Brief Geological History of Zoar Valley
Over 350 million years ago this area was covered by a vast inland sea. Sediment from mountains was washed down and settled at the bottom of the sea creating thick deposits. Eventually this sediment was pressed together and formed layers of sedimentary rock forming the bedrock for this region. The bedrock consists primarily of shale, siltstone, sandstone and conglomerates. Subsequent glacial advances and retreats carved their way through this bedrock and created a series of north-south channels throughout western New York. (The orientation of the Finger Lakes is one example of this).
As glaciers retreat they drop a mix of dirt, stones, gravel and other sediments. This accumulation is called a moraine, and the material making up the moraine is known as till. At the furthest advance the glacier can drop massive amounts of till forming a large moraine called a terminal moraine. A terminal moraine becomes something of a dam that blocks rivers and streams from passing. For example, streams such as the Allegheny River that used to flow north were blocked and now flow south. Most creeks and rivers follow these valleys in the bedrock.
Cattaraugus Creek, however, is very unusual. It does not flow north or south. It flows in a general east to west direction. What might cause this? Well, there is some debate about how this occurred. One common theory is that beginning around 65,000 years ago a series of glaciers covered the area, including the Wisconsin, Olean and Kent glaciations. These glaciers formed a moraine as they melted, blocking flow of water to the north. As the glaciers began their retreats they released massive amount of water along the leading edges that began to flow along the moraine. This seems reasonable since the bedrock has a slight natural dip in that direction. This huge flow of water cut through ridges in the bedrock exposing the shale and other sedimentary layers in those areas. Over many thousands of years the water eroded through the shale layers and formed the present valley. Some of the cliffs along the valley rise straight up to almost 400’ above the floor of the valley.
Earthcache Requirements
Note: DO NOT try to go over to the face of the waterfall, stay behind the guardrail.
Email or message the answers to the following questions. You may log your visit at anytime after sending your answers.
- Look at the face of the waterfall. How would you describe the surface of the face?
- Broken and jagged
- Somewhat smooth with a lot of evidence of cracked, broken off shale
- Quite smooth with very little evidence of broken off shale.
- Look at the thickness of the layers. In general would you say that the layers are thin and even or relatively thick and uneven?
- Is there any significant discoloration on this rock face? If there is, what do you think might be causing the discoloration. If there is not any just say that.
- Look at the face of the outcrop to the left of the parking area. Based on the questions above, compare this rock face to the rock behind the waterfall.
- Post a picture at or near one of the falls, but do not include any spoilers. The picture should include either you or a recognizable item such as a gps. This is your signature that you were there.
Description of Cache Site
There is enough parking for a couple of cars slightly to the southeast of these coordinates. Please watch for traffic in this area. It is not heavily traveled, but is located on a bend that can block your view somewhat.
At the coordinates given above there is a 70’ tall roadside cascading waterfall on Waterman Brook, a small tributary of Cattaraugus Creek which exposes a wall of shale. It is difficult to see the cascading nature of this falls, but if you cross the road and look above the sheer drop-off you can see a portion of the cascade on top. Next to the parking area there is another small exposed section of shale. You will be looking at both of these exposed areas to answers the questions below. (There is also one more small exposed section on the northwest side of the waterfall, but we won’t be needing that for this cache).
There is a tube that runs beneath the road to channel the water from the falls to the streambed on the other side. This portion of the tributary travels a small distance before it meets up with Cattaraugus Creek.
Shale
Rocks can be classified into three types: Igneous, Sedimentary, Metamorphic.
- Igneous rocks are formed when molten rock cools and solidifies. Pumice and basalt are examples of igneous rocks.
- Sedimentary rocks are formed as particles settle out of water (or possibly air) and accumulate in layers. Over long periods of time the weight of the upper layers eventually cements these particles into rock. Sandstone and shale are examples of a sedimentary rocks.
- Metamorphic rocks originated as either igneous or sedimentary rocks. Under the right conditions of heat, pressure and water the rocks undergo a change with new minerals forming and some of the original minerals getting carried away by water. Marble and slate are examples of metamorphic rocks.
Shale is a sedimentary rock that is formed when clay sediments are compressed and hardened. It is composed of at least 50% silt and clay sized particles. Quartz and feldspar typically make up much of the rock composition. Other minerals may be present which come from common minerals present in the local area. It generally forms in layers which can be fairly thick or extremely thin. It is very brittle, but soft. This combination means that it can be easily eroded.
References:
http://www.chbwv.com/Public_Meetings/Citizens_Task_Force/042716/Vaughan.pdf
https://en.wikipedia.org/wiki/Zoar_Valley
https://enchantedmountains.com/book/export/html/3313
https://www.dec.ny.gov/lands/36931.html
https://geology.com/rocks/shale.shtml