THE PROYECTO ESPELEOLOGICO PURIFICACION

Text and photos by Peter Sprouse

With the PEP now reaching its 25th year, it is a great time to look back on its history and evolution. In 1978 David Honea expressed the Project's goals in a "statement of hope and intent" which we can feel proud to have accomplished. Those goals of excellence in speleology and respect for the area's environment and inhabitants have guided us through the years. On my first trip to the Purificación Karst Area in 1976, it could be described as basically another speleological reconnaissance zone, with a few moderately extensive caves but nothing yet major. A core group of cavers grasped its potential, virtually moved into the area, and with the adoption of a name became the first modern Mexican caving project. And ever since, there has been steady and spectacular progress in developing some of the world's outstanding cave systems. Sistema Purificación, now 95 km long and 957 meters deep, is the longest surveyed cave in México, and other caves of the area such as 36-kilometer-long Cueva del Tecolote continue to grow as well. Yet it seems likely that most of the potential of this vast underground complex has yet to be realized.

The Purificación Karst Area straddles the border between the southern parts of the Mexican states of Tamaulipas and Nuevo León. It comprises the front ranges of the Sierra Madre Oriental which rise from an elevation of 400 meters at Ciudad Victoria to an altitude of 3500 meters on Cerro el Viejo, the area's highest peak. Moderately fractured Lower Cretaceous limestones on the west flank of Huisachal-Peregrina anticline have provided an ideal environment for development of extensive cave systems. The boundaries of the PEP study area have been selected using major surface drainages which might be expected to limit the extent of any subterranean drainage systems. The coastal plain forms the area boundary on the east, and to the south of Cd. Victoria it proceeds west up the Arroyo Juan Capitán through the Huisachal valley to the Río Chihue. It follows this drainage to the northwest up the Río Alamar branch to San Pablo, then north past El Refugio to the Río Blanco. The area boundary then follows the Río Blanco east to its confluence with the Río Purificación at the coastal plain.

Cavers first entered the high mountains northwest of Ciudad Victoria, Tamaulipas in 1971, and in the ensuing five years Texans from Houston, Austin, and McAllen made independent forays from time to time, following the myriad logging roads through the pine forest and exploring various caves and pits. Longest of these was Cueva del Brinco ("Jump Cave"), which had been mapped for about 1000 meters by David McKenzie and companions. The beginnings of the PEP can be traced back to May 1976, when McKenzie led a trip back to Brinco. Situated at 1900 meters elevation in an east-facing mountain cove, the entrance to Brinco opens into a steadily descending bedding plane passage, with regular and complex side passages leading off. In a series of trips over a year's time various stream passages were pushed steadily downward, reaching the a major trunk passage called the World Beyond at a depth of 200 meters.

At the same time, a group of cavers from the Greater Houston Grotto had begun the exploration of Cueva de Infiernillo, located 5 kilometers north of Brinco and 820 meters lower in Cañon el Infiernillo. This canyon begins abruptly at the base of a cliff hundreds of meters tall, and 40 meters up this wall is the large entrance to Infiernillo, a tunnel 20 meters wide and 25 meters high. In April 1976 the Houston cavers led by Charles Fromén led a route up into this entrance, and found a large network of tunnels trending upward to the south, blowing air. We immediately saw the potential for connecting the two caves, and started the survey of Infiernillo's vast complex of passages. Due to an access time of about 4 hours to hike to the entrance and climb up to it, underground camps were used from the beginning to explore and map all passages in Infiernillo. An initial complex of ascending passages and boreholes soon led to a bewildering maze in scalloped bedrock, the Confusion Tubes. While a route was soon found through the Tubes to a continuing level borehole, the Tubes themselves steadily grew into an enormous complex which even today still contains hundreds of unexplored leads.

Throughout 1977 rapid progress was made in both Infiernillo and Brinco. By June 1978, we had mapped 9568 meters in Brinco to a depth of 389 meters, and 7148 meters in Infiernillo to an overall height of 442 meters. The remaining gap between the two caves was 1300 meters horizontal and 125 meters vertical. Camp II was established nearly 3000 meters inside of Infiernillo, and a fortuitous lead off of the Nile River area was explored upwards into the lower reaches of Brinco. When the survey was carried downward from the Brinco end a few weeks later, Sistema Purificación was at once the longest cave in México at 20,068 meters, the deepest cave in the Western Hemisphere at 884 meters, and contained the deepest through-trip in the world at 820 meters.