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Overview

The old Calcium Products Company's mine is located at the crest of a small limestone hill overlooking the lake in what is now Canoe Creek State Park in Blair County, Pennsylvania. Today the mine is of little interest to mining companies but rather intriguing to hikers and hunters which occasionally pass by the gaping entrances. Cave explorers find the maze of tunnels curious for the number of intersecting natural cave features which may be only partially explored. Of much greater significance to biologists and the Commonwealth is the mine's rather accidental part in what is now the model bat ecosystem in the Northeast.

Brief history of the operation

In 1916 Mr. J.D. Hartman did not set out to create a perfect hibernacula for Pennsylvania bats. In fact, it is likely the thought never crossed his mind. Nine years later in 1925 he was probably elated to find that his operation was given high marks by the U.S. Bureau of Mines. Despite the seemingly bright prospects, in 1929 the operation ceased, apparently at the beginning of the Great Depression.

A letter written on February 4, 1925 by Oliver Bowles, then Superintendent of the Nonmetallic Minerals Station of the U.S. Department of Mines in New Brunswick, New Jersey, gives us a glimpse of the "roaring" 1920's setting:

"Dear Mr. Hartman:

I visited your limestone mine near Hollidaysburg, Pa. on November 8, 1923. At that time three drift faces had been projected, the deepest being about 320 feet from the entry. These drifts were 30 feet high and 33 feet high, and were being arranged in such a way that supporting pillars 30 feet by 30 feet would be left. The roof was very smooth and secure on account of an open roof seam in the rock. With a bed of good stone 30 feet thick, no drainage problem, a safe roof, and easy transportation practically on a level, this deposit is very favorably situated for underground work. I have visited quite a number of limestone mines and none that I have seen have more favorable conditions for mining. In view of the fact that one limestone mine I have visited has been in profitable operation for years hoisting stone through a vertical shaft nearly 400 feet deep, and another with an inclined shaft nearly 400 feet deep, a hillside drift such as you have should be even more profitable. It may interest you to know that I have a record of between 50 and 60 limestone mines now in operation in the United States, one of them having more than 4.5 miles of underground workings. Some of these companies are finding that costs are lower for underground than open pit work. The chief advantages of mining are (1) no stripping cost, (2) no contamination from overburden, (3) greater comfort for workers and no interruption from bad weather. Some disadvantages are: (1) usually a greater proportion of fines, (2) dynamite fumes, (3) about 30% of stone unavailable as pillars. There is so great an increase recently in underground production of limestone that I have secured the services of an engineer experienced in such work to make a complete study of the problem and to prepare a report on underground methods. This work is now about half completed."

According to newspapers of the day, the workers were largely comprised of Italian immigrants. Once the stone was hauled out of the mine, the manned cart then continued on tracks down over the steep hillside. The operator got quite a ride on this primitive roller coaster which must have intimidated many of the people required to operate it. If all went well, the "driver" was to use a crude hand braking system and stop the two-ton cart directly overtop of the lime kilns (Figure 1). After unloading, the empty cart was winched back up the hill and into the mine. It is unclear how many workers were accidently killed during the operation, but surely the rock coaster claimed more than one.

Realization of significance

The mine lay abandoned after 1930. The forest slowly consumed nearly all traces of Hartman's kilns, the death coaster, and other minor outbuildings. John Hall, Professor of Biology, fills in more recent history with his short May 7, 1984 paper entitled History of the Indiana Bat Population in Canoe Creek Mine.

"I first investigated the abandoned limestone mine at Canoe Creek, Blair County, Pennsylvania during the winter of 1964-65. A colony of approximately 1,000 Indiana bats, Myotis Sodalis, was found in a natural cave pit (the now infamous Pit 13) inside the mine."

"The mine was not visited again until October 1978, while I was conducting a survey of Indiana bat populations for the Pennsylvania Game Commission. It was discovered at that time that the entrances had recently been closed by bulldozing. After reporting the possible presence of the endangered Indiana bat in the mine, two entrances were reopened. However, permission to enter the mine was not obtained until November 1979."

"On November 10, 1979, the mine was searched for bats. The pit where the 1,000 Indiana bats had been seen in 1964, contained only 100 individuals. A group of 50 Indiana bats was found at the end of the side tunnel marked as site 21 (located at the western end of Indiana Avenue) on the map."

"In March 1982 the mine was again entered to count the bats. The pit contained no Indiana bats. At site 21 a group of 60 individuals was found. Apparently the popularity of the 60' deep pit for vertical caving by spelunkers has been too much of a disturbing factor for hibernating Indiana bats."

"The most recent survey of the mine on February 27, 1984 revealed 65 Indiana bats at site 21. This group appears to be stable and even increasing somewhat. This site apparently is not in an area popular with cavers. The Indiana bats in Canoe Creek Mine are the only known individuals of this endangered species in Pennsylvania."

"This mine contains the largest known winter colony in Pennsylvania of the little brown bat, Myotis lucifugus, 2,000-4,000 individuals."

"On February 27, 1984 I found 15 individuals of the rare small footed bat, Myotis leibii. This is the largest known group of this species in the state, and the most that have been seen since the survey by Charles Mohr in the 1930's."

"A few individuals of the big brown bat, Eptesicus fuscus; Keen's bat, Myotis keeni; and the eastern pipistrel, Pipistrellus subflavus are also found in the mine."

"The abandoned limestone mine at Canoe Creek State Park is the most important bat hibernaculm known in Pennsylvania. All six species of cave dwelling bats can be found hibernating in the mine. The only known colony of the endangered Indiana bat is found here. The largest numbers of little brown and small footed bats in the state are found in the mine."

"It is very important that the mine be kept closed to human traffic during the winter months. Proper gates and locks should be maintained on the entrances. The gates should be frequently checked for vandalism. Signs should be placed at the mine entrances explaining why the mine is closed, especially emphasizing the presence of an endangered species and explaining the endangered species act."

Not long after this report, the mine received custom fit gates on three of the entrances. The easternmost entrance has easiest access into the deep mine, and so it is the only gate built with a door.

In 1987 the Pennsylvania Game Commission began biannual surveys of the mine. Presently little brown winter populations have quadrupled since the 1987 survey while all other species have essentially remained the same. Approximately 15,178 visible bats were present in the mine throughout the winter in 1998. Despite an extensive search and better survey techniques today, the Canoe Creek Mine is still the largest enterable hibernacula in the state. The Durham Mine in Bucks County (10,794) is a close second, while the US Steel Mine (6,036, Armstrong County) and Fire Clay Mine (3,031, Fayette County) are a distant third and fourth.

Interior description

Today the mine is entered through the eastern portal. The gate is located on top of a bulldozed mound and gives access to the mine at ceiling level. By scrambling sixty feet down a somewhat treacherous rubble slope, the true floor of the tunnel is reached. The most striking feature of this mine is the grandeur of the passages which average twenty five feet wide and thirty feet high. After an easy walk of 330 feet west, the Main Drift is reached. This was the original main entrance to the mine operation in the 1920's. The workings might be visualized as being on six or more levels connected by short, steep slopes. The Main Drift is the "spine" of the mine, and is the only passage which directly connects every level. Apparently Hartman was conservative when laying out his tunnels, as nearly all of the remaining supports are more than thirty feet square. According to Bowles, by late 1924 the Main Drift was approximately extended as deep as we see it today. This would lead use to assume the rock was excavated in the horizontal tunnels extending away from the Main Drift from 1924 until closing. By working simultaneously on several faces, this would be the most logical way to quickly remove as much rock as possible.

Travelling down the Main Drift elevation is lost rather quickly until the last intersection with a eastern trending tunnel is reached, roughly 115 feet below the present day main entrance. This is the tunnel which contains the renowned Pit 13 mentioned in Hall's report.

In 1966 Frank Marks and Nevin Davis produced a sketch map of the mine showing twenty-eight cave features throughout the mine. As Hartman expanded his tunnel system, he encountered very small pockets of airspace formed when carbonic acid-laced water infiltrates and dissolves the limestone along joints and faults. Unfortunately, nearly all of the features are just "features"; parts of a dome, a ceiling channel, and crevices which do not lead more than a few feet. In fact, nearly all of these features are so physically small when compared to the mine tunnels they were purposely omitted from the modern full scale map to maintain legibility. It would appear from the layout of the remaining cave features, Hartman did not dissect a single large cave system, but encountered isolated pockets of cavelets which seem unrelated. Marks and Davis systematically numbered these features, but of the twenty-eight the only "name" which ever stuck was Pit 13. (See the Acrobat file for legible copy of chart below)

Pit 13 is not particularly difficult to negotiate. The entrance to the drop is from a window 25 feet off the floor of a mine tunnel, near the ceiling. An extension ladder is used to rig rope from bolts placed in the window which directly overlooks the 66' drop. The "window sill" is only about fourteen inches wide, with drops immediately on either side make the window sill a nerve wracking place to work from. Pit 13 gains it's notoriety from being the only place in over 22 years which required a full-fledged rescue of a PA Game Commission bat surveyor.

In the winter of 1987 Jim Kennedy was standing on a rubble pile twelve feet off the floor of Pit 13, looking at the map. The pile suddenly shifted, leaving Kennedy no choice but to leap into the hole and away from the ensuing avalanche. Some eleven years later he returned to Pit 13 and placed bolts to make the area more accessible and prevent some of the rigging problems which hampered his own extrication.

Other notable cave features exist along Indiana Avenue where one can gaze forty feet up into what appears to be major ceiling channels. Ceiling channels in this mine are actually cave passages where the ceiling of the mine has ripped away the floor of the cave, today leaving us the impression of a ceiling channel. These are for the most part unexplored due to their inaccessibility and are frequently encountered along the southern edge of the mine. After viewing the extensive cave dissection, it is not difficult to imagine a set of cave passages that may have connected Pit 13 to the western end of Indiana Avenue at one time on an upper level.

Pretty Well is another good stop when touring the complex. A mine tunnel intersects a small cave passage which leads into a seventy-foot high decorated dome. Fragments of other domes are scattered throughout the mine but Pretty Well has for the most part escaped the ravishes of blasting, and is much easier to visit than Pit 13. The only other significant cave development is located in the far northwest portion of the mine. Two crawlways lead into dome which was not surveyed. It's location in a rather large unexcavated portion of rock pillar suggests that there is "room" for more passages to be found there.

Location, location, location

Why are there so many bats in the mine? First and foremost, the mine is ideally set up physically as a hibernaculm. The spacious corridors are laid out on staggered levels, forming a distinct temperature gradient from the top of the mine to the bottom. Numerous domes and pits form microclimates which bats learn to exploit. The partially bulldozed entrances create a cold air dam which helps trap cool air inside the mine, making the bottom levels very cold and very stable. The entrances are also controlled so that human disturbances during critical hibernation periods are minimized.

Location is what makes a good site an outstanding one, being situated within one mile of all types of diverse central Pennsylvania summer bat feeding grounds. Meadows, agricultural fields, ridgetops, valley floors, forest, forest clearings, wetlands, streams, and even a lake. The food supply is constant until the final day before hibernation. Added to this, a very large (17,000 estimated count) maternity colony of little brown bats exists less than two miles from the mine entrance in an abandoned church also managed by the DCNR. During the mine survey in September 1999 an Indiana bat which was banded earlier in the summer within the maternity church colony was spotted in the mine at Feature 23. This represents the first positive evidence which links the large maternity roost with the large hibernation site. Later that Fall several other banded Indiana bats were caught in harp traps verifying the original sighting (photo below).

The Canoe Creek Church as well as the relatively new "Bat Condo" structure is managed strictly for bats. In With the maternity site so close to the hibernation site, all energy which is normally saved for Spring and Fall travel is not needed, dramatically increasing the chances of survival. Any particular little brown bat does not actually have to leave Canoe Creek Park as food diversity, summer roost, and hibernation site are all readily accessible.