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Nature -- Now and Then

Posted: February 4, 2014 4:42 p.m.
Updated: February 5, 2014 5:00 a.m.

Forty Acre Rock

By Austin Jenkins

While several weeks of winter remain, thoughts of spring are swirling in my mind as I ponder the pilgrimages before me. Several will lead to Forty Acre Rock, just a half hour north of Camden. This public property is prolific with reasons to be excited about nature, not the least of which is an expansive and exposed granite rock, full of small craters where interesting plants and animals prevail. Imagine the moon, except with life upon it. My students never fail to be awestruck. After walking around on the rock, they predictably ask how this curious conglomeration of rock and life got here. The answer is found in an amazing story of connections between the geology of the past and the biology of the present.

To understand this, let’s zoom out for a moment. You are probably aware that South Carolina is comprised of several distinct regions. In explaining this rock, we are concerned with the Piedmont, that land with rolling hills of red clay and a few big rocks scattered about.

If we rewind the clock 500 million years, we see the beginnings of continents on the move, in a quest to coalesce into a supercontinent called Pangea.The first collision involved two strands of islands that were pushed into eastern North America. These islands became our Piedmont. In other words, places like Greenville, Spartanburg, Newberry and Lancaster sit upon land that was once out in the ocean and not originally part of North America. Finally, about 300 million years ago, Europe and Africa collided with North America. In addition to delivering our Piedmont, this series of collisions provided a thrust of crust, giving us our Appalachian Mountains. When these collisions occur, magma is manufactured by immense heat and pressure within the Earth. Although it rose and came close to the earth’s surface, the magma in our area remained underground. There, it slowly cooled and formed the rock we now call granite. Geologists suspect these buried rocks were exposed over 100 million years ago after many years of natural soil erosion. This gave us the popular granite exposures in our mountains, such as Ceasars Head and Table Rock, but it also produced those of the Piedmont, including Forty Acre Rock, Flat Rock and several others stretching across the southeast. Since that time, life found fancy ways to work itself onto the rock surface, carving out an existence that amazes me every year I return to this place.

One species with an array of adaptations is a tiny plant with a fitting name, Elf Orpine. It resembles and is related to the "Sedum," or "Autumn Joy" often planted in flower gardens. Elf Orpine lives in the little potholes upon the flat surface of the rock where only a few millimeters of soil are available to hold moisture. When rains come in March, these potholes fill with water for a few weeks until temperatures rise in early April, sucking up any remaining moisture into the air. From then through summer, the whole rock is dry and hot, reaching surface temperatures of 120 degrees and rendering life difficult at best.

Many plants here have condensed life cycles, allowing reproduction to occur during this brief window when water is available. Elf Orpine grows, flowers, and fruits in a matter of only two to three weeks. For insurance, it has succulent leaves like that of the cacti. Soon the pools dry up, and the plant does too. Living life that fast is a smart strategy, but what of the newly formed seeds? In another feat of survival, the seeds are retained at the top of the dead plant. Kept above the scorching surface temperatures of the rock, they are protected. Then, after the dangerous summer heat has passed, the seeds drop. Unlike many seeds, Elf Orpine seeds germinate in the fall, forming a small cluster of leaves. In this way, they are ready for photosynthetic action as soon as spring arrives. If they waited until spring to germinate, it is less likely they would complete their life cycle in time.

This little plant is one of many species specifically adapted to life on these exposed rocks. There is even a grasshopper that eats moss and is perfectly camouflaged to match the grainy appearance of the granite on which it dwells. A lichen spider does the same.

When we think about interactions in nature, they often involve the living affecting the living. For example, one might imagine a bobcat catching a bobwhite, or mistletoe parasitizing an oak tree. However, we don’t often give notice to the nonliving and its effects on the living. It strikes some as surprising that something completely lifeless, like the rock just up the road, affects and even controls something that has life, like the Elf Orpine. If we have considered such connections, it’s most often in the present tense. I think of an ice storm killing plants, or a hurricane toppling trees. We witness the nonliving impact the living in real time. But how often do we consider connections between the present and the distant past? For example, everything about the Elf Orpine is a direct reaction to a continental collision that occurred 300 million years ago. Furthermore, this collision, although in the distant past, is still exerting its control over the present.

That is why the connections between now and then are so incredibly fantastic to fathom, and nature is replete with other similar examples. So next time you walk into the woods, remember this: you are not just walking into the woods of today. You are walking into woods with whispers of yesterday. If you listen well, the plants and animals have stories to tell, timeless tales providing us with a view full of more history than we ever knew.


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