The quaternary paleontology and paleoecology of crystal ball cave, millard county, utah: with emphasis on the mammals and the description of a new species of fossil skunk



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Important Notice!

Crystal Ball Cave contains cave formations and vertebrate fossils that are protected by federal law. Mining claims being sold in the area confer absolutely no rights to these protected resources, and any mining activity would require a mitigation plan to insure their protection. There is no significant quartz or ore deposits in or near the cave as claimed in the eBay the auction. The cave is in sedimentary rock composed of unusually pure limestone. Also, the mining claims confer no right fence off or restrict access to the site. A KSL-TV article about this controversy can be viewed at http://www.ksl.com/?nid=148&sid=7412960. An article about Crystal Ball Cave can be found at http://desertislands.org/crystal_ball.htm.

 

Great Basin Naturalist, vol. 45, no. 3, pp. 337-390 (1985).


Introduction
Geology of the Cave
Methods
Antiquity of the assemblage
Paleoecological Setting

Systematic Paleontology
Mammals
Rodents
Carnivores
Ungulates

Conclusions
Acknowledgements
References Cited
Figure Captions
Table Captions


THE QUATERNARY PALEONTOLOGY AND PALEOECOLOGY OF CRYSTAL BALL CAVE, MILLARD COUNTY, UTAH: WITH EMPHASIS ON THE MAMMALS AND THE DESCRIPTION OF A NEW SPECIES OF FOSSIL SKUNK

Timothy H. Heaton

Department of Geology, Brigham Young University, Provo, Utah 84602

ABSTRACT

Crystal Ball Cave is located in a small outlier of the Snake Range in Snake Valley 1 mile (1.7 km) from Lake Bonneville at its highest level. Original vertebrate skeletal material (mostly mammalian) is found in shallow dry dust 200 feet (61 meters) inside the cave. Radiocarbon dates show that fossils have been accumulating since at least 23,000 Y.B.P. It appears that wood rats and possibly small carnivores transported the fossils into the cave because only the smallest elements of large mammals are represented.

The fossil assemblage represents a much more boreal community than the present local fauna. Fish, Ondatra zibethicus, and Mustela cf. vison, which require perennial water, were recovered, as were Ochotona princeps, Lepus cf. americana, Microtus cf. pennsylvanicus, Vulpes vulpes, and Martes americana, which have also been extirpated from the Snake Range. Marmota flaviventris, Neotoma cinerea, cf. Cervus elaphus, and Ovis canadensis were recovered but now occur only at higher elevations in the range. Extinct taxa recovered are Smilodon cf. fatalis, Equus species, Camelops cf. hesternus, Hemiauchenia cf. macrocephala, cf. Symbos cavifrons, and a new species of Brachyprotoma, herein named B. brevimala. This is the first recovery of Brachyprotoma from the western United States.


INTRODUCTION

Crystal Ball Cave is located 3 miles (4.8 km) northwest of the town of Gandy, Utah and 0.6 miles (0.9 km) east of the Utah-Nevada border (Sec. 30, T15S, R19W, Salt Lake Base Line and Meridian) in the northeast side of Gandy Mountain, a small outlier on the northeastern edge of the Snake Range (see figures 1 and 2). The cave is at an elevation of 5775 feet (1760 meters), 644 feet (195 meters) above Lake Bonneville at its highest level (see Currey 1982, Gilbert 1890), and has about 500 feet (150 meters) of passage and a floor area of about 20,000 square feet (1860 square meters). Calcite crystals and speleothems cover most of the cave walls and floors, but some shallow sediments are present which contain locally abundant unaltered vertebrate fossils.

It is uncertain if native Americans knew of Crystal Ball Cave, for no ancient human artifacts were found in this study. The cave was discovered by the late George Sims of Gandy in February, 1956. He found the original 3 foot (1 meter) diameter entrance that leads into a large chamber (see figure 3). The original east entrance was enlarged, the north entrance was blasted out through a soil-filled passage at the other end of the cave (see figure 3), and other improvements were made by Cecil R. and Jerald C. Bates of Gandy, Utah and Thomas E. Sims of Elko, Nevada (J. C. Bates 1983 personal communication).

Herbert H. Gerisch and Robert Patterson collected bones from Site 1 (see figure 3) in 1956 that they donated to the Los Angeles County Museum (H. H. Gerisch 1983 personal communication). Later Michael Stokes of the Los Angeles County Museum collected additional specimens from Site 1. These early collections consisted of float only and included bones of extinct horses and camels. On at least one of these early expeditions, some specimens were also collected from Gandy Mountain Cave, a smaller cave that lies about 1/4 mile (0.4 km) south of and 100 feet (30 meters) higher than Crystal Ball Cave. Specimens from these two caves are indistinguishable in the Los Angeles County Museum collection because the cave in which each specimen was recovered was not recorded. I dug several test pits in Gandy Mountain Cave in 1981 and found preservation to be poor and specimens to be few and probably all Recent. So although some specimens were collected from Gandy Mountain Cave, they are not considered in this study, except some which may be among the Los Angeles County Museum collection.

The first extensive collecting in Crystal Ball Cave was done in 1977 by Wade E. Miller and his students from Brigham Young University who used fine screens to obtain thousands of specimens (all from Site 1). Miller (1982) described this investigation and listed the genera identified in a report on vertebrate fossils from Lake Bonneville deposits. Wade E. Miller and I operated similar collecting projects in 1981 and 1982 (Sites 1, 2, and 3), and I wrote a preliminary report on this study (Heaton 1984). Crystal Ball Cave is Los Angeles County Museum locality 4534 and Brigham Young University vertebrate paleontology locality 772; the specimens from the cave are cataloged as LACM 123655-123711 and BYUVP 5300-8888, 8911-8933. Taxa recovered are listed in table 1.

The Crystal Ball Cave assemblage is the first late Wisconsinan age fauna to be described from the state of Utah. Although Utah has extensive Pleistocene deposits from Lake Bonneville, surprisingly few vertebrate fossils have been recovered from them (Miller, 1982). The only other Pleistocene assemblage that has been described from Utah is the Silver Creek fauna of north-central Utah, 14 miles (22 km) east of and 1,200 feet (360 meters) above Lake Bonneville's highest level and of late Sangamon to early Wisconsinan age (Miller 1976).

The nearest described Pleistocene vertebrate localities are four shelters located in Smith Creek Canyon, White Pine County, Nevada, 9 miles (14 km) south of Crystal Ball Cave. New species of mountain goat (Stock 1936), eagle (Howard 1935), and gigantic vulture (Howard 1952) were described from Smith Creek Cave, the primary site. Literature on the Smith Creek Canyon sites includes a description of the avifauna by Howard (1952), the micromammalian fauna by Goodrich (1965), the herpetofauna by Brattstrom (1976), the whole fossil assemblage by Miller (1979) and Mead et al. (1982), and the archaeology by Bryan (1979), Harrington (1934), and others. Although the Crystal Ball Cave fauna is chronologically and geographically close to that of Smith Creek Canyon, it differs in having its fossils deep in the cave, and this has resulted in significant differences between these assemblages. Crystal Ball Cave, for example, has more abundant mammal fossils but less abundant bird fossils than the Smith Creek Canyon sites.

The Crystal Ball Cave assemblage contains only small bones with a maximum length of about 10 cm and maximum weight of about 50 grams. This has caused some problems in identifying the large species since only the smallest elements, which have rarely been considered in other studies, are represented. The assemblage, however, is very large and is important since few assemblages of late Pleistocene age have been reported from the region. The size of this assemblage and the time restraints upon the project have limited the depth to which each taxon could be studied. For taxa with large numbers of specimens, only the best specimens were considered. Additional work could turn up more species, and statistical studies on the more abundant taxa could yield much additional information.


GEOLOGY OF THE CAVE

The Snake Range is a north-south trending Basin and Range horst composed of early Paleozoic rocks. Gandy Mountain, where Crystal Ball Cave is situated, is an outlier of this range (Gilbert 1890, Nelson 1966). The cave lies in unnamed Middle Cambrian limestone on the upper plate of the Snake Range Thrust Fault, which is exposed at the north and south ends of Gandy Mountain (Nelson 1966). The massive beds around the cave strike N35W and dip 20NE (Halliday 1957), following the local trend throughout Gandy Mountain (Nelson 1966). The limestone is cavernous and contains many small solution cavities, in addition to Crystal Ball and Gandy Mountain Caves.

I have recognized four distinct stages of the cave's history: 1) a period of dissolution of limestone to form the cave, 2) a period of precipitation forming a layer of large calcite crystals ("nail head" spar) up to 1 foot (0.3 meters) thick on the cave walls, ceiling, and floor, 3) a period of partial dissolution of these crystals in the upper portions of the cave, the appearance of joints that cut the large calcite crystals, and the dislodging of breakdown from the ceiling of the large entrance room, and 4) the formation of vadose calcite speleothems and influx of sediment and fossils from outside the cave.

The beginning of stage 1, the dissolution of the cave, is of uncertain date. Davis (1930) demonstrated that limestone dissolution to form caves occurs predominantly in a thin zone just below the water table which is rich in carbon dioxide from groundwater percolating down from the surface. Once it reaches the water table, this groundwater dissolves the rock as it moves very slowly down the water table slope (Davies 1960). This appears to be the case in Crystal Ball Cave, since no scalloped or stream-cut passages are present to suggest the presence of fast-moving water expected in an above water table origin (Malott 1938, Myers 1969). The cave tends to parallel the strike of the beds and is relatively horizontal, as would be expected if the cave were formed at the water table. Green (1961) cited evidence that some caves in western Utah predate the tilting associated with the Basin and Range uplift. The fact that Crystal Ball Cave is roughly horizontal and parallel to the strike of the beds suggests that it postdates this tilting. But since the cave is high in a small isolated hill, considerable uplift and/or erosion must have taken place since the cave was at the water table. The cave does not parallel the present land surface as the water table tends to do (Myers 1969), and this further suggests that much overburden has been removed since the original dissolution of the cave.

Stage 2, the precipitation of large calcite crystals, represents a different groundwater environment than the preceding dissolutional stage. It is generally agreed that such "nail head" spar forms in still, calcite-saturated water where nucleation centers are free to grow into large euhedral crystals (Hill 1976). This shift from dissolution to precipitation does not necessarily represent a significant change in the level of the water table, but it does represent the drastic reduction in the carbon dioxide content of the groundwater necessary for calcite precipitation (Moore and Nicholas 1964). Several vertical cavities (domes) extend upward into the cave ceiling, and these predate the calcite precipitation because they are partly filled by it. Moore and Nicholas (1964) cited evidence that such domes form late in cave dissolution and provide more direct water and air connections to the surface. Myers (1969) stated that they are of vadose (above water table) origin and caused by vertical seepage. Perhaps the formation of these domes allowed gas exchange between the groundwater in the cave and the surface permitting carbon dioxide to escape and calcite to be precipitated.

Stage 3 includes several events which are not chronologically separable. Some of the calcite crystals in the roof of the cave are completely dissolved, and locally some of the limestone bedrock underneath it is also. This is especially evident in the aforementioned domes. Joints and breakdown, both of which cut the previously formed calcite crystals, probably represent one or several earthquakes. If any uplift postdates the cave's origin, it probably occurred during this stage. These cracks and breakdown blocks were later filled and covered by the speleothems of stage 4, showing their chronologic relationship.

Stage 4 postdates the loss of voluminous standing water in the cave and the opening of entrances large enough to allow considerable gas exchange and sediment into the cave. Vadose speleothems such as the stalactites, columns, and rimstone pools found in Crystal Ball Cave form subaerially in caves having enough gas exchange with the surface to allow carbon dioxide to escape from the dripping groundwater (Moore and Nicholas 1964). Near the east entrance of the cave some small columns have formed upon and been partly covered by sediment coming in from the entrance, showing the concurrence of these events. The vertebrate material under study entered the cave during stage 4 when cave opening(s) were sufficiently large to allow their entry and dry conditions allowed their preservation; therefore cave stages 1 through 3 predate the oldest fossils.

Twelve sediment samples were collected at sites throughout the cave and screened to determine the degree of sorting. All samples are poorly sorted, but samples farthest from known entrances tend to have a higher percentage of fine particles. Particles under 0.0024 inch (0.061 mm) in diameter make up over half the weight percent of three such samples. Samples were placed in hydrochloric acid to remove all calcite. Sediment from Site 1 (see figure 3) is composed of about 80% calcite and 20% very fine but poorly sorted clastic grains, namely quartz, mica, and an unidentified ferromagnesian mineral. Larger clastic grains were found in samples closer to each entrance and comprised greater portions of the sediment.

The calcite portion of the sediment is composed of both crystal fragments, probably derived from broken "nail-head spar," and cryptocrystalline caliche-like crust associated with clastic fragments, almost certainly precipitated in the cave. The clastic fragments could have been washed in, blown in, brought in by animals, or been released from the cave walls as impurities in the limestone. The sediments at Site 1 show no sign of ever having been wet except in some areas where they have been cemented with calcite. But water runs in through the east entrance during storms filling the large entrance chamber with mud. Wind gusts can be quite strong through the cave during storms, but only because the north entrance was opened by man. The importance of these factors is difficult to determine, but the fact that the bulk of the sediment far inside the cave is calcite demonstrates that the sediments are mostly derived from within the cave by weathering of the limestone and calcite crystals rather than from outside sources.
METHODS

The dry, dusty sediments of Sites 1 and 2 are composed of nearly 10% vertebrate bones by volume. These fossiliferous sediments are unstratified and never more than 1.5 feet (0.5 meters) thick, so no meaningful relative dating is feasible. Collecting was done mainly at Sites 1 and 2, but a few specimens were taken from Sites 3 and 4 (see figure 3). No significant differences were found between fossils from the various sites, so the site at which each specimen was collected is not reported here but can be found in the Brigham Young University Vertebrate Paleontology Laboratory catalogs.

On early collecting trips most of the field time was spent digging through the sediments and collecting specimens by hand. Sediment was also taken to the lab in bags and screened in order to recover smaller bones and teeth. After using this method for several trips, the collection had overwhelming numbers of rodent and lagomorph fossils, but bones of larger mammals were few. So on the last collecting trip large volumes of cave sediment were screened inside the cave with a coarse screen, and the number of larger bones in the collection was thereby more than doubled.

Little laboratory preparation was necessary with the larger Crystal Ball Cave fossils. A few required removal of hardened dirt or calcite. All were washed to remove dust. Considerable time was spent manually separating small bones and teeth from cave sediments. This was done in the laboratory with forceps after the sediments had been washed through a fine screen and allowed to dry. Approximately 35 cubic feet (1 cubic meter) of cave sediment was prepared in this manner, and virtually all the bone was removed.

Because of the great abundance of small mammal fossils recovered, only the skulls and jaws were studied. All identifiable material was used for larger mammals because they were not as well represented and because few dental elements were recovered. Identification was made by comparison to Recent specimens housed at the Brigham Young University Monte L. Bean Museum, fossil specimens housed at the Brigham Young University Vertebrate Paleontology Laboratory, and by extensive use of the literature.

Small living mammals were captured inside Crystal Ball Cave and around Gandy Spring at the base of Gandy Mountain. This trapping was not extensive, but it did indicate what species are abundant in and around the cave. The species trapped are recorded in table 1. Jerald C. and Marlene Bates of Gandy (1983 personal communication, 1984 personal communication) were interviewed for additional information about the modern local fauna and recent history of the cave including modification by man.


ANTIQUITY OF THE ASSEMBLAGE

One problem with the Crystal Ball Cave assemblage is that it is impossible to separate fossil bones from Recent bones using superposition, because the sediments in which they are found are shallow and unstratified. Some of the best specimens of extinct species were found on the surface by early expeditions. The cave seems to have been accumulating fossils continuously from some date in the past, when an entrance was formed, until the present. The purpose of radiometric dating was to establish when fossils were first deposited and if the rate of fossil deposition has been uniform since then.

Four bone samples were sent to Geochron Laboratories, Cambridge, Massachusetts, for carbon-14 dating. Because of the small size of bones in the assemblage, these samples (which included some of the largest recovered) were just over 25 grams, the minimum weight suggested for dating. Two were of small extinct horses: a thoracic vertebra (BYUVP 7687) and a distal metapodial epiphysis (BYUVP 7568); and two were fragments of unidentified limb bones of large mammals. Geochron Laboratories cleaned and washed the four samples in acetic acid to remove adhering materials then crushed them and soaked them in agitated acetic acid for 24 hours to remove normal carbonates. The samples were then hydrolized under vacuum with hydrochloric acid to dissolve bone apatite and evolve its carbon dioxide for collection. The carbon dioxide samples were converted to methane and counted in a low background beta counter (with C-13 correction), and dates were based on the Libby half life (5570 years). The ages reported are listed in table 2. The oldest date of "over 23,000 Y.B.P." was given because no C-14 was detected in that sample.

The oldest date of 23,000+ Y.B.P. gives a minimum age for the time fossils first entered the cave. The youngest horse bone date of about 19,000 Y.B.P. gives a maximum age for the loss of that species from the area, although other studies have shown that small horses lived beyond 10,370 Y.B.P. in Idaho and until about 8,000 Y.B.P. in Arizona and Alberta, Canada (Kurten and Anderson 1972, 1980, Martin 1967). Otherwise the four dates give only a general age for the assemblage and provide no information about the antiquity of individual taxa. The fact that all four dates are over 12,000 Y.B.P. suggests that bones, at least of large mammals, may have been deposited more frequently during the late Pleistocene than during the Recent. If so, this could be due to a greater abundance of the animals themselves, a change in what animals (or other processes) deposited the fossils, or the former presence of larger or additional entrances.

Thirty radiometric dates have been reported from the Smith Creek Canyon sites (Thompson 1979, Thompson and Mead 1982, Valastro et al. 1977), and they demonstrate that accumulation of fossils there was concurrent with fossil deposition at Crystal Ball Cave. The two oldest Smith Creek dates are 28,650 Y.B.P. (Smith Creek Cave) and 27,280 Y.B.P. (Ladder Cave), which correlate well with the date of "over 23,000 Y.B.P." from Crystal Ball Cave. The other 28 Smith Creek Canyon dates are younger than 18,000 Y.B.P. with the majority being from 10,000 to 13,000 Y.B.P. The mean age of the four dated Crystal Ball Cave specimens is considerably older than the mean age of dated specimens from any of the Smith Creek Canyon sites, suggesting that its major period of fossil deposition was earlier; but a sample size of four dates is not statistically significant enough to demonstrate this.
PALEOECOLOGICAL SETTING

The Pleistocene-Recent boundary was a period of intense climatic and faunal change. The changes at this fossil site were particularly drastic due to its close proximity to Lake Bonneville which was present during most of the time that fossils were being deposited. According to Currey (1982) the Bonneville Level terraces at Gandy are at an elevation of 5165 feet (1565 meters), showing that the lake rose to 644 feet (195 meters) below and 1 mile (1.7 km) east of Crystal Ball Cave and filled Snake Valley as far as 36 miles (60 km) south of the cave (see figure 1). My previous statement that Gandy Mountain was once an island in Lake Bonneville (Heaton 1984) was based on data from an earlier study and is unconfirmed. Lake Bonneville started its last cycle of filling prior to 26,000 Y.B.P., and it reached its highest level (Bonneville Level) about 16,000 years ago (Currey 1982, Scott et al. 1983). The lake remained at the Bonneville Level until 14,000 or 15,000 Y.B.P. when the flood at Red Rock Pass, Idaho dropped the lake to the Provo level, where it remained until about 13,000 Y.B.P. (Currey 1982, Scott et al. 1983). At the Provo level the lake had only a shallow arm extending southward into Snake Valley to a point 5 miles (8 km) east of Crystal Ball Cave (Currey 1982). Further lowering of the lake after 13,000 Y.B.P. caused its quick retreat northward out of Snake Valley to a point 40 miles (65 km) northeast of the cave by 10,300 Y.B.P. (Currey 1982). Based on these dates Lake Bonneville was very close to Crystal Ball Cave for at least half the time that fossils were being deposited and within Snake Valley for about two-thirds of the time or longer. Then within a few thousand years, the fossil site changed from being near the shore of a large continental lake to being in a dry desert, as it is today.


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