Where Did All These Rocks Come From?
Walking along the meadows and through the wooded areas of Harmony Hill, one can’t help but notice the large rock outcrops that dot the landscape. In some places, a rock will pop up here and there. While in others, the rocks dominate the view and force streams to flow around them. No matter if small or large, the granite of the piedmont dictates the flora and fauna of Harmony Hill and, like everywhere else, is the base and the backdrop of the story of the land.
It isn’t uncommon to see a beautiful rock jutting from the ground and want to step atop it to achieve a better view of the surrounding area. That desire is imbedded in us as a species, looking to survey from higher ground and get an understanding for what may be out of our normal field of vision. With that in mind, we look to stand upon the geology of Harmony Hill to get a better grasp on what is here and what we could expect to be here as we look forward.
People new to the area often see rocks in the piedmont and ask, “How on earth did those rocks get here?!” One of our favorite professors would often cite their favorite geology professor and tell of the lessons of “the was-ness of the is”. That is, looking at what is before you will give you a great bit of insight into what was once here. When we look at the granite found so prominently in places on Harmony Hill today, we are provided a time machine that tells us how they were formed and how “they got here”!
We frequently mention the “Piedmont”. Well, what does that mean? Piedmont literally means “foot of the mountain”, telling us we are not in the mountains; but, just down from them. While we aren’t in the mountains, Harmony Hill was created in the same time frame as the mountains and the geology we enjoy is a product of the same geologic activity. What activity, you ask?
To get that perspective, we need to back up a little bit. Actually, we need to back up A LOT! We must back up some 300 million years to begin getting the perspective we need! The continents as we know them now did not exist. The great supercontinent, Pangaea, included almost all of the continental crust we know today that makes up the seven modern continents. Somewhere around 250-300 million years ago, movement began in what would see the transition from Pangaea, Gondwanaland and Laurasia to Africa, Antarctica, Asia, Australia, Europe, North America and South America. Through the coalescing and opening of oceanic crust in the Wilson Cycle, these land masses moved around, violently collided (sometimes repeatedly) and separated.
North America, as part of a section of Europe, collided with what we now know as Africa more than once. With this “triple collision” a number of things resulted. One of the more notable results was the formation of the Appalachian Mountains, that extends from Alabama, through the eastern US and up into southeastern Canada. This collision lifted the now rolling Appalachians to elevations that rival (or even rose above) the Himalayan Mountains. Being about 220-250 million years older than the Himalayas, the Appalachians are now a mere mound of their former selves. Beautiful nonetheless, the sheer age of the range has caused them to erode down to the considerably lower elevation we see today, with the tallest peak, Mt. Mitchell, being just 6684’ above sea level.
Closer to Harmony Hill, another exciting geologic event was happening. The great compression between land masses that lifted the Appalachian Mountains was squeezing an arc of islands, once adrift in an ancient ocean, into the southeastern coast of modern North America, forming much of the piedmont of today. This compression not only cemented this chain of islands onto North America, but also caused a great deal of magma to form and bubble below the surface of the earth. The sheer pressure alone caused tremendous heat that liquified and even altered the rock formations here, causing metamorphic granite to become a dominate rock formation. Milky quartz can also be found all along the piedmont, as can other quartz, like smoky quartz.
This large area of magma cooled at various rates, causing some granite formations to be solid and stable, while others formed larger crystals and are less stable. This flaky granite is not sought after for its structural qualities, but it does break down into soil more readily, giving some of the soil at Harmony Hill a sparkle of quartz, feldspar and mica (the minerals that make up granite).
About 100 million years ago many of these granite formations began to show, as the overlying geologic formations and soil eroded away. The granite left exposed is harder than the softer sedimentary rock and even the less stable metamorphic rock surrounding it. This ability to withstand erosion over time has given Harmony Hill everything from small granite outcroppings, about the size of a football, to larger areas that resist moving water and give us seasonal waterfalls down rock faces. And we enjoy seeing each of them.
This walk down memory lane is not just for the sake of looking back. To know what plants are here, thereby knowing which insects, reptiles, birds, mammals, etc. are here, we must know our geology. Our geology gives us the creation of our soils, which dictate the rest of the residents, both plant and animal, we should see and expect. You see, by looking back at what WAS, such as the compression of islands into North America, we can get a better idea of what IS, such as the wild gingers, swamp azaleas and milkweed vines we have this summer. The was-ness of the is surrounds us and it tells us not just what is here now, but what was happening 300 million years ago.
By walking atop a granite rock at Harmony Hill and looking out over the hardwoods below, we are not only looking out at a different habitat, but we are also able to look back to a different time. A time when Earth looked remarkably different. A time that gave us ancient mountains and cooling magma below the surface. A time that gave us Harmony Hill. And we celebrate that every day.