Re-Examining the Devonian and Early Mississippian Shales in Northeast Ohio

Brizendine 1

Jamison Brizendine

Meg Streepey

Senior Seminar

17 October 2005

Re-Examining the Devonian and Early Mississippian Shales in Northeast Ohio

Abstract:

The Devonian Shales in Northeast Ohio are invaluable to many geologists. The Cleveland Shale in particular is interesting because it contains oil, trace amounts of Uranium and natural gas. The oldest Chagrin Shale Formation is of interest because many geologists are unsure if it is a pinch-out member. In Kentucky the Chagrin is a very thin layer. The overlying Bedford Shale contains a unique blue sandstone member called the Euclid Member. The Chagrin Shale, the Cleveland Shale, and the Bedford Shale all have varying degrees of thicknesses. A few papers have measured the various thicknesses of these beds, but measurements are outdated and need to be reviewed. The aim of this research is to enlarge and combine much of the old research of the Devonian shales of Northeast Ohio.

Introduction:

The Devonian Shales of Northeast Ohio are predominantly the Ohio Shale members of Ohio and New Albany Shale Formations of Kentucky, Indiana and Illinois. The Chagrin Shale, the oldest member that is exposed in Northeast Ohio is a blue-gray to greenish-gray shale that weathers to a soft clay. This formation has exposed several disconformities, and fossils are found within the upper layers in this shale. The fossils are fragile because the shale can be easily broken up. One of the mysteries that should be researched is the nature of the Chagrin Shale Formation, because it is found throughout Ohio, and follows the Cincinnati Arch (Ettersohn F.R., Barron L.S. 1981), but it pinches out towards Kentucky and West Virginia.

The formation above the Chagrin is the Cleveland Shale. This shale is a black, fissile shale that is fairly resistant. It weathers to a brown and reddish black, but it is jet black when freshly exposed. Right above that contact a blue-gray sandstone member exists called the Olmstead Member (Lamborn 1939). This has been confused in the past with the Euclid Bluestone member, found in the Bedford Shale Formation. Fossils have been found in the Cleveland Shale formation, but like the underlying Chagrin Shale, the fossils are fragile (Frank 1960). Bits of scales, fish jaws and remains of small sharks have been found in this formation.

The youngest shale formation that the research will examine is the Bedford Shale Formation. The Bedford Shale is not continuous throughout the entire formation, which can lead to further study. The basal part of this formation is a thin layer of blue-gray shale grades into the Euclid Sandstone Member. This member, which has been referred to as the Euclid Bluestone member, is about fifteen to twenty feet, and another twenty feet of the blue-gray Bedford Shale lies above it. The final part of this formation is a layer of chocolate-reddish argillaceous shale, which then grades into the Berea Sandstone member. The contact between the Berea Sandstone and the Bedford Shale forms a disconformity (Lamborn 1939). This formation is unique because the United States Geological Survey has placed this formation between the Devonian and Mississippian periods.

The surveys of these formations have laid the foundations of the Northeast Ohio Stratigraphic column. These shales are important for the economic value that they contain, however they need a more complete synthesis for hydrogeologists, paleontologists, geochemists and stratigraphers to be of any use.

Synthesis:

What we know about the Devonian Shales in Northeast Ohio is enough for many geologists. However there is still much to be discovered and researched. Each formation will be examined from the oldest to youngest that is exposed in northeast Ohio. Even though the Huron Member of the Ohio Shale is exposed in central Ohio, it is not visible in Northeast Ohio. Even though some geologists have placed the Bedford Shale Formation in the Mississippian (Alkire 1950, Criley 1970, Heimlich 1974) it is still included in this paper.

The Chagrin Shale is described as a greenish-gray or a blue-gray shale and is named from the ChagrinRiver that runs throughout Geauga and CuyahogaCounties in Ohio. The Chagrin tends to erode into a soft clay and produces steep banks after eroding. Ettersohn and Barron (1981) have labeled the Chagrin as the Three-Lick Bed, because it is much smaller in Kentucky than it is in Ohio. The Chagrin unlike the older Huron Member or the Cleveland Shale, has little or no organic matter, which it makes it inappropriate as a oil producing unit (Alkire 1950). Additionally the Chagrin Shale is sandier than the overlying Cleveland Shale and the underlying Huron Shale. The Collinwood Brick & Supply Company and the Buckeye Shale Brick Company to make paving bricks in construction work have used the Chagrin Shale. The Cleveland Brick and Clay Company use the Chagrin Shale to make about forty-five thousand bricks a day.

Measuring the Chagrin Shale can be a little tricky because it lies on sea level and most of the unit is invisible in Northeast Ohio. The Chagrin Shale is exposed throughout Ohio and Kentucky, and measures about 500 feet total, but about 175 feet above lake level in Northeast Ohio. In Tinker’s Creek the Chagrin is exposed only about fifteen feet. In DelawareCounty, near Columbus, the Chagrin becomes part of the Ohio Shale, which the total formation is about 650 feet. In Kentucky the Chagrin is about 70 feet, between the Cleveland and the Huron Shale (Ettersohn and Barron 1981). Either there was little deposition in that area of the Chagrin or the Chagrin may be a pinch out, because it does not exist in the central, western, southwestern and northwestern portions of Ohio.

The Chagrin is fairly devoid of fossils except for the uppermost layers. The fossils in the Chagrin match those of the Chemung Formation in Pennslyvania and New York, confirming its time period is in the Upper Devonian. Spirifer disjunctus, Arthyris polita, Chonetes setiger, Dalmanella tioga, Lingula sp., Orbiculoidea newberryi, and Productella hirsute, have been successfully found in the Chagrin Shale (Thompson 1951). Downs Schaff made the last complete analysis of the Chagrin Shale for the Graham Clay

Products Company in 1929 (Lamborn 1938).

The contact between the Cleveland Shale and the Chagrin shale is about 1 to 3 centimeters of pyrite. In some places the contact has been a disconformity, while in places like EuclidPark, the contact is conformable. The Cleveland also contains a ten to fifteen meter sandstone member called the Olmstead Member. This member has been confused with the Euclid Bluestone Member in the Bedford Formation (Gray 1951).

The Cleveland Shale Formation, along with the Chagrin Shale is part of the Ohio Shale Formation. Going south towards Columbus, the Cleveland becomes the Ohio Shale, because of the disappearance of the Chagrin Shale, while in Kentucky the Cleveland still exists with the Three-Lick Bed underneath it.

The Cleveland Shale is described as a resistant and dark shale. When it is freshly broken it is brown, but weathers to a reddish-brown color, and may contain marcasite and pyrite. Hoover (et. 1960) reports that the shale contains quartz, pyrite, illite and chlorite, and it also appears there is no carbonate at all in the Cleveland. The Cleveland Shale is lithologically similar to the Huron Shale, and the Ohio Shale in Columbus, and the New Albany Shale in Indiana and Illinois.

Economically the Cleveland Shale has been used for ceramic products, but as a raw product its usefulness ends there. The Cleveland is more useful as a bedrock, and an oil producing member in the Ohio Shale. The natural gas is trapped in the local joint planes in the Cleveland. In the 1950’s it was used to produce kerosene and then in the 1960’s and 1970’s it was used to produce oil and natural gas. In northeastern Ohio, the Cleveland Formation oil wells are only about 300 to about 600 feet deep with about 40 to 60 pounds in pressure (Alkire 1951). The Cleveland is more productive in southeastern Ohio, because the sandstone lenses provide a reservoir rock. The Cleveland Shale also contains about 0.003 percent, about 30 to 40 parts per million, of Uranium, The Atomic Energy commission requires, however, that the uranium concentration has to be higher than 0.1 percent to be of any commericial value (Hoover 1960). However the small amounts of uranium decay to lead. This becomes a problem, because radon becomes trapped in basements as a by-product of this decay.

In terms of thicknesses, it is a lot easier to judge the thickness of the Cleveland, because it is exposed more frequently than the Chagrin and has more exposed outcrops. In northeast Ohio the Cleveland is about 20 to 50 feet in length (Hoover 1960). However it increases in thickness toward ErieCounty at 60 feet. The maximum known thickness of the Cleveland Formation is 90-100 feet, but that location is not revealed to us by Manning (1953). At the border of Pennsylvania and Ohio, the Cleveland Shale pinches out. In other locations the thickness is not known.

The Cleveland Formation is generally devoid of any fossils. About twenty fossils have been identified throughout the formation. However most of the fossils that receive the most attention are the fish like Dinichythys and Dunkleosaurus. Downs Schaff made the last complete analysis of the Cleveland Shale for the Graham Clay Products Company in 1929 (Lamborn 1938).

The Bedford Shale is reported by most authors to be of Mississippian Age (Alkire 1950, Criley 1970, Heimlich 1974). It lies conformably above the Cleveland Shale and there is an easy transition from one rock type to the other. The Bedford is part of the Waverly group and can be subdivided by two divisions: A lower blue shale, and an upper red shale-siltstone. The middle of these two layers is a small pinch-out called the Euclid Sandstone. The Bedford Shale Formation has an unconformable contact with the Berea Sandstone Formation. Toward southern Ohio and southwestern Ohio, the two formations can no longer be separated from each other. In Tinkers Creek, however the upper portion of the Bedford is a blue-gray shale with sandstone layers (Frank 1961). This upper layer has been called the Sagamore lentil. The Euclid Sandstone member is about 15-20 feet total within the lower portion of the Bedford. This member has been used in the past for making flagstones that pave the sidewalks of the Cleveland area. The Bedford Formation as a whole does not have any economical use.

The deposition could be speculated that gray mud and silt was introduced into the system and then was deposited directly on top of the Cleveland Shale. The Bedford Formation is the only Devonian/Mississippian Formation that contains oscillating ripple marks that are about 3 to 5 inches apart. The upper portion of the Bedford in Northeast Ohio is predominantly a red clayey shale-siltstone (Frank 1961). The mineralogy of the Bedford is quartz, illite, chlorite, and kaolinite. The clay member that dominates the Bedford is illite (Hoover 1960). In the bottom portions of the Bedford, pyrite and marcasite nodules have been found in the shales.

True thickness cannot be obtained for the Bedford Formation because of the unconformable contact with the Berea Sandstone and the uncertainty of the contacts with the Cleveland Formation. To make matters worse, the thickness of the Bedford Shale varies in so many places that is difficult to make a definite measurement. At Tinkers Creek in CuyahogaCounty, the thickness is about 85 feet thick. Going Easterly form their the thickness goes from 85 feet to about 44 feet, but in Erie County the thickness of the Bedford is about 150 feet. FranklinCounty reports the thickness to be about 95 feet. However in Kentucky the thickness of the Bedford drops to a few inches. One of the problems is that many authors have placed this formation in the Mississippian, while some (Hannibal 2001) have placed the Bedford in the Devonian.

The fossil zone of the Bedford varies from location to location. At Tinkers Creek it is rather fossiliferous, but in Summit county it is not. The fossil diversity is rather low with about only four major fossils found within the Bedford Formation. Downs Schaff made the last complete analysis of the Bedford Shale for the Graham Clay Products Company in 1929 (Lamborn 1938).

Future Directions:

The literature for Devonian and Mississippian Shales still poses many problems that can be addressed through more field work. All three shales could use a more complete geochemical analysis of their properties. The last known publication of the economic aspects of the shales was made in 1960. What is the total thickness of the Chagrin Shale? Is the Chagrin Shale a unique depositional environment that is a local formation or is it a pinchout that continues until it disappears?

Is the Cleveland Shale still being drilled for gas? If so how much does it produce on average in Ohio? Many papers have covered this formation such as the thermal maturation levels for gas, but it is only available for areas in Kentucky. What is the thermal maturation for oil and gas for the Cleveland Shale in Ohio?

The Bedford Shale makes a unique formation throughout the stratigraphical history of Ohio. In many cases several units and members crop in and out. Should these units be recognized, like the Sagamore lentil, or should it be ignored? The Bedford has always had two main shale units, should these have their own unique names, or should they be ignored? Since the thickness of the Bedford varies so much, what is it’s depositional history when compared to the Berea Sandstone? Is the Bedford Formation like the Chagrin and becomes a pinch-out throughout Ohio? Can the Bedford Formation be used in making bricks like the Chagrin? Is the Bedford Formation in the Devonian or in the Mississippian Period?

Many questions need to be addressed in order to have a more complete history of the stratigraphy of Northeast Ohio. For measuring thicknesses, non-destructive methods like Geophysical Resistance Werhner Pole arrays can measure small-scale changes. Another method is using a laser total station for more accurate thickness measurements. A slightly more expensive option to measure thicknesses would be drilling test cores. A simple geochemical analysis of these shales would be useful as well. Finding up to date mapping would be helpful in measuring thicknesses in various parts of the state. These answers will be helpful to paleontologists, geochemists and sedimentologists.

Summary:

The Devonian and Mississippian shales provide much research material because the formations are economically important to northeast Ohio. With a complete analysis many geologists and geochemists can study the paleoclimate of northeast Ohio. As stated above there are several opportunities to update the existing information for these formations. Each formation is unique in studying the environment of the area, but many questions can still be answered, with more field work.