A General Introduction to Bat Cave

Overview

Bat Cave is, of course, a cave, one of the common features found in areas dominated by karst processes. There are over 150 such caves throughout Alachua County. Many, if not most of them, are below the water table and are therefore filled with water. Bat Cave was originally owned by Jefferson Smurfit Corp., a paper company based in Illinois, which transferred ownership to Santa Fe College in 1994. Since that time, SF has fenced off the five entrances to the cave, removed 2 tractor trailers full of garbage from the cave and surrounding area, and cleaned the graffiti from the cave walls. The cave is now an educational facility.

What is a cave?

To many of us, a cave is a dark, dank, mysterious underground opening that makes most of us just plain nervous. Nor are we the only people to think that way. Through out time and history, caves have been places of mystery, danger or even death. For example, to the Greeks, a cave marked the entrance to the kingdom of Hades, the underworld where souls went; and its entrance was guarded by Cerberus, the many-headed dog. It is in a cave that Saul consulted the witches of Endor; and to the Maya, caves and sinkholes were the entrances to the underworld, a place to communicate with spirits and the gods of the night...In Viking mythology the entrance to Hel, the kingdom of the Dead was also through a cave.

In reality, a cave is a naturally formed underground open area or chamber, or series of chambers large enough for people to enter. The term cave is often used interchangeably with cavern. Caverns are usually thought of as large systems of caves or a series of large chambers within a cave. Some caves are small, while others include enormous chambers, hundreds or even thousands of feet wide and high. Many caves are shallow but some cavern systems may extend down to more than a mile below the surface.

What kind of Cave is Bat Cave?

Bat Cave is a Solution Cave. The karst features at Bat Cave formed slowly and gradually as the joints in the limestone were enlarged by solution. In some places in the cave, the rocks did settle and collapse. In several places, the cover material washed into the cavern along the enlarged joints and the solution pipes in a process called raveling. Usually, a change in the water elevations in the aquifer leads to raveling. In the case of Bat Cave, most likely an episode of drought led to a lowering of the water table, and, once the solution pipes and the enlarged joints became connected to the cavities in the limestone below the water table, the loose surface materials, mostly sands, began to infill the caverns.

What does Bat Cave look like?

This is a plan view of Bat cave made by the Florida Speleological Society.

How and When Was Bat Cave Formed?

After the Miocene, when the Hawthorne Formation had been removed by erosion and the sands had been redeposited on the top of the Limestone, water percolating to the limestone began to form cavities and enlarge the joints.

Continued solution enlarges these voids . Surface solution also begins to create solution pipes and enlarge the joint patterns. No doubt, some of the surface materials wash into the drowned cave.

As the water table drops, the cave is now mostly dry. The water table is still higher than the lowest portions of the cave most of the time. Those places form the pools that we see in the cave. By now, surface solution has deepened the pipes to the point where they breach the roof of the cave, and surface materials wash into the cave.

When did this happen? No one knows for sure. Given what we know of the geological history of the area, we can reasonably state that the solution cavities in the limestone were not created before the Hawthorn sands and clays were removed from the area by erosion, a process that began in the Late Miocene. Likely the formation of the cave itself dates back to at least the Pleistocene, but more probably to the Pliocene.

The time when the connection between the solution pipes and the cave was established is in greater doubt. In some cases, this appears to have been a fairly recent occurrence (geologically speaking). At the base of one of these solution pipes, we have found some remains of a white-tailed deer mixed in with sediments that washed into the cave. These bones have not been completely mineralized, which commonly happens within a few hundreds of years. Unfortunately this only tells us at least how long that particular pipe has been open. It certainly could have been open for a time before that deer fell in or was washed in. Other pipes may be much older, and some do not show an open connection to the cave yet.

Life In and Around Bat Cave

Before it was cleared for farming and ranching, the area surrounding Bat Cave was originally a mixed southern hardwood forest, dominated by oak and hickory. Today, open fields stretch on either side of the road to the cave. In the immediate vicinity of the property, and on the surrounding acreage, the land was used for sylviculture, the intensive growing of slash pine, Pinus palustris. Growth of competing species was suppressed and the only diversity is in the understory species where native shrubs (especially saw palmetto, Serenoa repens) and ferns can re-establish themselves between periodic discings and burns. On the site proper, the immediate cave vicinity has not been planted for obvious reasons and several species of hardwoods, notably live oak (Quercus virginiana) and wild cherry (Prunus serotina) have been able to establish themselves.

The cooler and damper microclimate near the mouth of the cave supports the growth of several fern species not found on the woodland floor. The lack of sunlight prevents photosynthesis (and therefore primary production) within the cave itself, and vegetative growth is limited to fungi and molds.

Organisms that are found in caves fall into several categories. Some are occasional, some are transients such as bats, others are permanent residents that make a living by feeding on decaying vegetative and animal matter. Some do not make caves their habitat and have fallen or slid into the cave and are trapped, unable to get out.

The transients

Most notable are the bats who use the cave for shelter because of the constant conditions found in the cave. Today there are few bats roosting in the cave. At the turn of the century, many more made the cave their home. They were killed or driven out by vandalism and parties, much to the delight of the mosquitos and other flying insects of the surrounding area.

Occasionally owls also roost in caves and owl pellets, both recent and fossilized, provide us with a great record of small mammals that otherwise would rarely be seen.

The residents

• Cray fish: there are at least 13 species of crayfish adapted to underground life (Hobbs and Franz 1986) 
• Fish 
• Crickets

The unfortunates

Among them we can list a white tailed deer (Odocoileus virginianus) who was trapped in the cave and whose fossilized remains can be found in layers of sand and clay that washed into the cave from one of the pipes.