South Mountain is part of the Blue Ridge mountain range, which formed over 370 million years ago as part of the Acadian Orogeny. Over the past several million years South Mountain has been eroding away which is actually an incredible phenomenon. During the event of erosion many different events are happening at the same time. Weathering is once part of the erosion process and is caused by; rain, snow, ice and river water movement that erodes the soil and rock thus causing rocks to tumble down the mountainside, some striking other rocks and setting them into motion, while others block waterways to create ponds, or even create new waterways. Another event that is also taking place is exfoliation. Exfoliation is when weathering occurs mainly in granitic rocks where over time temperature differences in the surface and subsurface of the rock caused by heat and cold can cause minute cracking which over time is effected by mechanical and chemical weathering. Over time the gap between the layers of rock grows and eventually the two pieces of rock separate. We saw this first hand on the side of the mountain at a place called Hugo Rock where during hurricane Hugo an immense section of rock separated from itself.
South Mountain is made up of many different types of materials such as igneous, sedimentary and metamorphic rock. We saw things like feldspar, mica and quartz metagraywacke and conglomerate. An interesting piece of geological history is metagreywacke. Metagreywacke, which is an underwater sedimentary rock, is above ground here at South Mountain this makes one ponder the question” was this area at one time once underwater?”
The waterfalls we saw were impressive, not only could you see where the flow had worn away at the rocks with the sheer volume of water moving though them, but the rivers and streams that flowed down the side of the mountain showed how over the years the waterways have changed not only direction but how it had moved these massive rocks. By looking at where the water had pushed against the rocks it made pools by eroding away sections, we could also see small indentions in some rocks like someone had carved a bowl or something Dr. Pillar explained that this was where once a pebble or small stone had once been and over the years the water had worn away the softer material and the material trapped inside washed away.
Even after seeing everything I saw on this trip it’s hard to believe that this mountain was not always a mountain, that it was level ground that is slowly being worn away by nature and overtime has become an ever growing/changing mountain.