Panther Mountain Meteorite Crater
(Courtesy NASA/LPI) The Catskill Mountains have evolved with the erosion of kilometres thick sedimentary rock over a period of 375 million years. This landsat image of the Catskills reveals the randomness of this mountain forming erosion. The circular anomaly indicated in the center of the superimposed square is postulated to be the result of an impact event. For reference, the Hudson River is on the right.
In the Devonian Quaternary, the probable time of impact, this landscape was a gentle sloaping plain with the Acadian Mountains to the east and the saltwater Kaskaskia Sea to the west. The life forms on earth at that time included early land plants, amphibians and ammonites. Over the next 375 million years;
(Courtesy NASA) A magnified view of the round anomaly illustrates the circular valley formed by the Esopus Creek and suggests a “crater like” structure. It was from these images that Y.W. Isachsen began his study of this structure to seek evidence of an impact event.
We approached the crater from the north along its eastern rim. This plot shows the random pattern we flew over the crater to get our images. We were limited to 3000’ above ground because of cloud cover and at this low altitude the crater feature was not easy to identify. I understood how large the feature was before I started on this trip, but when I first saw the crater, its immensity astonished me! I used the GPS to confirm that I was actually looking at the crater.
Looking northwest from the eastern rim, the circular shape of the feature is obvious. In these images note the road and valley veering off to the left background. This is the eroded valley directly over the crater rim. The distance from the valley floor to the peak of Panther Mountain is approximately 800 meters. Seismographic studies inferred that there are concentrated joints in all parts over the crater rim. The joints make it relatively easier for streams to erode the rocks over the crater rim and form the circular shape.
At the northern part of the crater looking south, the southern rim is visible circling behind the Panther Mountain peak. A negative gravity anomaly centered at this peak gives evidence that there is a zone of shattered rock deep beneath the mountain. Specifically, the Earth’s gravity is slightly weaker above the mountain than was expected (confirmed by gravitometer). This suggests that the rock beneath the mountain has been disturbed, making it less dense. The zone of disturbed rock, in turn, could account for the larger number of joints found along the edge of the circle. As the fractured rock material settled, the overlying sedimentary rocks sagged, and the joints formed around the edge of the circle to relieve the stress.
In these three images are viewed as we circled the crater from along its south rim from the west to east. The amount of sedimentary rock deposition and then the erosion that has occurred over the past 375 million years is displayed. The crater itself is over 800 meters below the peak of Panther Mountain. This is the area of the upper part of the Esopus Creek where closely-spaced joints in the bedrock near the stream were documented. In the lower reaches of the stream (to the north), the bedrock is buried beneath glacial deposits.
Ground Exploration of the Panther Mountain Structure
Following my crater exploration tradition, I just had to physically stand on the structure that was formed over the Panther Mountain crater. I wanted to do this even though the “crater” of Panther Mountain is under approximately a kilometre (~3300 feet) of sedimentary rock and is not physically accessible.
It is a relatively easy but long climb and hike from the south parameter parking lot to the summit. Panther Mountain at approximately 1,135 metres (3,720 feet) in elevation is the 18th highest in this uplifted Catskills region.
This image, taken at approximately 3500 feet elevation, documents the various types of sedimentary deposits in the area. Hundreds of millions of years ago the eroded remnants of the Acadian Mountains to the east were deposited here to form Panther Mountain and the Catskills. The sediments traveled westward and formed a delta into the sea that covered the area at that time. This delta was then uplifted and eroded. These 2 cm (~1 inch) pebbles inserted in the sediment are small rock deposits from a river outlet, and over these pebbles is a smooth layer of fine sediment that was deposited through deeper waters. This outcrop illustrates the various stages of deposition and erosion over the eons and is typical of the geology of the structure. The floor of the crater is over 1 kilometre (3300 feet) directly below here.
I took this image at the top of the structure looking to the north-east. Starting from the left of the image and panning to the right you will notice the “blue” colour of the distant hills compared to the true colour of the foreground hills. Hidden behind the foreground hills is a valley made from the creeks eroding through the rocks that cover the circular crater rim. The actual crater rim is buried under several hundreds of metres of rock. Looking toward the crater rim from here gave me an appreciation of the size of this impact structure as the distance to that hidden valley is the radius of the structure.
This image was taken looking to the east. The buried crater rim is located in the distance under the valley indicated by the white (X). Again, to view the absolute size of the structure is something to experience.
In summary, approximately 375 million years ago a bolide probably impacted here in a shallow sea creating a 10 km (6.21 mile) diameter crater. This crater eventually filled with sediments and through the process of uplift and erosion became Panther Mountain. The mountain took the shape of a longitudinal ridge in the center of the rough circle eroded by Esopus and Woodland creeks. The resulting “inverted relief” structure (described below) is BIG, and I am looking forward to researching any future geological investigations here.
Panther Mountain Crater “Analog” on Mars
An “analog” of the Panther Mountain meteorite crater was recently documented on the surface of MARS by the MARS EXPRESS of the European Space Agency.
This image, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft, shows part of a heavily eroded impact crater at Solis Planum, in the Thaumasia region of Mars.
The northern end of the higher region (upper left in this image) contains an almost circular plateau, which is 15 kilometres across.
This circular plateau may be an old impact crater which was filled by sediments. Over time these sediments in the crater developed a harder consistency than the surrounding material. Later, the more easily eroded surrounding material was removed by erosion and the harder inner filling remained forming the circular plateau. This phenomenon is called ‘Inverted Relief’.