Toledo Area Fault Line

I was unaware that a 100-mile long fault line existed in the Toledo area, and that it could be visible when the Maumee River is low.

Feb 9, 2017 - Toledo Blade - Protesters: Fault line an issue for plan - Group calls for company to reroute its pipeline

Excerpts:

To thousands of people who hike inside Farnsworth Metropark each year, the Bowling Green Fault is no secret: There’s even a marker along a paved trail showing where a portion of it exists near Waterville.

The marker, by Metroparks of the Toledo Area, states that the 100-mile fault — which goes from Findlay to southeast Michigan — is so close to the surface it can be visible to the human eye in that part of northwest Ohio when the Maumee River’s running low.

Spectra, developing the project with DTE Energy and others, has said in documents it provided to the Federal Energy Regulatory Commission that it believes the fault is 2,200 feet or more below Earth’s surface — nearly a half-mile. That information was used in the project’s final environmental impact statement, which asserts the proposed route does not include earthquake-prone areas.

But Andrew Kear, a Bowling Green State University assistant professor who specializes in geology and environmental policy issues, said at a rally Wednesday the Waterville area is one of the “worst possible” places for such a pipeline because of its seismic potential and porous karst geology.

“When water is low, you can walk along the Maumee River next to the crack,” Mr. Lodge said.

Bowling Green Fault System

A little web searching showed that this Toledo area fault line is named the Bowling Green Fault System.

Map of Ohio's fault lines.

map of ohio's fault lines


PDF report from geosurvey.ohiodnr.gov titled Structure Contour Map on the Precambrian Unconformity Surface in Ohio and Related Basement Features

From the geosurvey.ohiodnr.gov website about the report and the above image:

This map portrays a number of deep faults and other structures that have been identified by a variety of geologic studies. Some faults are well known, whereas others are speculative. Very few of them are visible at the surface. The Anna, or Fort Wayne, rift in western Ohio is the site of numerous historic earthquakes.


geosurvey.ohiodnr.gov :


Excerpts from a 2007 post at geocaching.com titled The Bowling Green Fault

The Bowling Green Fault is the most significant geological feature of northwest Ohio. The fault is one of the largest in Ohio which runs from Michigan to south of Findley. The deepest part of the fault is just to the southwest of Bowling Green which is about 200 feet deep. Your view of the fault here at Metroparks Toledo is one of the very few places that the Bowling Green Fault can be seen. The only other place’s that the main fault can be seen on occasion is in a few of the quarries in the Maumee area.

A fault is a fracture or zone of fractures (cracks) in the rock that makes up the earths crust. Faults allow the rock to shift apart from each other. The shifts can be horizontal or vertical, we will be looking at these movements later in this cache.

The Bowling Green Fault dates back some 100 million year since its last movement. It is estimated to have been an earthquake with a 5 magnitude to have caused this movement in the earth’s surface that we are looking at here. This entire area show signs of the earthquake that took place here. This cache will take you to, and show some of the effects of this fault. The Bowling Green area still produces earthquakes but none to the magnitude that causes the crust to move.

This cache will take you on a lesson in different compressions of the earths crust caused by the fault. The rock here dates back to the Paleozoic period which is from 248 to 543 million years ago. Along with the Bowling Green Fault we will be looking at a secondary fault and a compression of the earths crust.

Parking is available in two areas near the posted co-ordinance. Pay close attention to which parking you chose here. If you chose to park to the east you will have a shorter distance but you will be facing a terrain of about a 3.5 to 4.0. Chose the parking to the west (N41 29.240 W083 44.047) the walk will be longer with only a 1.5 terrain. Depending on your choice of routes will determine the order of the following tasks.

  1. At the posted co-ords you will find a sign that tells you about the Bowling Green Fault.

  2. Go to N41 29.242 W083 43.989. Here you will get a clear view of a fault caused by the Bowling Green Fault.

  3. Go to N41 29.242 W083 43.972. Here you will see a compression in the layers of rock, in its much larger version it would be called “orogenic activity”. Describe in detail the shape of the compression of the layers here.

  4. Go to N41 29.259 W083 43.867. You will now in the Bowling Green Fault. Here you will need to take a photo of yourself or team with the rock that has been spilt by the fault. Post this photo along with your log.