winged aircraft (except maybe a high priced helicopter) for checking out cave and karst areas. A few passes over an area can make a huge difference in your search as well as locating access routes and other potential problems. And the pilot can fly along cliff faces so you can look for, and photograph, potential horizontal cave openings. Using a high wing plane like a Cessina or a Super Cub allows unobstructed viewing out both sides of the plane and you can cover large areas in a hurry.

Costs can be a problem. Experienced mountain pilots charge from $130 to as much as $230 per hour (stay away from tourist oriented pilots like those in Jackson, Wyoming, who will charge even higher rates). Still, if three of you fly and share costs, it helps and remember, a plane moving at 100 plus mph can get to that cave site and back very fast. Give flying some thought.

Be sure your pilot is familiar with the area and has mountain flying experience. How can you tell? Some examples of lack of experience. First, the pilot is looking at the same cliffs you are looking at, instead of where the airplane is headed. Second, your pilot is flying down the center of a canyon instead of along one edge, so he can turn around if he can’t get out the end. Third, flying the day after a storm, the pilot knows not to fly on the lee side of a peak or ridge because of post storm turbulence or downdrafts there. Also, make sure the airplane is capable offlying high enough to exceed the height of the highest peak in the area (one that didn’t lies at the head of Green Fork Canyon in the Scapegoat Wilderness in Montana}.

Considering the time saved hunting for that big cave, the effort expended hiking, climbing, searching, carrying massive loads of cave and camping gear, flying is a really good way to start a cave hunting trip.

Optics. Cameras aside, for lightweight magnification while backpacking, I carry an 8×24 small set of binoculars, about the size of a deck of cards. Other cavers I know use a monocular. Big telephoto lenses and large cameras are just too heavy for recon trips but some of the new light weight cell phones and miniature cameras should work well. However if you are looking over an area from the trail head or
high vantage point, consider a tripod mounted spotting scope, say 20x, or a variable power scope. These work especially well for glassing distant limestone cliffs. Wide angle, high power binoculars are also good, as are super large telephoto lenses, when using a rest. The advantage of a telephoto lens is that you can snap pictures of potential cave openings and then carry the pictures on your hike in.

People use. Perhaps the simplest and best way to locate new caves is by asking. Start with the locals• ranchers, farmers, hired hands, herders, etc. Some of these people can be as ornery as a two headed snake but most are very helpful and can also steer you to someone else with knowledge of caves. Just be really careful of placing too much stock in their directions. Old timers have their own way of route finding, based on living in one place all their lives and often can’t read maps too well. When they say “you can’t miss it”, you can, so ask for more details.

Next are the government agencies. The USFS and BLM are getting harder to get cave information from-and for good reason. Cave vandalism, even in remote areas is increasing, and destruction and removal of archaeological materials more common. Still, it’s good to get to know the local personnel, especially those people who have jobs taking them into the field. And retired employees are often more helpful because in the old days, rangers covered their area by horse and on foot; thus they were more likely to see caves and pits.

Include Park Service employees if you are cave hunting in places like Glacier or Yellowstone and some state parks. A trip to park headquarters is usually required to get any good information on caves.

USGS field geologists sometimes have information on caves, especially those who worked in or around wilderness areas. We are still trying to run down all the cave leads obtained from geologists who worked in and around the Scapegoat Wilderness. Don’t expect to find caves mentioned in their publications, however. I’m not sure why-maybe thrust faults and bioherms are more exciting than caves.

Hunters and horse packers. These are a good source of new cave locations. They love the back country areas that are off trail and rugged because that’s where the trophy animals live. Horse packers were the first to provide information on caves in the Bob Marshall Wilderness-back in the 1940s-before there were cavers around to explore them.

Pilots. They can sometimes be a source of information, especially the small plane pilots who like to fly tourists, hunters, or sightseers over roadless terrain. Several caves in western Wyoming were found first by pilots.

Miners. Older miners may have found caves for three reasons. First these old retired guys (if you can find them) tromped all over the mountains looking for ore deposits and checked out pits and caves in the process. Two, many ore bodies are in or near limestone outcrops, and three, due to acid generated by sulfide ores, there tends to be more caves near old mines than elsewhere. US Bureau of Mines and state mining bureau publications sometimes describe caves. Be sure and check for these if you are looking in a particular area.

Native Americans. Here is a source of information on caves often overlooked by cavers for several reasons. First, trespassing is highly frowned on by Indians. Second, many caves are part of a sacred area or legend, off limits to moat of us. Third, getting permission to visit a cave on tribal lands can be a long drawn out affair and very frustrating. However if you are patient and courteous, and if you offer to
bring along some tribal members to the cave, it can happen. And remember, some Native Americans are cavers too, and may know of all sorts of caves you have no idea existed.

Newspapers. Early cave explorers in this area, like Basil Hritsco, Howard MacDonald, and Royce Tillett, knew that newspapers often carried articles on caves and they searched “newspaper morgues” for information. You can do the same. Concentrate on small town papers, some perhaps now out of business, where folksy articles were popular. It’s a good place to start. One caver I know has amassed several hundred cave stories written over the past 100 years.

High tech remote sensing. For cave hunters who have just won the lottery, I include some exotic methods of cave hunting via the air. Although these are at present too expensive for the average caver, keep in mind that what is cost prohibitive now may be feasible in the near future, or you may find an ongoing study that you can obtain data from at low or no cost. Some possibilities are listed below.

Thermal Imagery. The theory here is that warm air can rise from a high volume cave out of an entrance or pit and be detected. If you fly during winter months the rising warm air will leave a thermal signature. We tried this, flying over the Scapegoat Plateau in winter, searching for a pit connecting to the river cave below. It was a crude attempt and unsuccessful in this case but has worked elsewhere and shows merit.

LiDAR. Laser pulses, sent from airplane or drone to ground and back, produce very accurate maps-less than one foot of vertical error. These have been used in a few places to search for sinkholes and caves (as well as ore deposits and faults). It is expensive to construct LiDAR maps but the big advantage is that vegetation can be obscured so you are seeing the true ground surface. Great for forested areas. If you ever obtain a LiDAR map look for Joint (fracture) sets, keeping in mind that if there is a pit or sinkhole on one fracture there may be more along the same joint. Also, look for places where joints intersect•
there are often pits there because surface water is coming from two directions (these suggestions also apply to ordinary air photos). Sinking streams and springs are more easily spotted than on normal photo maps, as are sinkholes and pits, but so will small glacial depressions (kettles) and depressions on hummocky landslide blocks-be careful of calling every low place a sinkhole. Because the laser pulses from plane to ground are vertical, locating caves along vertical cliffs is very difficult.

LiDAR is pricy but there is good news. Most states have LiDAR consortiums that coordinate and make available LiDAR maps, with the ultimate goal of complete state coverage. Contact your state agencies for more information. Also, the USGS, USFS, and BLM may have LiDAR maps available in certain areas. The USGS also offers a short course on LiDAR and karst-call 703-648-6027 for details.

SLAR–side looking airborne radar. This is another high priced system that produces excellent, accurate photo maps. These should work well for spotting both cave openings and surface pits. Since SLAR maps at a 30 degree angle to vertical, it should be able to “see” cave openings along vertical cliffs. Some regional SLAR maps are currently available-but cave hunters need low level detailed maps. I’m not sure if any caves have ever been found using SLAR but it shows great promise for the future.

Airborne gravity and magnetic surveys. These are expensive and don’t show enough detail to be useful for locating caves. One exception, aeromagnetic VLF-EM (very low frequency-electromagnetic) surveys are accurate but need a ground tower and are expensive.

Aerogamma surveys. This low(er) cost natural gamma survey is very accurate but has limited use in cave hunting except where gamma producing minerals exist in caves-like the uranium deposits found in caves in the Pryor and Big Horn Mountains of southern Montana and northern Wyoming. Both open and buried caves will show up as a narrow spike of increased gamma radiation on an aerogamma map.

There are probably other remote sensing methods that I missed but this is a start. Keep buying those lottery tickets!

PART lll
Areas in Montana and northern Wyoming with great cave potential

Introduction. Where should you go to search for new caves? I confine my suggestions to areas in Montana and northern Wyoming mainly because I’ve more hard data available there-other states should not be ignored. If you are just starting to cave hunt, first learn which carbonate rocks contain known caves; Mississippian rocks have the most caves but consider Devonian, Ordovician, and Cambrian carbonates, and don’t leave out Precambrian limestones and travertine deposits. All have known caves. What about cave rumors? When I was compiling cave data for the Caves of Montana study, and later for a caves of Wyoming effort, I listed every known and rumored cave and pit. Since then, most of those rumored caves have been located. The rumors were true! Some of the caves found were small, and the pits shallow but they existed. So don’t ignore cave rumors, no matter how vague. Below is a list of areas, in no special order, that I believe warrant a serious search (and some that don’t) for new caves, and I include some rumors and specific localities as well.

Finally, these are only my views on which are the best cave areas that remain to be searched, keeping in mind that there are many other good, unsearched places, and also that some of those listed here may have been checked recently. I believe that cave hunting in the northern Rocky Mountains is just getting started and in the future we will see a bunch of big, new discoveries.