Geological Overview
The flat and relatively featureless landscape of the Black River Watershed deceives the more casual viewer into thinking that it lacks the geological drama of the Rockies or the Appalachians. In reality, the geological story of this area reveals dynamic change and evolution. About 360 million years ago, great seas covered Northeastern Ohio, leaving behind a sedimentary legacy revealed in the region’s upper bedrock layers. The evidence of these ancient seas is mostly concealed by recent glacial events that blanketed the area with a thick layer of glacial till. The rivers of Northeastern Ohio, on their slow northern route to Lake Erie, reveal these upper bedrock layers like the pages of a geological story. In Lorain County, the Black River bears the evidence of these ancient seas in the shale and sandstone formations along its northerly banks. An investigation of these formations will allow us to piece together the 360 million year history that shaped the landscape known today. The formation of bedrock materials, the layer of glacial till, the retreat of the glaciers, and the formation of the ancient Lake Plains and beach ridges all preceded the arrival of humans in the watershed. The first known inhabitants of the watershed followed the glacial retreats almost 10,000 years ago. Humans have become a geological influence on the watershed over the last 200 years of European settlement. Through the drainage of wetlands for industry, agriculture, and settlements, humans have altered the water courses and soil conditions throughout the watershed.

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Bedrock Formation
Extending south about ten miles from Lake Erie, cliffs of black Ohio Shale line the banks of the Black River’s mainstem. First visible just north of Elyria, this is the oldest exposed rock in the watershed, comprised of mud and clay particles that were deposited over 360 million years ago during the Late Devonian Period. Easily crumpled in your hand, the brittle shale formations contain clay and silt particles that have been compressed over time into the flakey shelves visible in places like the Black River Reservation. These particles originated from the ancestral Appalachian mountains to the East. Rivers and streams slowly eroded the mountains, depositing small particles in the shallow sea that covered Northern Ohio 360 million years ago. The clay and silt settled to the bottom of this sea, sorted by the action of waves. The Black River has exposed only one hundred feet of the Ohio Shale formation. A three hundred foot layer continues beneath Lake Erie.

The fossils of large pre-historic fish that inhabited the Devonian seas have been uncovered from the shale. In Sheffield, for example, the remains of a 20 foot long, armored fish were found by a local geologist, Jay Terrell. The species was named "terrelli” in 1873 when this arthrodire was first named Dinichthys terrelli, meaning "Terrell's terrible fish". Terrell also collected a specimen of the arthrodire Titanichthys clarkii along the lake shore in Sheffield. Preserved for over 360 million years by the shale, specimens of Dunkleosteus terrelli (as Dinichthys terrelli has been known since 1956) are on exhibit at the Cleveland Museum of Natural History. The massive head of the largest specimen, Cleveland Museum of Natural History 5768, spans more than three feet with a three inch thick skull and teeth five inches long. Besides Dunkleosteus, specimens of the arthrodires Titanichthys, Gorgonichthys clarki, and Heintzichthys gouldi, and fragmentary specimens of the sharks Cladoselache (teeth and cartilages) and Ctenacanthus (dorsal spine fragment), have also been found in the Cleveland Shale along the Black River by Lorain resident Peter A. Bungart and are in the Cleveland Museum of Natural History collection, as is Terrell's Titanichthys specimen.

Ten miles upstream from the mouth of the Black River, the Devonian rock ends and the Mississippian age rocks begin. These rocks are 320-345 million years old and comprise the youngest bedrock in the watershed. The Mississippian deposits were laid down in a more energetic ocean environment than the Devonian. These deposits have more sand, silt, bioturbation (movement of sediments by organisms), and wave ripples in their layers. The three Mississippian age rock formations found in the Black River Watershed are: the Bedford Shale, the Berea Sandstone, and the Cuyahoga Formation.

The Bedford Shale comprises the first layer above the Ohio Shale. The reddish color of the Bedford Shale contrasts with the dark gray hue of the Devonian shale. The Bedford is found downstream from Elyria before the sandstone waterfalls in Cascade Park. The shale layers are soft enough for small children to remove a chunk with their hands.

In Elyria’s Cascade Park the most well-known bedrock layer in the watershed, the Berea Sandstone, is visible for the first time. The Berea Sandstone is a Mississippian strata that has been used as a building material throughout the United States. The Berea Sandstone is a gray to buff colored stone which sparkles when the tiny sand grains reflect the sun. The Berea Sandstone formed 330 million years ago as a result of wave action from the great inland sea. The waves separated clay and silt from the larger sand grains, forming expansive beaches. In the sandstone escarpment of Cascade Park, evidence of the ancient sea’s wave ripples can be seen in the patterns of the stone. Compressed over time, the Berea Sandstone layer stretches along Northeastern Ohio, varying in thickness from 10 to 200 feet. The sandstone is durable, yet porous enough to be easily cut and shaped. Numerous sandstone quarries dot the landscape, remnants of the once thriving industry that designated Lorain County as the “sandstone capital” of the world.

The younger Cuyahoga Formation formed above the Berea layer, also as a result of the shallow inland sea. The Cuyahoga deposits range from a fossilferous clay to a light gray shale to a silty blue-gray sandstone. The headwaters of both the Main Branch and the West Branch of the Black River contain large outcrops of this formation.

After the Devonian and Mississipian formations, there is a 300 million year gap in the geological record of the watershed. Ohio’s shallow seas eventually disappeared as a result of the accumulation of sediment. The rising Appalachian Mountains to the east collided with landmasses in the middle of Ohio, forming a gentle arch across the entire state. Over time, the higher ground in Northeast Ohio eroded away along with the sediments that could reveal almost 300 million years of geological history. During this time gap, the dinosaurs appeared and then vanished, the continents separated from a single super-continent, and our early ancestors began to take their first steps as two-legged mammals.

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Glaciation
Over much of the past 2 million years, known as the Pleistocene Era, a thick sheet of ice covered 2/3 of Ohio. Known as the Ice Age, the Earth’s climate cooled considerably and a large percentage of the planet’s water accumulated as snow and ice in the polar regions. The ice sheets were over two miles deep in their center near Greenland and hundreds of feet thick at the edges. At the southern edge of this frozen expanse, the ebb and flow of glacial episodes significantly affected Ohio’s landscape.

The last great expansion of the ice sheet, the Wisconsian advance, left nearly all of the surface deposits in the watershed. The Wisconsian advances occurred between 70,000 and 25,000 years ago, following the Illinoian advance which happened over 125,000 years ago. Little glacial evidence exists from the Illinoian period due to the influence of Wisconsian era glaciers. The evidence of the Wisconsian advance can be found in the thick glacial till layer that blankets much of the Black River Watershed. Glacial till is a surface deposit about 50 feet thick consists of a mixture of loose sediments of clay, sand, and boulders. The glaciers accumulated till materials as they expanded southward. As the glacial waters melted, the till materials settled into the soils that we know today. Many of the rocks and boulders in the glacial till are Canadian in origin. Referred to as “glacial erratics”, these boulders traveled several hundred miles from Northern Canada during glacial advances. The glaciers also carved through the relatively soft sandstone and shale layers that comprise the upper layers of bedrock over Lake Erie, creating a deep basin for the eventual development of the lake. In the western part of Lake Erie, the limestone bedrock layers resisted the ice’s force and the glaciers carved a more shallow basin.

At the edges, advancing glaciers act like large bulldozers, pushing collections of till materials into large piles called “end moraine”. End moraine contains a wide mixture of clay and sand, as well as large rocks and boulders. The end moraine indicates the extent of the Wisconsian glaciers. In the southern portion of Lorain County, the Black River flows through several glacial end moraines. These deposits are continuous over large distances, with some moraine ridges in the headwaters over a mile wide. They contain rolling hills that are not eroded by surface water. These end moraines are named after the glacial events that created them. The Wabash, Fort Wayne, New Washington, Defiance and Spencer Moraines are all Wisconsian end moraines in the Black River Watershed. The Defiance and Spencer Moraines border the edge of the Watershed. Their hills in the Lodi area provide a major divide between the Great Lakes basin and the Ohio River Watershed. Just south of this end moraine, water eventually flows into the Ohio River.

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Lake Erie/Beach Ridges
The Ancient Beach Ridges that line the northern portion of the Black River Watershed formed as a result of periodic fluctuations of Lake Erie’s ancestral lakes. To understand the formation of these ridges, we will investigate the effects of geological change on the flow of water in the Erie basin. The force of gravity pulls water to the lowest elevation point through the path of least resistance. Today, the spectacular Niagara Falls define the lowest elevation of the Lake Erie basin where 258,000 cubic feet per second cascade into Lake Ontario. Niagara Falls is a recent geological development, however, preceded by wide fluctuations in Lake Erie’s drainage patterns.

Over the past 15,000 years, the elevation of ancestral lakes fluctuated as the waters of the Lake Eire basin tried to find the easiest path to the sea. The shifting lake elevation was the result of two natural events which occurred after the glaciers melted in Northeastern Ohio: isostatic rebound and the opening of outlets that were blocked by ice.

Isostatic rebound is the process by which land gradually rebounds after the weight of glaciers and other sediments has receded. The massive weight of the glaciers compressed the Northern part of Ohio, New England, and Canada beneath thousands of feet of ice. The land yielded to the pressure and slowly lowered into the earth’s mantle to reach equilibrium. Once the ice began to melt, the weight was lifted and the land began to slowly return to pre-glacial heights, a process that continues today. The previously glaciated areas rise at different rates because of variations in the weight and thickness of glacial ice sheets. As a result, some areas in the glaciated region rise faster than other areas, causing the lowest point of the drainage basin to shift over time. The northern coast of Lake Erie is rising more quickly than the southern coast. Like a bowl tipping southward, this action will slowly shift the lowest elevation point away from Niagara Falls.

The waxing and waning ice sheets in the north also affected the Lake Erie drainage basin. A large plug of ice sealed Niagara Falls about 10,000 years ago, causing the water in the Lake Erie basin to drain to the West toward Michigan. Over the next several thousand years, the ice sheets retreated, creating an opening that shifted the Erie drainage eastward into the Mohawk River. A cooling trend caused the ice to freeze and expand to block the outlet again. These trends caused wide fluctuations in the elevation of ancient lakes in the basin. These lakes exceeded the size of present-day Lake Erie. The remnants of these ancestral lakes can be detected in the sandy beach ridges that span the southern boundary of Lake Erie.

The beach ridges are a prominent feature on the Lake Plains of the Black River Watershed. Their height and sandy soils are unique to the region. The ridges formed when a lake level would stabilize and accumulate sediment along its shorelines. Waves along the shore carried the clay and silt sediment to the lake bed while the larger, more dense sand particles accumulated along the shores. Most of the ridges in the Black River Watershed travel east-to-west along the southern coast of Lake Erie. Early settlers took advantage of the good drainage and higher ground of the ridges, installing roads and establishing settlements along them. Butternut Ridge, Murray Ridge, Center Ridge and Middle Ridge Roads are examples of modern-day roads that were originally built on the ridges.

The most recent shift in the drainage of the Lake Erie basin coincided with the final retreat of the glaciers in the Niagara region. When the icy plug that sealed Niagara Falls finally melted away, the drainage of Lake Erie shifted from the west to the east. This caused a rapid drainage of the basin as the lake flooded the Niagara gorge with raging waters. The original falls were at an elevation 150 feet lower than today. Since this time Lake Erie has been slowly rising to its current shoreline of 573 ft above sea level. While it is unclear how long Lake Erie will stay at it’s current level, it will not remain static. Water will continue to erode the land while the area continues to rebound to pre-glacial heights.

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Soil Resources
The combination of the Lake Plains, Beach ridges, Till Plain, and Glaciated Plateau create a wide variety of different soil types. This geological variation in the watershed supports a diverse system of agricultural production. The rolling hills of the Glaciated Plateau and the more level Till Plains support livestock and cash grain production. Within these regions, silt loams make up 90% of the soils. These soils are comprised of medium to fine textured silt loams or silty-clay loams. Such soils are poorly drained and typical of nearly flat to gently rolling landscapes. Because of poor drainage and heavier clays, these soils are more suitable for corn, soybean, and livestock farming than fruit and vegetable production.

Soil erosion is a major problem along the Glaciated Low Plateau of western Medina and Southern Lorain Counties. Soil erosion occurs as a result of soil types, slope, and agricultural practices which leave the land bare for a portion of the year. After a rain storm, high volumes of water wash sediments off of exposed farm fields into the headwaters of the Black River. The steeper slopes increase the velocity of water running off the site. This higher velocity in combination with deep soil depths contribute to high rate of erosion. This erosion affects the long-term productivity of soil and is one of the leading causes of pollution in the Black River today.

To the north of the Glaciated Plateau, the Lake Plains support a wider variety of crops. The combination of ancient beach ridges and lake beds have made two distinct soils for farmers. Soils along the beach ridges are well-drained and sandy, making them ideal for orchard and vegetable crops. Production along the ridges is extended as sand grains retain the sun’s heat and the height of the ridges makes them the last to be touched by frost. However, water drains quickly from the sandy soils causing crops to dry out more quickly. The remnants of old swamps reside in the areas between the ridges. These swamps were drained by settlers in the late 1800’s. The clay and organic rich layers contain high levels of nutrients and, when drained effectively, are productive for vegetable crops. The majority of Lorain County’s older farms were concentrated along the beach ridges and surrounding wetlands. Rapid development in this part of the watershed has caused the retirement of many of these older farms.

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Water Resources
Groundwater is a product of the region’s geology. The impervious to slightly impervious layers of shale bedrock and sandstone offer little chance for surface water to percolate into groundwater aquifers. Although there are isolated exceptions, groundwater resources in the region are limited. According to Ohio EPA’s 1992 Water Quality Study of the Black River Watershed, groundwater yields an average of only 5-25 gallons per minute. One notable exception is the extreme southeastern zone of the Watershed near Lodi where groundwater from a buried valley aquifer yields 100-500 gallons per minute. Groundwater in the clay and silt deposits near the mouth of the Black River is extremely scarce, yielding less then 5 gallons per minute.

The flow of the Black River is not dependent upon groundwater. This is particularly true of the mainstem where impervious shale bedrock restricts any significant contribution of groundwater. With an average rainfall of 35 inches per year, the Black River derives its flow from storm runoff. The dependence of the Black River upon precipitation causes the river to experience wide fluctuations in stream flow throughout the year. These fluctuations have become more extreme in recent years as a result of urban development which increases impervious surface and the volume of water surging into the Black River.

Dependence on groundwater for public water supplies in the watershed is minimal. Less then 5% of the households in the region rely on wells for drinking water. The majority of these households are in the town of Lodi, where three wells pump around 400,000 gallons a day to the town’s residents and businesses. (1997 figures) The bulk of public water is provided by a network of above ground reservoirs and intake from Lake Erie. Oberlin and Wellington are the only towns left that withdraw their public water supply directly from the Black River to recharge their reservoirs. The rest of the towns get most of their water pumped in from Lake Erie. The Rural Lorain County Water Authority (RLCWA) supplies water to the un-incorporated areas of Lorain, North Ashland and West Medina Counties. These towns include Grafton, LaGrange, Spencer, Pittsfield, Penfield, Litchfield , Chatham and others. The RLCWA pumps in over 3 billion gallons yearly through underground pipes that draw water from Lake Erie (at Avon Lake) and the Vermilion River at the New London Reservoir. Hence, most of the municipalities of the Black River watershed receive drinking water from sources outside of the immediate watershed.

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This project was financed in part through a grant from the Ohio Environmental Protection Agency and the United States Environmental Protection Agency, under the provisions of Section 319(h) of the Clean Water Act.  These grant monies were matched in part or totally through funding by The Northeast Ohio Areawide Coordinating Agency (NOACA) and in-kind contributions from local agencies.