Miller(Jacksonville) Esker Natural Area 23 thousand year old ridge and lake (Butler Co.PA) Geology
An Esker is formed by sub-glacial melt-water. Glacial melt-water carries large quantities of sand and gravel, as glaciers are known to scour and scrape rock and sediment and transport it as they creep across the land. Twenty-three thousand years ago there were glaciers in Northwestern Butler County. This area is located off of West Liberty Road, just East of interstate 79 and North of US 422, while South of Slippery Rock. The closest interstate exits would be I-79 Exit 99 (Portersville), or I-105 Slippery Rock. This video was filmed in the winter and it was neat to see ice on this lake that was formed by ice. The esker will appear as a sinuous ridge, approximately 40' (13 meters) high, and this section runs for approximately 2,000', which should be around 640 meters. The Esker is actually much longer, however parts of it have been mined, by local sand and gravel mining operations. The sand and gravel is used in construction materials, such as concrete and asphalt. This Esker is located near a terminal moraine, also called an end moraine, which is the limit of advance of a glacier. In this case, this would be the limit of the Southern advance of the Kent Glacier. The Park, just to the South is called Moraine State Park, because it straddles the line of maximum glacial advance. Areas that have been glaciated tend to be flatter and have more gently sloping hills, like much of the mid-western United States, while area that have not been glaciated tend to have landscapes that reflect shaping from water and mountain building. In Southwest Pennsylvania, there are many steep hills, however as you drive North on Interstate 79, around mile 100, the land becomes very flat, like most of Ohio. That is where the glaciers scraped away any hills that may have existed as a result of liquid water carving. Descending the opposite side of the esker (not visible from the road), one will notice a lake with an island. The lake feature is often called the eye of the esker. This is the best preserved (probably newest looking and large in size) esker in Pennsylvania. Other eskers exist. There is one in Mercer county that is far more advanced in age. As eskers age, (think of this esker in 10,000, 20,000 years, etc.) they tend to fill in along the edges through a process known as eutrophication. Decaying plant material falls into the lake, or blows in, and settles. Eventually the lake becomes shallower. The Lake will one day become a swamp, and then a bog. The video ends with me hiking back to my vehicle. If you make this hike, be careful there are lots of jagger bushes as we like to call them in Western Pennsylvania (watch out for thorns, briers, etc.). Also the access is limited to an area about 200' wide. On either side there are signs marked No Trespassing. Be careful to not wander off to far. A visit to this location took me about 20 minutes total. I would not plan an entire day around seeing the esker, but it is worth checking out if you are in the area and have not seen an esker before. This video is intended for hikers, and people interested in Geology, and if it is accurate perhaps it may be useful for those planning field trips or for instructional purposes. Finally, while I have a Bachelor of Science in Geology, and have done my best to fact check the information presented in this video, I do not hold a masters degree, a PHD, or a tenured position at any university. Where information provided in this video conflicts with information provided by someone with a MS degree, PHD, etc., defer to the smarter person. If you find something in the comments or have a suggestion that is reasonable to fix, I will do my best to correct it. Re-editing the video may take a while, but if it is full of errors, I will improve it. Mike Ciccone
Check out the following brochure from the Pennsylvania Geological Survey and the Pennsylvania Department of Conservation and Natural Resources for more information
Outstanding Geologic Feature of Pennsylvania: Jacksonville Esker, Butler County