Lilburn cave, with 25.6 KM of passage, is one of California's two largest caves. With its very unusual flushing and gushing resurgence spring, it has attracted cavers and speleologists since the 1940s. Over its long history of use, some of the formation areas in Lilburn cave have suffered damage. Fortunately there is little formation breakage, but the very muddy nature of some passages has resulted in dirty formations.

In 1993, the Lilburn Cave Restoration project started to try to undo some of that damage and prevent further damage. Since then several trips each year have been dedicated to cleaning formations, flagging trails, and installing direction signs.

During the course of our cleaning, we have had the opportunity to experiment with many techniques. We have made extensive use of water from spray bottles and brushes for removing mud from formations. We have found the dry brushing is frequently sufficient to remove carbide soot from walls. In cases where mud has become embedded in calcite, we have used both sulfuric acid (H2S04) and hydrochloric acid (HCl). Our experience is that the hydrochloric acid is more effective.

We have also tried more unusual techniques, such as: Pieces of tape on the end of polls to pick mud off formations are not very effective. Eye droppers and turkey basters to suck dirt out of pools are reasonably effective. Sponges to soak up soiled water are necessary to protect unsoiled formations. We even once used a stream of water from a caver's mouth when no spray bottles were available which was quite effective.

The value of flagged trails through sensitive areas is well understood and many caving areas have adopted the practice. In Lilburn, some of the damage comes from parties who have become confused about the route. Installing signs (written on flagging tape) at junctions likely to cause confusion has reduced the impact of route confusion on passages people did not even intend to enter.

We have progressed from having to clean formations which were dirtied many years ago, to the point where exploration teams which dirty formations help organize restoration trips to clean those areas. A

quick cleanup is a lot more effective than one that must remove years of calcite deposition.

In 1997 we ran three restoration trips. There were two trips to the area under the Jefferson Memorial, and one trip to survey restoration sites and determine their current condition.

Digging occurred in Sequoia National Park in 1997 at one location.

Location 1. During the winter of 1996/1997 a tree in the bottom of a sinkhole ("Meatbug Sink") about 0.4 miles NNW of Lilburn Cave toppled, revealing at its base a too-small cave opening. In one morning of May 1997, approximately four Cave Research Foundation members moved about one dozen head-sized cobbles up from the hole into the bottom of the sink and then entered a body-sized chamber beneath the former tree. From that perspective it was clear that the "passage" terminated in a tightly packed boulder choke, and the site was abandoned to let the winter of 1997/1998 finish the job.

The years have not been kind to the historic entrance to Lilburn Cave. The current structure was built in the ‘70s (?) and updated in the ‘80s. At that time the constructors placed a ladder to eliminate any need to jump the 10 feet to the floor. While the main vault remains solid, the ladder has since lost a rung and the floor has washed away leaving the remains of the ladder propped up on a precarious set of rocks.

This summer we started preliminary repairs. Between dive sherpa trips I placed a form and hauled up rocks from below the second ladder to prepare for pouring. Jeff Cherez arranged for a shipment of cement and re-bar to come by pack mule with this summer’s shipment of dive gear. At a later expedition Saturday, John Tinsley and I added more rocks and poured the first course of concrete. The next day we continued the process with several more concrete sherpas helping out. At the same time Peter Bosted solidified the base of the second ladder.

Currently there is a first step poured as a base. It sits between bedrockish boulders delimiting the passage as one goes in the cave. The form has been moved and a second step has been started. The design is impromptu, depending on what was on hand at the time but it has followed several principles. The new floor structure should be aesthetic as well as durable. It should send water down the by pass and not down the main passage. It must be ready to support the new ladder when one is ready. It must allow easy passage of a stretcher in the event of an emergency. It should include anchors in case one is needed in an emergency.

The next operation will finish the second step and the pouring of the floor. This floor will probably be at the level of the concrete walls currently in place. When the it is poured we will leave two holes in contact with the underlying dirt (with maybe some gravel thrown in) which will allow some extra drainage but more importantly be in position to accept the legs of the ladder so they cannot swivel while someone is climbing it. There is still cement at the cabin but winter humidity may make it less than useful. We will reassess the situation and try to complete the project this Spring.

Little new rescue preparation happened this summer however we did see one incident which tested our preparedness for problems. A caver could not ascend the 42 foot cable ladder at Meyer entrance. Quickly a cohort of haulers came over from the cabin with a dynamic rope and the cache of webbing, carabiners, and pulleys. The belay line became a haul line with a prusik knot rigged to capture progress. We belayed with the dynamic rope from a separate anchor on the other side of the constriction. Several pulleys deviated the rope through the constriction above the top of the pit. The caver was hauled out without incident.

The second cache is now in the cave. This makes one at South Seas Junction and one at E5 in the Sandy Floored Walking Passage near the Hex Room. The caches are in green .50 caliber ammo cans. Each contains splinting material, an exposure blanket, hot packs, and iodine tablets for water disinfection.

Please report any use of either cache to the expedition leader and the medical officer. The medical officer will be routinely checking the caches to be certain that they are up to date and that the desiccant is still dry, so absent an emergency, there is no need for cave parties to open the ammo cans to check on them. The desiccants will last longer if the cans are not molested.

The phone line is now working (except for the ringer at the cabin). In the event of a real emergency the plan would be run extra phone line from the nearest drop to where the patient is. Additional phones could be set up along the evacuation route as materials are available.

William Howcroft and Jack Hess

The following report describes efforts made in 1997 to better understand the hydrology of the Redwood Canyon karst aquifer located within the General Grants Grove section of Kings Canyon National Park, Tulare County, California. In short, two main tasks were accomplished in 1997: 1) the installation of a hydrologic monitoring station upon Redwood Creek, and 2) the collection and analysis of water samples from springs, surface streams, and cave drips. Each of these tasks is described in detail in the following paragraphs.

On November 1, 1997, a hydrologic monitoring station similar to that currently existing at Big Spring was installed on Redwood Creek.. The monitoring station was constructed a short distance downstream of the point at which the Hart Tree Trail crosses Redwood Creek to join the main foot path through Redwood Canyon. Permission to install the monitoring station at this location had previously been obtained from the National Park Service earlier in the year. This particular site was chosen for a number of reasons including: 1) its location upstream of the contact with the marbles, 2) the relatively straight stream channel in which to conduct discharge measurements, and 3) ease of accessibility.

The purpose of installing a monitoring station at this location is to gain a better understanding of the amount and character of the main water input into the Redwood Canyon aquifer. Towards this purpose, a staff gauge and Campbell Scientific 21X datalogger with a pressure transducer, water temperature, specific conductivity, and air temperature probes were installed at this location. The datalogger is currently powered by 12-volt batteries with data recorded onto a storage module. In 1998, stream discharge measurements will be conducted within the stream channel at varying flow rates with which a rating curve may be constructed to convert the continuously recorded stage measurements to flow rates. A trip is scheduled for Martin Luther King holiday weekend to check upon the continued operation of the monitoring station.

For the purpose of identifying a natural tracer which might be utilized to conduct hydrograph separation of Big Spring discharge, two rounds of water sampling were conducted in the Redwood Canyon karst aquifer during 1997. The first sampling round was conducted over the weekend of September 26-28, 1997 whereas the second sampling round was conducted during the weekend of November 1-3, 1997.

During the first sampling round, water samples were collected from four surface water locations: Redwood Creek, Volvo Creek, Mays Creek, and Pebble Pile Creek. In addition, water samples were collected from two drip locations within Lilburn

Cave: within the East Stream area and at the Yellow Hungas Thing formation. Lastly, water samples were collected from the East Stream itself, at Big Spring, and at a small spring along the Hart Tree Trail. During the second sampling round, a water sample was also collected from a drip within the Hex Room. Collected water samples were analyzed for pH, electrical conductivity (EC), major cations and anions, bromide, strontium, nitrates, trifluoroacetate (TFA), and the stable isotopes of oxygen-18, strontium, deuterium, and carbon-13. Isotopic analyses, excluding strontium, were conducted at the Desert Research Institute (DRI) Isotope Laboratory in Las Vegas, Nevada. Strontium isotopic analyses is being conducted by the U.S. Geological Survey but is not yet complete. Major parameter analyses were conducted at the DRI Water Resources Center Water Laboratory in Reno, Nevada and TFA analysis was conducted at the Center for Environmental Sciences and Engineering laboratories, University of Nevada, Reno. With the exception of strontium isotopic data, complete laboratory data is available for the first set of water samples collected. For the second set of samples collected., only trifluoroacetate (TFA) results are thus far available.

Laboratory analytical results for the first round of water samples collected, excluding those for TFA and stable isotopes, are presented in Table 1. Bearing in mind that the water samples were collected for the purpose of identifying a natural tracer suitable for hydrogaph separation, the laboratory results were examined for analytes which are present in relatively unique concentrations relative to their input type, i.e., surface water vs. epikarstic (drip water) inputs. With this in mind, a number of analytes can be neglected: bromide, which was undetected in all samples; strontium and sulfate, which are non-conservative; and total organic carbon (TOC), whose concentration is below detection limit at Big Spring. In addition, calcium, magnesium, bicarbonate, nitrates, and potassium are all non-conservative and cannot be used as tracers. Likewise, pH and electrical conductivity are indicator parameters and are unsuitable as tracers. This leaves silica, chloride, and sodium as possible tracers. Silica, chloride, and sodium should be relatively conservative in a karst system. However, the observed chloride concentration in the East Stream is remarkably high in comparison to the other inputs. The reason for this high concentration is not known but suggests that the stream has a unique source. Sodium and silica concentrations are generally lower in drip waters than in surface waters. Therefore, the two analytes may prove to be useful tracers; however, additional sampling is required to required to ascertain the time invariance of the concentrations.

TABLE 1: ANALYTICAL RESULTS, SEPT., 1997 SAMPLING ROUND

All concentrations reported in mg/l. RC: Redwood Creek, VC: Volvo Creek, MC: Mays Creek, PPB: Pebble Pile Creek, BS: Big Spring, HTS: Hart Trail Spring, ES: East Stream, ESD: East Stream Drip, YH: Yellow Hungas Thing formation, HRD: Hex Room Drip.

Laboratory results for trifluoroacetate (TFA) for the two sampling rounds are presented in Table 2. TFA is a primary breakdown product of chlorofluorocarbons, is suspected to be detrimental to plant growth and aquatic environments, and has been detected in moderate concentrations in fog, rain water, surface water, and snow at locations within Sequoia National Park. TFA was considered to be potentially useful as a tracer in that it should be present in only younger waters. Examination of Table 2 reveals extreme variability in results, in terms of both water type and over the course of the one month time period between sampling events. This indicates that TFA is not a suitable tracer for hydrograph separation. Nevertheless, the high concentrations observed in drip samples collected from the East Stream area and in the Hex Room are of interest. TFA concentrations at these locations are among the highest recorded in the Kings Canyon/Sequoia Parks area. With the exception of the East Stream Drip, TFA concentrations decreased at all locations during the one month time interval between the two sampling rounds. At the East Stream Drip, TFA concentration increased by almost an order of magnitude. The reason for this variability is at present unknown, but may have to do with the complexity of epikarstic flow mechanisms.

Table 2: TFA Analytical results

All concentrations reported in nanograms per liter. RC: Redwood Creek, VC: Volvo Creek, MC: Mays Creek, PPB: Pebble Pile Creek, BS: Big Spring, HTS: Hart Trail Spring, ES: East Stream, ESD: East Stream Drip, YH: Yellow Hungas Thing formation, HRD: Hex Room Drip.

Results of isotopic analyses conducted on water samples collected in September, minus those for strontium, are presented in Table 3. With the possible exception of deuterium, the isotopic signatures appear to be rather variable among input type, making it unlikely that isotopes can be utilized as a tracer. Somewhat interesting among the results, however, is the strongly depleted carbon-13 signatures displayed in samples collected from Pebble Pile Creek and the Hart Trail Spring.

Table 3: Isotope analytical results

Isotopic signatures reported in per mil VSMOW (O-18, D), per mil PDB (C-13). RC: Redwood Creek, VC: Volvo Creek, MC: Mays Creek, PPB: Pebble Pile Creek, BS: Big Spring, HTS: Hart Trail Spring, ES: East Stream, ESD: East Stream Drip, YH: Yellow Hungas Thing formation.

Pebble Pile Creek is fed by a non-carbonate spring located at a high elevation below the summit of Big Baldy. Since the Hart Trail Spring is also a high elevation, non-carbonate spring, the two waters appear to be similar and vegetation associated with these high elevation areas may be responsible for the depleted signatures.

In 1998, a number of tasks are planned for the purposes of better understanding the hydrology of the Redwood Canyon aquifer. Continued sampling and analyses will be conducted with the hopes of identifying potential tracers suitable for hydrograph separation. In addition, stream discharge measurements will be conducted at each location for the purpose of constructing or improving existing rating curves. Further, dataloggers at Redwood Creek, Big Spring, and in the Z Room of Lilburn Cave will be maintained and/or repaired. Floods in early January of 1997 induced hydraulic heads greater than 100 feet within the Z room (see attached figure). Consequently, the datalogger at that location was inundated with water and is no longer operable.

Figure 1: Record of Stage, Z Room, Lilburn Cave. January 1997.

The following people have helped considerably with the work outlined in the previous paragraphs: Darcy Howcroft, Mike Spiess, Brad Lyles, Todd Mihevc, Ron Hershey, Eric Harlow, and Cathy Crowley. In addition, the Desert Research Institute and Cave Research Foundation provided financial support, equipment, and/or material assistance without which, this work could not have been conducted.

By John Tinsley

The winter of 1996-1997 was a banner year for sediment movement in Redwood Canyon and within Lilburn Cave. The wet, deep, early-season snowfall of November and December, plus an El Nino (Pineapple Express) weather pattern, extending from Hawaii to the southern Sierra Nevada, that dumped near-record quantities of warm rain during the first week of January, 1997, resulted in levels of runoff in Redwood Canyon that were sufficient to blow the sediment plug from the Upstream Rise and Big Spring sections of Lilburn Cave, and erode all fine sand that comprised the low set of fill terraces extending downstream of the Big Spring resurgence in the bed of Redwood Creek. There was no fine sand to be found in Redwood Creek channel; only pea-size gravel could be found among the coarse boulders in Redwood Creek. At Big Spring (the resurgence of Redwood Creek below Lilburn Cave) water boiled up through the tree roots upslope of the normal single spring orifice and a thin deposit of coarse sand was deposited on the previous season's forest soil.

Within the cave, the elevation at which cavers' footprints disappeared on the floor of the Hexadendron Room and in the lower part of the Corkscrew, as well as the points of inundation measured on static sediment samplers deployed in the Lake Room and White Rapids areas indicate that approximately 130 to 140 feet of head was attained above the Z-Room piezometer maintained by Jack Hess. Hess reported that the instrumentation was inundated, owing to the extreme pressures. Every southward-oriented passage from the level of the Bicycle Passage and below bore witness to the movement of large volumes of sediment.

The Pebble Pile sinkhole became filled with sediment to its downstream lip, and water flowed in the creek channel across the former sinkhole for the first time in nearly a decade. The progressively infilling the sinkhole has taken 9 winters to complete, with contributions of sediment having been derived from backwasting of the hillslope as well as from bedload transported by Pebble Pike Creek. The original sinkhole collapse represented a volume of about 140 cubic yards of sediment dumped into Lilburn Cave near the Yellow Floored Domes area. The impact within the cave was immediate, with the standing water level raised approximately 12 feet in the South Seas and an aggradation of the bed of the cave stream of approximately 10 feet was observed at the Z-Room area the same season the sinkhole was observed by Howard Hurtt.

Inspection of the 5 dozen sinkholes upstream of Lilburn Cave revealed that winter runoff had dropped the floor of Meat Bug Hole about 1.5 meters, and a body-sized passage could be observed extending downstream. Brad Hacker led an exploration effort there that terminated in a boulder choke after a couple of body lengths of passage had been stabilized. Farther north above the Great North Cave, a landslide is feeding a large sinkhole along an unnamed tributary approximately one mile up canyon from the field station.

In summary, the 1996-7 winter proved to be a wholly remarkable performance by a dynamic karst hydrologic system.

Cave Diving,1997 Accomplishments
By Bill Farr

• First mixed gas diving in Big Springs including custom dive tables for mixed gas decompression at altitude.
• Big Springs bottomed at -248 ft at 900 ft in. Currently we are at -243 ft depth at 1000 ft penetration, with the way on through a 10 inch high crack, 4 ft wide.
• Refinement of techniques for extended deep diving at high altitudes in cold water, including first test of a battery operated chest heater for decompression.
• Breakthrough in the Upstream Rise. Beyond a previous sand block 250 ft. in, entered a phreatic borehole that has continued to 1200 ft. penetration with no apparent side passages. Maximum depth (at the ceiling) is -163 ft. Currently back up to -141 ft in a 15 ft diameter tube.

1998 Objectives

The year 1997 saw good progress in the effort to completely explore and survey Lilburn Cave and the other small caves located in Redwood Canyon, Kings Canyon National Park, California. This project began in 1980 under the auspices of the Cave Research Foundation, and through 1996 had surveyed about 25.4 km in Lilburn, and under 1 km in Cedar and May's caves.

Surveying of dry parts of Lilburn took place on eight different expeditions in 1997 (April 19-20, May 24-25, July 5, July 21, September 6, September 27, October 18, and November 8). In addition, there were numerous trips in August through October during which Bill Farr and Jim Brown set up and dove in Bib Springs (the resurgence for Lilburn Cave) and in the Rise (where Redwood Creek enters Lilburn Cave). Approximately 900' of new survey was done at each of these sites, under difficult conditions of low visibility, cold water, long dives times, and at depths of up to 260' (see report by Bill Farr for more details).

Due to the fact that almost all the easily accessible leads in Lilburn have been pushed and surveyed, there were only ten trips into the cave during which new dry passage was surveyed. Two trips accidentally surveyed passage done late in 1996 that was not marked as being done on the quadrangles they were using. Three other trips were not able to find any unsurveyed passage, although some digging was done on at least one of these trips (near the Carrot Stalactites at A48). Checking of quadrangles was also done on some of the dive tank hauling trips.

Starting at the north end of the cave, a lead in the Kleinbottle Complex was pushed for about 100' to a pinch. Much potential remains in this area, but all leads require digging or total immersion in a watery belly-crawl. Near the beginning of the Crystal Crawl, a team surveyed 270' of vertical maze, reaching an elevation only 50' below the Meyer entrance, and leaving a few leads. This was rather a surprise, as initially the lead was thought to end after 30', but the team was able to push through a tight slot. About 112' of mop-up survey was done in the lower West Stream Complex. Up in the Angel's Perch area above the West Stream, where many discoveries were made in 1996, an additional 145' was surveyed, with a few small leads remaining.

In the Curl Passage, 390' was surveyed, starting in a previously explored passage that went parallel to the Curl, but then crossed over it into virgin passage that choked in flowstone. A trip to the Mud Club area (under the Impossible Dream) first mopped up two leads, then did a short dig to access 300' of new passage, mostly fairly tight. On a return trip, a rock was moved and about 200' of large passage (for Lilburn) was accessed. The passage can be seen continuing past a granite boulder choke.

A trip to the seldom-visited Fallen Soda Straw room found all leads blocked, but did find 25' of unsurveyed passage near the nearby Jefferson Memorial. About 200' was surveyed near the Z room. On the last trip of the year, an attempt to reach the Mousetrack area was foiled when it was discovered that the normally sandy entrance passage was almost filled with water, with a strong cool breeze blowing across it. This likely indicates that a new entrance to the cave has opened up in this area. Several hours were spent digging in a lead near by, leading to 100' of nice sandy stooping passage and another dig. Another lead in this area was checked and found to lead to an upper level complex with large, loose boulders. Beyond these, a canyon was followed heading south for several hundred feet, ending at a pit where a rope is needed, and good airflow was noted. This pit is in a blank part of the map, and only 300' from the known southern end of the cave, so has interesting potential that will have to wait until 1998 to exploit.

Altogether 2280' of new dry passage was surveyed, using 236 stations, with and additional 200' of resurvey. This brings the surveyed length of Lilburn Cave to 26.4 km (16.4 miles). The dry surveyors for 1997 were Lynne Jesaitis (174 stations), Peter Bosted (168), Carol Vesely (75), Brad Hacker (47), Marilee Profitt (46), R. Tyres (44), Roger Mortimer (38), E McGee (34), Jeff Cheraz (34), Mark Scott (30), J. Norman (14), Cindy Heazlit (14), J. Benson (12), and Art Fortini (12).