When the earth took spherical and solid form, it presented in the earliest ages whose records have been deciphered on the rocks, a surface of land and water. The continental areas were then limited and low. Much of what now constitutes the dry land was under water. In North America the land portions were chiefly north of the Great Lakes. What is now the Mississippi valley was then covered by a great inland sea of comparatively shallow depth.

It should be remembered, even at the expense of repetition, that sedimentary rocks, or those formed and placed by the action of water, are deposited in successive layers or strata. At the basis of all such rock formation is what, for a better designation, we may call the primordial bed rock. Scientists differ as to its origin. Those who still accept the nebular hypothesis of Laplace claim that this bed rock is a part of the original crust of the earth and was formed when the surface changed, in cooling, from a molton to a solid condition. Others claim that the heat that produced this came from the center of the earth. It is enough for us to know that this primordial bed rock exists; that its condition is due to heat; that the elements composing it are of igneous or metamorphic origin. Upon this foundation were deposited the sedimentary rock formations of subsequent time.

The bed rock in some regions attained great thickness - 12,000 feet in the canyon of the Colorado; one to nine miles in portions of Canada. It furnishes granite building stones and the rich copper and iron deposits of the Lake Superior region. In Ohio, however, it is known only as the bed rock upon which the sedimentary rocks of succeeding ages have been laid.

In the periods of the formation of this bed-rock, life is supposed to have first appeared. Its earliest forms left no fossil remains, but were carried over into the more numerous and substantial life forms of the Cambrian period.

The action of the water washed sediment from the land which was deposited over the ocean bed. Through the Cambrian period of rock formation what is now Ohio was under water. Through most of the Ordovician period which followed it was still a portion of the bed of the great interior salt water sea, but near the close of that period a small portion, about one-eighteenth of the entire state, emerged from the water. It was part of an island that lay in the states of Indiana, Kentucky and Ohio. A glance at the map will show the extent of the island at this period.

In the Cambrian era many forms of animal life appeared in the shallow interior ocean. These were trilobites, brachiopods, sea worms and mollusks, pelecypods (oysters).

Most of these forms of life were carried over to the succeeding Ordovician period. Their remains abound in the surface rocks that appear in the first dry land of Ohio. Vegetation, if it existed at all, was confined to the simplest and lowest forms of plant life.

The portion of Ohio that had risen from the sea at the close of the Ordovician period included all of Hamilton, Clermont, Brown, Butler, Warren and portions of Adams, Highland, Clinton, Greene, Montgomery, Preble, Clarke and Miami counties.

The primordial bed rock of the great inland sea, at the close of the Ordovician period, was overlaid with two series of rock formations – the Cambrian and the Ordovician - deposited through millions of years by action of the water.

The Ordovician period was succeeded by the Silurian. Some of the older text books of geology call the Ordovician period the Lower Silurian and the period that we are now about to consider the Upper Silurian. The modern nomenclature is here followed.

In the Silurian period the forms of life of Ordovician time continued and some new form appeared. The marine life was much more abundant than in the previous period. Blastoids appeared for the first time. Star fishes and serpent stars were not very numerous. Trilobites were abundant as were brachiopods, mollusks and corals. At the close of the period the earliest scorpions left their remains in some of the rock formations. Fish also began to appear and signalize the transition to the next period in the progress of animal life.

Geologists generally agree that vegetation occurred on the land through this period, limited to very narrow portions along the shore line, but practically no evidence of this fact is found in the rock fossils.

Through this period there was a gradual emergence of Ohio from the interior sea which continued to be salt water. It is assumed that the water of this interior sea at this time evaporated more rapidly than if flowed in from the ocean. The great salt formations were then formed farther to the East, especially in the State of New York. The saline formations of Ohio are supposed to have had a similar origin.

The emergence of the land from the waters of the sea was not continuous and uninterrupted. At times there were subsidences of the land but on the whole there was a distinct extension of the portion above the water. At the close of what is generally included in the Silurian period the following counties had emerged: Hamilton, Clearmont, Brown, Butler, Warren, Clinton, Preble, Montgomery, Greene, Darke, Miami and Shelby together with portions of the following counties: Adams, Highland, Fayette, Clarke, Campaign, Logan, Auglaise, Mercer, VanWert, Allen, Hardin, Marion, Wyandotte, Hancock, Seneca, Wood, Sandusky, Ottowa and Lucas.

If the period of the Monroe limestone formation is added as a part of the Silurian there is a considerable extension of dry land as seen by reference to the map. At the close of that period the western shore line passed through Paulding, Putnam, Henry, Wood and Lucas counties; while the eastern shore, which was clearly defined, extended southward from the northwest corner of Erie County through Sandusky, Seneca, Wyandotte, Marion, Delaware, Union, Madison, Franklin, Pickaway, Ross, Fayette, Pike and Adams counties.

It will be seen that the dry land of Ohio in process of formation now extended from the lakes to a line afterward followed by the Ohio River.

Next in order of time came the Devonian period, sometimes spoken of as the age of fishes, because of their appearance in great numbers for the first time in this period.

The forms of marine life of the previous period continued, most of them abundantly. This could not be said of some forms, however. The trilobites, the fossils of which so frequently abound in Ordovician and Silurian time, are now less frequently found in the rock formations of this period. The Devonian limestone measures of Ohio are rich in fossil remains. The state house is built of this limestone. In the survey of the Columbus quadrangle under the direction of State Geologist J.A. Bowndocker, a very complete description of the Devonian limestone of this vicinity and its fossil remains is presented in a most interesting bulletin. Among the fossils described are the following classes: Brachiopods, crustallans, pelecypods, gastropods, cephalopods and others of minor importance. It is interesting to note that among the crustations are found some excellent specimen fossils of the trilobite, in spite of the fact that at this period the tide was turning against this interesting representative of paleozic time. The pleuronotus decewi, a coiled gastropod, whose fossil remains are common in the Columbus limestone, is well illustrated in the cut from the bulletin to which reference has been made. Other forms of life belonging to this period are liberally illustrated in the same work and a few of the cuts are presented here.

But this, as observed at the beginning, was not inappropriately styled the age of fishes. The fossils of these are well represented in the rock formations of Ohio. Doctor Chamberlain in one of his recent books thus describes characteristic life of this period:

"Fishes were a conspicuous part of the new fauna. The arthrodirans reached their climax, and some of the species were among the largest fish ever known. Some of them had an estimated length of twenty feet, and had strong mandibles two feet long which, in lieu of teeth, had cutting edges that closed shears-like, after the fashion of the mandibles of turtles. The front part of the body was encased in heavy plates. Some of the fin-spines of sharks were a foot long."

The author of the above statement then presents as illustration of the fossil remains of a portion of one of these fish found in the Devonian rocks near Delaware, Ohio.

At this time the interior sea, which still covered more than the eastern half of what is now Ohio, was teeming with sharks which seemed to have been masters of the briny deep. Their remains are found in different portions of the rock formation of the Devonian period. Some of the finest specimens have been found in the northern part of the state.

Considerable progress had been made in the land life through this period, which, at its close was represented by plants, snails, insects, myriapods, scorpions and amphibians. The plants had little foliage. They included ferns, rushes, and other simple forms. Near the close of the period plant life had made considerable progress. Forests began to appear in marshy places on the sea shore and along the streams. These were made up of fern-like and rush-like growths of large size. And club mosses are said to have attained the height of small trees.

The progress of emergence from the sea in the Ohio region continued through this period. At its close all the western part of the state, except small portions of Fulton and Defiance counties and most of Williams County, was dry land. The southern shore of Lake Erie had developed though it was separated in places by a very narrow strip of land from the interior sea that still spread over the eastern portion of the state. Most of Astabula County, as will be seen from the map, was dry land. Thence the shore line extended through Lake, Cuyahoga, Lorin, Erie, Huron, Crawford, Morrow, Delaware, Franklin, Pickaway, Ross, Pike and Adams counties.

At the close of the Devonian period the rock formations of the epicontinental sea consisted successively of the Cambrian, Ordovician, Silurian and Devonian periods. These were built up regularly from the primordial bedrock and all were covered by the sea, which has gradually been growing more shallow and marsh-like. Soon the dense vegetation of the Carboniferous period appeared in all its grandure. It is believed that the marshes were overhung with a dense fog, through which the sun-rays penetrated but dimly. Huge ferns were in evidence almost everywhere, and dense thickets of Calamites rose from the sodden earth to a height of forty feet. These plants were closely allied to the equiseta or "horse-tails" of the present. The east monotonous forests were made up of a number of trees, chief of which were the Lepidodendrons and the Sigillaria. The Lepidodendron was a club-moss that frequently grew to the height of seventy feet, branching somewhat after the manner of modern trees. The leaf-scars of the body were systematically arranged in spiral lines, due to the arrangement of the spine-like leaves before they fell. The Sigillaria was similar to the Lepidodendron, but its trunk was vertically fluted, and in these flutes the leaf scars were like the impressions of a seal. It seems to have been less disposed, than the Lepidodendron, to divide into branches.

The plants of this period reached through many degrees of latitude. It seems that there must have been a somewhat equable temperature from the equator almost to the north pole.

In the Ohio region this vegetation was especially dense. Year after year it grew upward and fell into the swampy remnant of the epicontinental sea until vast stores of it were collected beneath the stagnant waters. As this sea bed gradually sank the vegetable growth accumulated in enormous masses over wide areas. Later the bed of the sea seemed to sink more rapidly than the vegetable growth accumulated, and finally great masses of gravel and sand and silt washed in and covered up the vegetation beds. Above them limestone and sandstone formations spread over large areas, and shales were at certain periods deposited. Finally the bed of the sea began to rise again, and these various formations were once more brought above the surface. Through the thousands of years that these changes were in progress the vegetable accumulations were compressed into veins of coal.

There can be no question as to the origin of the coal measures. Throughout Ohio the coal veins are closely associated with impressions of ferns and trees and practically everything that went to make up the vegetable growth of the period. Stumps of trees have been preserved in form, though converted into stone, that are so natural that even a child could distinguish them at once as tree stumps. Some of these are on exhibition in Orton Hall at Ohio State University.

The animal life of the previous periods continued through the Carboniferous. Trilobites, which had survived from the earliest geological time, however, began early to disappear, and at the close of the period became extinct. Scorpions were abundant, and the first spiders appeared. The carboniferous forests swarmed with dragon flies, some with a spread of wing of two feet or more. Flies, crickets, locusts and cock-roaches abounded. Flowering plants had not appeared, nor the insects that love to explore their honey depths. The strange fish, the ostracoderm, that combined in its individual make-up some of the characters of the invertebrate and the fish, a sort of connecting link between the two, permanently disappeared.

The vertebrates before the close of this period had "followed the arthopods and the mollusks upon the land and had evolved a higher Type, adapted to the new environment." This type we know as the amphibians, the frogs and salamanders, with lungs for breathing the air and limbs for moving on the land. They were the connecting link between the fish of the sea and the reptiles that later pervaded the land. The amphibians of this period differed in many respects from those of our own. They wore an armor of bony scales that protected them from beneath and sometimes extended over their backs. The Carboniferous formations in Ohio are divided mainly into the Mississippian and the Pennsylvanian. The former was first formed. At its close the interior sea had still farther receded. Fulton, Williams and Defiance counties were now permanent dry land. The eastern shore line, beginning with Trumbull County, passes through Mahoning, Portage, Geauga, Summit, Medina, Wayne, Stark, Holmes, Coshocton, Muskingum, Licking, Perry, Fairfield, Hocking, Vinton, Jackson and Scioto counties.

The Pennsylvania includes a further extension into the south-eastern part of Ohio. The shore line at its close had become considerably shortened. It then passed from the southern boundary of Jefferson County, through Belmont, Monroe, Washington, Noble, Morgan, Athens and Meigs counties. The territory included in the Pennsylvanian is very rich in bituminous coal.

The remaining portion of the state was soon out of the marshy remnant of the inland sea, and Ohio's land formation was complete. This remnant, which was assigned to the Permian period, was also rich in coal measures. The forests of Lepidodendron and Sigillaria became rare and the Calamites became extinct. The trees were replaced by tree ferns and conifers. Plant and animal life went through many changes. A remarkable increase in the number and size of reptiles of this period is noteworthy, though for convenience they are often classified with the following period.

It must not be concluded, since the Ohio country was permanent dry land, that it was not subject to subsequent changes. its evolution from the primordial bed rock of the epicontinental sea into permanent dry land has been briefly traced.

35:2 GLACIAL PERIOD IN OHIO (Evidence of Ice Sheet)

OHIO ARCHAEOLOGICAL AND HISTORICAL PUBLICATIONS Vol. 1, Pg. 171, Pgh 2, L 3-11, Pgh 3, L 1 only, Pg. 172, L 9-34, Pg. 177, Pgh 2, L 7-23, Pg. 178, Pgh 1-2 L 3. Pg 179, Pgh 2, L 1-4

The evidence is conclusive that, at a comparatively recent period, the northern portion of Europe and America were covered with a vast mass of slowly moving ice, pressing down from the direction of the north pole towards the warmer latitudes. The origin of this ice (like that of the glaciers still remaining in the Alps and other mountain ranges, and still covering a large part of Greenland), was doubtless in the continued accumulation of snow over the glaciated region in excess of the melting power of the summer sun. This implies a climate both cool and moist. Into the speculations concerning the changed condition in the meterorological forces, I need not enter.

The extent of the region over which this ice sheet spread is now pretty accurately known.

Beginning at New York city, and omitting the minor features, the line marking this southern boundary runs N.W. to Salamanca, N.Y., thence S.W. to Carbondale, Ills., and thence N.W. to the neighborhood of St. Louis. To this limit the ice of the glacial period continued in its southern movement, grinding down the elevated surfaces and filling up the depressions of the country, and bringing its vast burdens of granite rocks from the north. As it withdrew, the ice in melting left its enclosed solid material which it had picked up along its long journey (constituting the boulders and hard-heads, or nigger-heads, as they are sometimes called), to mark its former presence. In the rear of the retreating ice there also appeared the prairie region, which had been planed and leveled by the moving mass, and by subsequent water deposits. The whole of the region north of this boundary line is now covered with an unstratified deposit of clay, sand, gravel and boulders. In this so-called "till" the constituent elements are uniformly of northern origin, and frequently from distantly separated points, granitic pebbles from Northern Canada being mingled in one indiscriminate mass with the local pebbles of Southern Ohio, and with others from intervening points. Another sign of glacial action consists in the striae or scratches which, all over this region, characterize both the stones included in the till and the surface of the underlying rock.

It is of great interest to know that when man, in a state of development similar to that of the Eskimo, was hunting the mastodon, and the reindeer, and the walrus in the valley of the Delaware, the ice-front extended in our own State as far south as Cincinnati. At that time the moose, the caribou, the musk-ox, and the reindeer ranged through the forests and over the hills of Kentucky. And if my theory of a glacial dam at Cincinnati can be entertained, there was for a period a long, irregular lake occupying the valley of the Ohio and its tributaries, rising to the top of the bluffs in all the lower portions of the valley above Cincinnati, and being as much as three hundred feet deep at Pittsburg. The explorer at that time, coming up from the south, would have encountered an ice wall along the line which I have marked as the glacial margin; and upon ascending it would have had before him naught but such icy wastes as recent explorers have found in the upper portions of Greenland, far along towards the north pole.

Ohio also affords abundant opportunities for estimating approximately the date of the close of the glacial period. Light upon this question promises to come from three classes of facts: 1st. The recession of waterfalls in streams whose courses have been changed by the deposition of glacial debris. Such streams occur most frequently in the northern part of the State. The streams emptying into the Ohio River for the most part occupy their old valleys, since they were, all through the glacial period, the natural outlets of sub-glacial streams; but in the northern part of the State, where the streams flowed in an opposite direction from the ice movements, the change of the river beds has been almost universal. The old channels were filled up with glacial debris, and, upon the retreat of the ice, it was a mere chance whether the rivers should flow in their former channels or not.

The former outlet for Lake Erie was so completely filled and buried that its course is only conjectural. Before the glacial period there was no Niagara Falls and no Lake Erie.

The various streams like Black, Rocky, Cuyahoga and Chagrin rivers, afford similar, but more imperfect, opportunities to estimate this period. At Elyria the falls of the Black River have receded since the glacial period a trifle more than two thousand feet.



The great ice cap, which covered Northeastern North America during the Glacial period, is estimated to have been about two miles thick in the region northeast of the Great Lakes. The weight of this great mass caused it to creep gradually toward the ocean on the east and toward the south, where the pressure was less.

In this relentless advance it ground off the hilltops and filled up the valleys, changing the region south of the Great Lakes from one of hills and valleys to a broad plain. The ice sheet came to an end some distance north of the Ohio River, and from its margins southward the hills remained undisturbed. The hilly country around Cincinnati furnishes a picture of what much of the state would be like, but for the glaciers.

The moving mass of ice, with its burden of boulders, gravel and powdered rock, wiped out old river valleys, changed the courses of streams,and quite remade the surface geography of Ohio. Some of the old river valleys, as the Miami River north and south of Dayton, and the Mad River east of Dayton, were filled in with this glacial debris to a depth of more than 200 feet.

In some parts a new surface soil was left, composed of this groundup rock, known as glacial till. On other great areas the limestone rock was left bare. As the years passed, the lime was leached out by the rains, and the remaining impurities of the limestone were left behind to form the fertile residual soils of central Ohio.

Not only did the ice sheet change the course of rivers, but it largely wiped out the local drainage. When white men first visited the central part of the state they found a densly wooded plain, poorly drained in many parts, and breeding mosquitoes and other insect pests. The malaria or "fever and ague" of the early days was carried by mosquitoes which bred in these undrained swamps.



When Lake Erie receded to its present level, its ancient bed was partly inclined like the rim of a basin sloping towards the water.

The mouths of the rivers were farther out than now, the lake was smaller in size and its shore line quite different. Where the shore was composed of marly clays, as it is along much of its outline, the waves made rapid inroads upon it and the soft materials were dispersed by currents that exist in all bodies of water. There is a tradition that when the French first coasted along the south shore of Lake Erie, the Indians remembered there was no outlet at the present mouth of the Cuyahoga River.

It discharged at the old mouth one mile west, and the point of the bluff extending westerly from the light house then interposed between the river and the lake. A mound, the remains of this point is represented in the sketch made by Capt. Gaylord in the year 1800. It remained at nearly the same height when I first saw it in 1827.

Operating upon such material as the blue marly clay, the encroachments of the lake were rapid. On the Canada shore opposite Cleveland the formation is the same and its destruction equally rapid. The remains of soldiers who were buried near the crest of the bank in the war of 1812 were in 1836 found to be at the water's edge. As the lake gained upon the shore its banks became higher, owing to the inclination of the land towards the water. The surface of the lake has a fluctuation of level which during a period of nineteen years, from 1819 to 1838, amounted to six feet and nine inches. When the water of the lake is high it has more erosive action upon the shore than when it is low. By the above analysis the blue clay deposit is shown to be principally fine sand, with merely clay enough to cement it. It also contains lime enough to give it a marly character.

When soaked with water the mass which in a dry state is compact and hard, becomes soft and yielding like quicksand.

During the highwater of 1838, the advance of the lake waters upon the town site was so rapid that the corporation took measures to protect it. By comparing the surveys of 1796 and 1842 there had been a general encroachment of two hundred and five (205) feet. In 1806 or 1807, AMOS SPAFFORD sent his hired man, with a yoke of oxen to plow a patch of ground on the margin of the lake, which must have been not far from the Marine Hospital. At noon, the man chained his team to a tree, fed them, and went home for dinner. Returning in the afternoon, his oxen were nowhere to be seen. Proceeding to the edge of the bank, the man discovered them still attached to the tree, quietly chewing their cuds, but the ground on which they stood had sunk between twenty and thirty feet, carrying with it some of the new furrows, the trees and the oxen. Thus a belt of land about twelve and one half (12 1/2) rods in width was lost, along the entire front of the city. In one hundred years this would at the same rate have amounted to twenty-seven (27) rods. It would, in about five hundred years, have undermined the PERRY monument. Before the close of a thousand years that part of town north of Huron Street would have disappeared.



When the early emigrants arrived at Buffalo creek they were at the end of roads. From Canandaigua to Lake Erie, there was only a summer trail for horses, along which sleighs and sleds could be moved, on the snow in winter. West of Buffalo there was nothing resembling a road, except an ancient trail of the savages, not much used by them, except in their warlike expeditions. Fortunately at the beginning of this century, the lake was low, causing a beach of clean sand at the margin of the water. Some of the streams were difficult to ford, but many of them were so much choked with sand at their mouths, that teams could cross. Not far outside of the shore line there is deposited a changeable sand bar, which forms at the debouche of all streams, where the force of the current is lost in the still water.

In the transparent waters of our northern lakes this bank is easily found. The emigrants thus made a passage of the streams by leaving the land, and driving their teams, apparently into the lake. If the water was rough, the waves breaking over the beach, they made a comfortable camp, above the bluffs in the woods near the shore, and waited patiently for better weather.

A few years afterwards, they were surprised to see this natural road submerged, by the the waters of the lake. This alternate appearance and disappearance, of the lake beach, has been a standing mystery to the pioneers and their descendants. It is a change due to the most simple and natural causes. The lakes are large ponds or reservoirs, through which the waters of many united rivers flow to the ocean. All rivers are affected by the seasons, but it is more noticeable in large ones like the Mississippi, the Ganges and the Amazon. A year or two of drought in the country about their main branches, always produces low water.

When other meteorological conditions occur, and one or more rainy seasons follow each other, the rivers are high. The Straights connecting our northern lakes are short rivers, not having capacity enough to discharge the surplus waters at once. This chain of lakes and their connecting outlets may be regarded as one great river, from tide waters at Quebec, to the source of the St. Louis river, in Minnesota. Like all large rivers, there is a spring rise and a winter fall, except in Lake Superior, where the rise occurs in August or September.

This annual rise, occurs in June or July, about the time of the annual flood of the Missouri and the Mississippi Rivers. It is much less in quantity, being only from twelve to sixteen inches; owing to the expansions, which act as reservoirs that must be filled; and which when full, require some months for their discharge. In the fall the surfaces of the lakes decline, simultaneously, as they rose. A smaller suppy of rain, and increased evaporation, together with a continual discharge towards the ocean, disposes of the surplus water of the spring rains. Then winter sets in, the supply from the streams is diminished by frost, and the lowest stage is reached in February or March.

Since the settlement of Detroit, in 1701, it is probable there had been no water as high as that of 1838. Timber which had grown to maturity on low lands, having an age of from one to two hundred years, was killed by this flood. From 1788 to 1790, Lake Erie is reported to have been very high. The old French inhabitants affirm, that a road which had long before been in use on the Detroit River, was rendered useless by high water in 1802, which agrees with the statements of early settlers in Ohio. In 1814, and from thence to 1820, Col. Henry Whiting, of the U.S. Army, made measurements, upon the surface fluctuations in Detroit River, which disclosed the lowest known state of the water to be in February, 1819. In more recent times some of the United States officers, connected with the construction of harbors on the lakes, kept water registers, some of them daily or three times a day. Of these were Capt. Macomb (now Colonel), Lieut. Judson, Col. J.B. Stockton, and Lieut.. Col. Kearny. The head of the Topographical Bureau at Washington, Col. Abert, refused all aid and countenance, to these observations, although they showed a change of level, which rendered their reported soundings to be erroneous by several feet; for want of a fixed or mean plane of reference. It was not until Capt. (now General) Meade took charge of the lake survey, that regular daily water registers, were officially kept on the lakes.



Grinders of the elephant and mastodon are common in the superficial materials, which cover the indurated rocks of the west. A grinder is said to have been found in blue marly clay on the West Side many years since. Remains of the elephas primigenius, the mastodon, megatherium, megalonyx, the horse, beaver, and some other animals, characterize the drift period. They existed prior to that geological ers, and through it to the alluvium, in which their bones are also found. They became extinct after the earth had taken its present condition. The elephant, whose bones were discovered a few years since, in digging the coal vaults of the Merchants Bank, was about twelve feet below the natural surface. Another grinder of an extinct elephant was brought to light in the grade of Champlain Street, which was about fifteen feet beneath the surface.


UNITED STATES DEPARTMENT OF THE INTERIOR, BULLETIN 818 Pages, 16, 17, 18, 20, 23, 67 Line 19, 73, 103

The valleys of the quadrangles are of varied topography according as they do or do not coincide in location with old pregalcial valleys. There are three types of stream valleys - old valleys, new valleys, and those that are part old and part new. Of the last mentioned type there are two subtypes - those in which the lower part of the valley is old and the upper part new, and those in which the lower part is new and the upper part old. Within these quadrangles the Cuyahoga is the only stream of the first type, but the river enters its old valley 10 miles south of this area, and all its upper course is new so that its valley as a whole belongs to the first subtype of the third group. The Rocky River is an excellent example of the second subtype, and Tinkers Creek is another. Euclid Creek and Big Creek flow in wholly new valleys.

The valley of the Rocky River presents a strong contrast to that of the Cuyahoga. The upper part of its East Branch also follows an old valley, whose course across the Cleveland and Berea quadrangles is plainly shown on the geologic maps. In general appearance this part of the valley is like that of the Cuyahoga - broad and with high rock walls, though not so deep as the Cuyahoga Valley. East of Strongsville the river forsakes this old valley, and thence downstream the valley has an entirely different character. Above Berea it is developed in a weak shale, is about a quarter of a mile wide, and is flat bottomed and bordered in places by nearly vertical walls of shale 10 to 30 feet high, decreasing in height northward. At Berea the stream flows in a narrow trench in sandstone and a fall and short gorge occur just north of the town, where the stream cuts through the sandstone into the shale below. From this point to the mouth of the river the valley is flat bottomed and steep walled, in a few places as much as a quarter of a mile wide, and has vertical walls of shale 100 feet or more in height. The West Branch has a similar fall and gorge at Olmsted Falls. Where the two branches come together at Olmsted, two prominent, isolated rock hills occur in the middle of the valley. They are quadrangular and bounded on all sides by precipitous shale bluffs. There are remnants of the shale promontory between the two branches of the river, which long ago came together below the hills, later cut across between them, forming the north hill, and later still came together as they now do.

At Kamms the stream crosses the old valley, which had been entirely filled with glacial drift, and here its present valley widens to three-quarters of a mile and its walls are of glacial drift and less steep than above. At the big bend at Rockport the valley reaches the east edge of the old filled valley, and the west wall of the present valley consists of drift and is in strong contrast with the shale cliff that forms the east wall.

The Rocky River is a much smaller stream than the Cuyahoga, though no measurements are known of its volume. The source if the East Branch is not more than 30 miles south of the lake and, except the headward part, it flows directly toward the lake. With the East Branch it is about 35 miles long and has a gradient of about 18 feet to the mile. Across the Berea quadrangle the West Branch falls about 10 feet to the mile. This is two and one-half times the Cuyahoga gradient, and the discrepancy is due chiefly to the differences in the two valleys, which have already been described.

Borings along the Rocky River, although showing a channel cut about 200 feet below the level of Lake Erie, have not given evidence of excavation to a level corresponding to that on the Cuyahoga Valley. It is possible, however, that borings have not penetrated to bedrock in the deepest part of the preglacial Rocky River channel, for only a few borings have been made along its course. The valley of the preglacial Rocky River makes a gap of more than a mile wide in the shale bluff where it enters Lake Erie, a short distance west of its present mouth, so that many borings are needed in order to test its depth fully.

The preglacial Rocky River is followed by the East Branch across Strongsville Township, but thence the preglacial channel runs northward through Middleburg Township, passing east of Berea and embracing the headwater part of Abram Creek. It crosses to the west side of the present stream directly west of Kamms and continues a short distance west of the river from that point to the lake. The gap in the shale bluff west of the mouth of the present stream was interpreted by Newberry as marking the channel of the pregalcial Rocky River, but the course of the channel was first traced by Dr. D. T. Gould, of Berea, several years later.

As the ice melted out of the Maumee and Erie Basins in northern Ohio and neighboring parts of Indiana, Michigan, and Ontario, ponding of water began with a small lake at the extreme west end of the Maumee drainage basing and other small lakes in the southern tributaries of Lake Erie, including one in the Cuyahoga Valley. As the melting of the ice continued, these small lakes were drawn down to the level of a large lake known as glacial Lake Maumee (pl. 11), which at first discharged into the Wabash Valley past Fort Wayne, Ind., and later across the Thumb of Michigan into Grand River Valley and thence into the Lake Michigan Basin.

When Lake Maumee was at its lowest level the Rocky River entered the lake immediately north of Olmsted. For 3 miles farther down the river there is on the left or northwest bank a deposit of sandy gravel similar to a natural levee which may have been brought in by the river to fill a lagoon south of the Maumee bar along which the electric railroad runs from North Olmsted eastward. It is probable that this deposit was not extended down the valley until the bar had been developed as far down as the vicinity of the line of Dover and Rockport Townships, for up to that time the lake waves were free to extend clear to the river. When the bar had been developed, the shallow waters of the lagoon were entered by the strong current of the stream, and the stream then extended its deposits into the lagoon and thus built the supposed natural levee. In doing so it reworked some of the material that had been developed by the lake, so that this strip of sandy gravel is a combination of lake and stream work.

When the lake rose to the higher level the water covered this part of the Rocky River Valley and extended up both branches of the river to 775 or 780 feet above sea level. On the East Branch its limit was at Berea; on the West Branch it was as far up as Westview. The stream at this higher lake stage made no conspicuous deposits where it entered the lake, though a thin deposit of pebbly material is found on the till about half a mile above Westview on the west side of the West Branch. On The East Branch in Berea, near the falls by the railroad bridge, there is also more or less waterworn material, which was probably laid down by the river while the lake stood at its highest level.

Since the Wisconsin ice sheet disappeared from the Cleveland district the streams have been subject to several distinct base-levels, owing to the changes in the level of the lake waters described above. At each succeeding lower stage the streams were extended to the new position of the shore line. At each succeeding rise in the lake level the lower courses of the streams directly tributary to the lake were flooded and probably partly refilled with sediment, and the opening of the valleys was by so much retarded. Owing to the complexity of the relations between the streams and the shifting base-level it is difficult to differentiate clearly the history of each stream at each stage of the lake. The valleys of to-day represent the net result of the process of development.

The Cuyahoga River has cut a crooked flat-bottomed valley 100 to 180 feet deep, bordered by steep bluffs and ranging in width from about a mile down to scarcely one-fifth of a mile. Most of this cutting has been done in unconsolidated material, a large part of which is laminated clay. Only at three places - near Boston, Brecksville Station, and Tinkers Creek - is the preglacial rock bluff exposed. North of Brecksville Station the valley cuts across a projecting rock point, and there its trough is very narrow.

The Rocky River has worked mostly in shale. Except where the river follows or crosses its preglacial valley, it occupies a narrow, steep-walled channel. Down to relatively recent time the junction of the East and West Branches was north of two rock prominences north of the road running east from Olmsted. The channel west of these prominences, about 100 feet deep, was probably cut by the West Branch and later abandoned. The diversion through the gap at the road east of Olmsted is said to have occurred at about the time the first settlers came to this region. The diversion through the passage between the rock prominences was evidently much earlier.

The erosion on tributaries of the Cuyahoga and Rocky Rivers has been relatively slight, except in the lower courses, where they are coming into adjustment with the deep valleys of the major streams. There are usually cascades where the streams pass out from the sandstone to shale formations. Such cascades are conspicuous where the streams pass out of the Berea sandstone. Excavation in the rock formation has been very slight except as stated above. The drainage of the elevated upland is to a great degree rudely coincident with the preglacial lines, but on the lowlands the preglacial drainage channels have been so completely filled with drift deposits that most of the present streams follow new courses.