Dicromantispa interrupta

Dicromantispa interrupta

Sunday, June 14, 2009

Another Floodplain Grotto

On Saturday, Sleazeweasel and I visited some mature limestone hammock and cypress swamps along the edge of the floodplain of Florida's southern Withlacoochee River. The day was hot and humid, and my tee shirt was literally saturated and dripping with sweat by the end of the afternoon adventure. Mosquitoes were so bad that we were compelled to take two cans of repellent along on the dayhike.

Sleaze had previously been there to a group of medium-sized caves and wanted to go back and explore further for more. The upland woods are dominated by live oak, laurel oak and sweetgum, and the floodplain edge wetlands by bald cypress, red maple, sweetgum and popash. Although a mature forest landscape, it is in an arrested successional stage due to periodic logging. Fortunately, cattle are excluded where we wandered.

Of particular delight to me, we encountered a small copse of forest-grown live oaks. Most of Florida's huge live oaks are open-grown; that is, they get their start in life in an open field where sunlight is not limiting, so rather than grow straight and tall they grow upward a few feet and then branch out into several to many limbs that are only the diameter of a Brontosaurus neck. Forest-grown live oaks, however, have to compete for sunlight from Day One, so they tend to have a single stem until they can grow up into the canopy where they branch out. One of the oaks in this stand was almost 4ft in diameter appx 50ft above the ground. Now, that's stolid!

The first karst feature we encountered was a small line of low, stepped rock faces within a first order drainage route that might become small waterfalls during storm events. We took GPS readings and moved on. The second feature was a genuine cave containing appx 60 – 70ft of joint-controlled passageway, all of hands-and-knees height and similar width:

We then came upon the caves that Sleaze had promised at the edge of the floodplain along the base of a rocky scarp. They are formed at the river's normal high water elevation by acidic floodwaters primarily along joints. Some of the caves are formed within rock pedestals that rise above the floodplain sediments, with each pedestal containing one or more caves. The pedestals are less than 100ft across in any dimension, and have heights up to perhaps 20ft. The pedestals are within a short floodplain “valley” that extends away from the floodplain axis.

Most of these caves have two or more entrances picturesquely framed with boulders and bedrock. These offer numerous walk-in entrances, skylights and twilight zones extending ex luce in tenebrum.*

Mosses, liverworts, ferns, vines, and other herbs blanket the soft, moist rock. Here the forest canopy is dominated by deciduous trees, including bald cypress, swamp tupelo, red maple, Florida elm, Shumard oak and sweetgum. Sleaze encountered a cottonmouth on his previous trip, but this time we heard only narrowmouth toads, exotic greenhouse frogs and common birds like the Carolina wren, northern cardinal and northern parula warbler.

I get the impression that this little valley once was a cave formed by a small underground stream that was enlarged at the edge of the floodplain where it discharged into the river. Over time the cave roof eroded mostly away as the rock surface eroded downward and the cave roof dissolved upward. The main passage of the cave is the little valley now, and the caves that remain are all that's left of the original cave.

The total effect is spectacular. Imagine walking through tall trees and a lush, subtropical fernery among hanging gardens draped over rock blocks and cliff walls, with the easiest routes being through well-lit caverns. This is truly a jewel of a spot.

*Note: The University of Florida's motto is ex tenebrum in luce, which is Latin for from darkness into light.

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