THE GEOLOGY OF PANAMA ROCKS
Roughly one half-mile long and 60 feet high, the Panama Rocks formations are one the largest exposed examples of glacier-cut, ocean-quartz conglomerate in the world.
The history of the rock formations date back about 400 to 350 million years ago (Ma), during the Devonian period - this is about when trees started to appear in the geologic record (the first mammals appeared about 225 million years ago and modern humans (Homo sapiens) are believed to have originated about 200,000 years ago). Panama Rocks is as old as the first trees, older than the dinosaurs, and three-times older than Half Dome in Yosemite!
In the middle Devonian (385Ma) the landmass that makes up the core of the North American continent was rotated 90 degrees (what now faces east then faced south) and straddled the Equator. Most of the area that forms modern day upstate New York, western Pennsylvania, eastern Ohio, and Lake Erie was a shallow inland sea known as the Appalachian Basin. Panama Rocks was formed from the stones and gravel that made up the shores and bottom of the basin.
About 347Ma the late Devonian extinction occurred and about 50% of all genera went extinct (late Devonian extinction).
The history of the rock formations date back about 400 to 350 million years ago (Ma), during the Devonian period - this is about when trees started to appear in the geologic record (the first mammals appeared about 225 million years ago and modern humans (Homo sapiens) are believed to have originated about 200,000 years ago). Panama Rocks is as old as the first trees, older than the dinosaurs, and three-times older than Half Dome in Yosemite!
In the middle Devonian (385Ma) the landmass that makes up the core of the North American continent was rotated 90 degrees (what now faces east then faced south) and straddled the Equator. Most of the area that forms modern day upstate New York, western Pennsylvania, eastern Ohio, and Lake Erie was a shallow inland sea known as the Appalachian Basin. Panama Rocks was formed from the stones and gravel that made up the shores and bottom of the basin.
About 347Ma the late Devonian extinction occurred and about 50% of all genera went extinct (late Devonian extinction).
The Earth's landmasses came together about 250 Ma and formed the super-continent known as Pangaea. As Pangaea formed, tectonic plates pushed together and the land beneath the Appalachian Basin rose, which slowly drained water from the basin in large, meandering rivers (320-310Ma). These river water carried sand, stone, and sediment from central New York through the eastern part of the State and into north-central Ohio.
While the overall direction of the river was flowing Wast from Central New York to Northern Ohio, the formations at Panama Rocks (and almost all similar formations) run North-South. Because rivers naturally flip over stones in the direction of the current, a process called imbrication, we can actually tell the direction the current of this ancient river flowed. The pattern of imbrication at Panama Rocks today shows that the current where the rocks were deposited actually ran South to North in modern-day orientation. This is likely due to both a bend in the river and the rotation of tectonic plates over hundreds of millions of years.
While the overall direction of the river was flowing Wast from Central New York to Northern Ohio, the formations at Panama Rocks (and almost all similar formations) run North-South. Because rivers naturally flip over stones in the direction of the current, a process called imbrication, we can actually tell the direction the current of this ancient river flowed. The pattern of imbrication at Panama Rocks today shows that the current where the rocks were deposited actually ran South to North in modern-day orientation. This is likely due to both a bend in the river and the rotation of tectonic plates over hundreds of millions of years.
River Current Flips Stones
Pattern of Imbrication at Panama Rocks Today
During the Devonian, animal life was just emerging from the seas and the first forests were beginning to spread over the Earth. Primary life forms were corals and marine mollusks. There are very few fossils in the Panama Rocks, likely because water flowing through the river that deposited the sediment had a relatively strong current and the marine animals that lived at this time were not strong swimmers. We can tell this because the conglomerate rock was washed clean of most of lighter mud, silt, and sand by the current; however, brachiopod, radiolarian, crinoid, and syringopora fossils can be found in clay deposits in Panama Rocks (likely created by eddies in the river).
As the Appalachian Basin fully drained, calcite, a naturally occurring mineral that bound the river stone and sediment together, like a natural concrete, creating the formations at Panama Rocks. This type of rock is known as "quartz-conglomerate", and it is sometimes referred to as "pudding stone” or "Panama Conglomerate." Stones embedded in this rock are oval and rather flat, due to river and wave action smoothing them out. The most common embedded stones are quartz (white), spar (pinkish amber) and flint (tan).
As the landmasses continued pushing together, the Appalachian and Allegheny mountains formed and tectonic plate shifts caused earthquakes, or seismic waves, that fractured the rock into the large "blocks" guests see at the park today.
In this era the Earth's most severe extinction event occurred, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct in the Permian–Triassic extinction event.
Approximately 165Ma, there was major geological activity on what are now the East and West coasts of North America. It is believed that the formations which became Panama Rocks were slowly raised to their present altitude (1650 feet above sea level) at this time. After the rock layer had been fractured, the seepage of water through overlaying sediments carried minerals (iron, lead, etc.) in solution, and it deposited them in the fractures in the rock below. Native Americans obtained lead from a site in the rock formation and sold it to settlers. In 1985, pieces of naturally formed lead were found in the park.
The continents began to move into their current positions about 65 million years ago. Around this time there was a massive extinction of most plant and animal life, likely from one or more catastrophic events, wiping out dinosaur life (Cretaceous-Tertiary extinction event).
About 80,000 years ago North American began to be covered by massive glaciers, starting the Ice Age, which peaked about 26,000 years until about 19,000 years ago. As the glaciers formed and withdrew in alternating advances and retreats, they carved valleys and hills into the land. This process created the valley where the Village of Panama now sits, scraping against the hill where Panama Rocks are located, and exposing the rocks for the first time in millions of years.
The continents began to move into their current positions about 65 million years ago. Around this time there was a massive extinction of most plant and animal life, likely from one or more catastrophic events, wiping out dinosaur life (Cretaceous-Tertiary extinction event).
About 80,000 years ago North American began to be covered by massive glaciers, starting the Ice Age, which peaked about 26,000 years until about 19,000 years ago. As the glaciers formed and withdrew in alternating advances and retreats, they carved valleys and hills into the land. This process created the valley where the Village of Panama now sits, scraping against the hill where Panama Rocks are located, and exposing the rocks for the first time in millions of years.
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Once the rock formation was exposed at the end of the last ice age, weathering and slow movement called "geologic creep" widened the fractures and cracks in the rocks into the passageways the crevices guests can explore at Panama Rocks today.
As the Ice Age passed, a forest slowly grew over the site, but one that would look unfamiliar today. During this age, known as the Champlain Period, the local climate was warmer than it is now. Mastodons inhabited the area (portions of a mastodon were found just north of Jamestown in 1871), and the climate was suitable for cypress and semi-tropical vegetation. After the end of Champlain period a dense pine forest grew up in the area, which eventually gave way to the maple, beech, black ash and hemlock we see today. |
Blocks of Rock Move Downhill in "Geologic Creep"
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