THE THICKNESS OF THE DRIFT DEPOSITS IN THE AREA SURROUNDING DAYTON
[Photo: The southwestern margin of the gravel ridge area, viewed from the Bellbrook road. The abandoned barn on the top of the Walden ridge is seen at the extreme right. The gap through the western ridges east of the Emrick farmhouses is located at the extreme left.]
83. Solid Rock Beneath a Thin Covering of Soil
Some parts of Montgomery county are remarkable for the frequency with which solid rock is exposed beneath a very thin covering of soil.
For instance, in the area extending from a mile south of the Soldiers’ home northwestward toward Trotwood and Amity the rock frequently is covered by only 2 to 5 feet of soil. Along the stream courses, and along the brows of the hills, exposures of rock are frequent. The exposures consist chiefly of the Brassfield limestone, and of the overlying divisions of Silurian limestone. The Springfield limestone frequently is exposed in quarries opened for building stone. Here usually less than 5 feet of soil is removed in order to get at the solid rock. [p. 175]
Even in those parts of the country in which the rock does not appear at the surface, solid rock may be present within a short distance from the top of the soil. For instance, in the area extending from Amity westward, through Pyrmont, to the western border of Montgomery county, no rock exposures are known, but rock is struck at a moderate depth in wells, and several quarries formerly were in operation. Two mile west of Amity, in the middle of section 15, rock was struck in a well within 6 feet of the top of the soil, and a quarry formerly was in operation south of the road. Three-quarters of a mile westward, another quarry formerly existed, and a third quarry was located south of the road, a mile east of Pyrmont, along a stream channel. From Pyrmont southwestward there is a rather thick deposit of soil and of glacial deposits covering the rock, wells 30 to 50 feet deep not reaching the same, but a mile north of the Dayton-Eaton pike, on the Montgomery county line, the Brassfield limestone is exposed in the creek bed. The quarries between Amity and Pyrmont were opened up in rock belonging to the Springfield or overlying divisions of the Silurian limestones.
Rock lies close to the surface of the soil also in the area west of the Stillwater river, between Englewood, West Milton, and Ludlow Falls, and from Englewood eastward toward Chambersburg. It lies close beneath the surface also west of the Miami river, at various localities on the high ground between Tadmore, Tippecanoe, and Cowlesville. It is covered by a comparatively thin layer of soil also east of the Miami river, from a point 2 miles north of West Charleston southward for 7 miles, and thence eastward toward Brown station, Brandt, and Huffeysville.
About a mile north of Belmont, southeast of Dayton, the solid rock is close to the surface of the soil, but in the quarries formerly operated southeast of the asylum and at Beavertown it was covered by about 20 feet of sand, gravel and clay.
It should be noted that in all of these cases in which the solid rock is found beneath this cover of soil, this soil consists chiefly of clay. It evidently represents a glacial till deposit. The underlying rock surface usually is distinctly striated, and the till deposit apparently represents whatever material happened to be embedded in the bottom of the ice during the [p. 176]
[Photo: Ripple-marked surface of limestone, belonging to the Richmond group; exposed about a mile east of Winchester, Ohio. Similar ripple marks are common on the limestone layers 5 miles west of Middletown, a mile south of Jacksonburg.]
final stages of the melting of the glacial ice. It is not a deposit from the margin of the glacial ice sheet, but from its bottom. In this sense, it might be called a ground moraine, rather than a terminal moraine deposit.
It will be deposited that all of these areas, in which the rock lies close to the surface of the soil, occur on the higher levels of land, not in the valleys. In Montgomery county, this is equivalent of saying that the thin soil covers are found chiefly on Brassfield, Dayton, Springfield, or Cedarville limestone, or on some other division of the Silurian group of rocks, since [p. 177] these rocks underlie all of the high levels in the county. Since they are harder than the underlying Cincinnatian strata, and are less readily eroded, they frequently form the brows of the hills and the margins of the flat hill lands bordering the deeper valleys.
Glacial deposits are likely to be thinned where the glacial ice was pushed up over the brow of a hill on rising from a fairly deep valley. This accounts for the numerous exposures of the Brassfield and overlying Si-
[Drawing: Vertical section from Beavertown to Soldiers’ Home, across the Miami valley, indicating that the gravel ridge area in the Hills and Dales and south of Calvary cemetery lies chiefly below the level of the hills bordering the preglacial valley. The drift filling the valley consists chiefly of gravel; that on the hill tops is chiefly till. The underlying rocks and the horizon of a few of the characteristic fossils also is indicated. Localities where the same rocks and fossils may be found freely exposed on going from Dayton toward Cincinnati are mentioned. The present valley of the Miami river is that part lying west of the hills at the Crume Brick Company plant.]
lurian limestones along the hill front south of Wolf creek, from the vicinity of the Soldiers’ Home to a point 3 miles southeast of Brookville. On the northern side of this valley, exposures are few. While rock exposures are common along the hill front east of the Miami river, from a point southeast of Tippecanoe to beyond Tadmore, and thence eastward both toward New Carlisle and Huffeysville, no outcrops are known along the eastern front of this hill land, between Huffeysville and a point two and a half miles southwest of New Carlisle. Along the margin of the large triangular mass of hill land beginning two and a half miles east of Dayton, east of the Montgomery county line, rock exposures are almost unknown ex- [p. 178] cept along the northwestern margin, extending from New Germany northward. It should be remembered that the ice sheet in Montgomery county moved about 15 degrees east of south, and hence the northwestern boundary of any hill land was the part which bore the brunt of the thrust of the ice sheet during its motion in a general direction southward.
Where the ice sheet crossed a comparatively narrow and deep valley, the rock along the top of the hill land west of the valley is also likely to be covered by little soil, apparently owing to the downward flexure of the ice sheet. Such an area occurs west of the Stillwater river, between Englewood and Ludlow Falls, and more isolated localities occur west of the Miami river, near Tadmor, half way between Tadmor and Tippecanoe, and northwest of Cowlsville.
84. Thick Deposits of Gravel, Sand, and Clay Beneath the Flat Lands Occupying the River Valleys; and the Preglacial Drainage of Southwestern Ohio
It is a familiar fact that at many localities wells have been dug or bored through considerable thicknesses of gravel, sand, and clay without striking solid rock. What is not familiar to the average observer is that, no matter how thick the overlying deposit of gravel, sand, and clay may be, there always is rock beneath. In other words, the interior of the earth consists of solid rock. The gravel, sand, and clay forms merely a relatively thin coating which covers this rock interior.
Since, in glaciated areas, these deposits of gravel, sand, and clay were transported chiefly by the glacial ice or by the streams issuing from its front, they commonly are known as drift. Naturally this drift is thickest in the deeper preglacial river valleys. Hence, in order to get some idea as to the general appearance of these preglacial valleys it is necessary to determine to what extent they have been filled with drift and then to imagine how they would appear if all of this drift were removed.
Within the valley of the Miami river the following thicknesses of drift have been found beneath the comparatively flat lands bordering the present river channel. Near Piqua, the thickness of the drift, down to the solid [p. 179]
[Map: Preglacial Drainage of the Little Miami River According to Prof. J. A. Bownocker]
rock, is 170 feet; at Troy, 133 feet; at Osborn, 207 feet; in Dayton, at the corner of First and Findlay streets, 247 feet; at Miamisburg, 181 feet; and at Hamilton, 210 feet. The thickness of the drift at Osborn is included in [p. 180] this brief list since, in preglacial times, the channel of the Miami river is believed to have extended from Troy toward New Carlisle and Osborn, rather than by way of Tadmor and Taylorsburg, as at present.
If now the elevation above sea level of the various towns here mentioned be determined, and if from this the various thicknesses of drift be subtracted, in order to ascertain approximately the elevation of the river bottom at each locality during preglacial times, the results are between 700 and 720 feet for Piqua, 700 feet for Troy, and 600 feet for Osborn. This lower elevation for the preglacial river channel at Osborn certainly does not favor a northward flow of the Miami river, from Osborn toward Troy, in preglacial times, as sometimes supposed.
From Dayton southward the corresponding results would be 520 feet at the corner of First and Findlay streets in Dayton, 520 feet in the northern part of Miamisburg, and 380 feet for Hamilton. These data also suggest a southward flow of whatever stream occupied this part of the Miami valley in preglacial times.
It is reported that at St. Paris, 16 miles east of Piqua, a well was sunk a distance of 530 feet without striking rock. At a depth of 400 feet large pieces of wood and of bark and fragments of mussel shells were struck. The bottom of this well was approximately 685 feet above sea level. The bottom of the preglacial valley at Piqua is somewhere near 700 or 720 feet, it is evident that the bottom of the preglacial valley struck at St. Paris is lower. Whether this necessarily means a northward flow of the preglacial streams at Piqua and St. Paris I am not prepared to state.
Professor John A. Bownocker, the present state geologist, gave this subject more detailed attention, and in 1900 published the map here reproduced. In this map the word “col” designates those narrow parts of the present river channels at which in preglacial times the drainage areas of neighboring basins were separated. In other words, at these points, in preglacial times, the streams flowed in opposite directions. According to this map, in preglacial times, the upper part of the Ohio river and the Licking river joined northwest of Cincinnati and flowed toward Hamilton. That [p. 181] part of the present little Miami river which lies south of Foster, connected with the same drainage basin. Todds Fork, and that part of the present Little Miami river lying between Fort Ancient and Foster drained westward into the broad valley now connecting with the Great Miami river valley south of Middletown. Here it was joined by the drainage of the Great Miami river valley from points at least as far north as Taylorsburg and Harshmanville. The remainder of the Little Miami river, from Fort Ancient northward, flowed northward by way of Alpha, Osborn, New Carlisle, Tippecanoe, Troy, and Piqua toward the headwaters of the Wabash river, being joined by the preglacial river passing through St. Paris somewhere in northern Ohio. According to the map this junction took place near Celina.
The reasons for assuming these directions for the preglacial drainage of southwestern Ohio are given by Professor Bownocker in his paper on the History of the Little Miami River, published by the Ohio State Academy of Science. For our present purpose it will be sufficient to call attention to the fact that the map leaves unsolved as to what becomes of the Ohio and Licking river drainage after reaching Hamilton, and of the Todd Fork drainage after reaching the vicinity of Middletown. Evidently the map is intended to suggest that the outlet for this drainage must be toward the northwest, but that the precise path for this outlet has not yet been determined. In the search for such an outlet it is interesting to note that exposures of rock ranging from the Brassfield limestone to the Springfield limestone are so frequent and the overlying soil is so thin in the area between the Soldiers’ Home and that part of Wolf creek which lies three miles southeast of Brookville that the possibility of any considerable preglacial valley through this region may be discounted. Farther west, Silurian limestone is struck by wells at shallow depths at various localities as far west as the creek one mile east of Pyrmont, and three quarries were formerly in operation, one at the eastern margin of section 15, one near its western margin, and a third along the creek one mile east of Pyrmong. Within this more western area the top of the solid rock averages about 990 feet above sea level. At Pyrmont, wells 50 feet deep do not reach the rock; but 50 feet below town level is still 990 feet above sea level. The [p. 182] drift continues heavy between Pyrmont and the valley of Twin creek, four miles westward, but Brassfield limestone is exposed at the 960-feet level four miles southwest of Pyrmont, along the Montgomery county line. Between Lewisburg and Eaton exposures of the Brassfield and overlying limestones are too numerous to make the former presence of a preglacial channel within this area probable. Between Eaton and Richmond there are a sufficient number of exposures of Brassfield limestone and of the immediately underlying parts of the Richmond group to eliminate this part of the territory also from a possible course of a preglacial outlet for streams flowing from the direction of Hamilton and Middletown. Since the line of Brassfield outcrops from Eaton reaches the southern border of Preble county southeast of Morning Sun, within seven miles of the Indiana state line, it is evident that the preglacial channel must be sought within the limits of Butler county. Here, however, numerous exposures of Richmond strata intervene to points considerably beyond Oxford. It is probable that the basal parts of the Richmond formation are continuous as far as the area immediately west of the southwestern corner of Butler county. When it is realized that the rock beneath the preglacial valley at Hamilton is struck somewhere near the 380-foot level above sea and that the basal layers of the Richmond west of Hamilton are at least 775 feet above sea level, the difficulties of finding a preglacial outlet in this direction may be appreciated.
For the present, therefore, we are obliged to conclude that a westward drainage of preglacial waters from the region of Hamilton and Middletown through Butler, Preble, or Montgomery counties, seems highly improbable. In the meantime it must be acknowledged that such a map as that prepared by Professor Bownocker for the drainage of the Little Miami river, especially of its upper waters, is highly stimulating to further research. It emphasizes the separation of the drainage of that part of the Miami river which lies north of Tadmor and of that part of the Mad river which lies east of Simms station from the general drainage of the Miami river from Dayton southward, and places the main channel along Alpha, Beaver creek, Osborn, New Carlisle, and Tippecanoe. This was regarded as the preglacial channel of the upper waters of the Miami also by Professor Edward Orton, in his reports on Clarke and Miami counties, published [p. 183]
[Map: Map contrasting the width of the pre-glacial valley extending from Tippecanoe by way of New Carlisle, Osborn and Fairfield toward Beaver creek with the present channel of the Miami River at Tadmor. The high ground bordering the valleys is outlined by dotted lines.]
more than 25 years earlier. Orton, however, at that time thought that the drainage through this preglacial channel was southward.
85. The Huffman Prairie Area
The argument in favor of the separation of the drainage of the Miami river north of Tadmor and of the Mad river east of the Montgomery county line, during preglacial times, from that part of the Miami river which extends southward from Dayton is chiefly based upon the narrowness of these river channels at Tadmor and at the Montgomery county line, and on the [p. 184] comparatively shallow depth at which the underlying rock is believed to occur. Since a much wider valley, covered with thicker masses of drift unobstructed, the former drainage is considered to have followed the wider and deeper more eastern preglacial drainage basin, rather that the present channel.
South of Tippecanoe, the valley of the Miami river narrows rapidly as though approaching the headwaters of some stream, instead of doing the exact opposite. At Tadmor, the high rock walls on the two sides of the valley are only three-quarters of a mile apart at the top, and near their base the underlying strata approach each other within half a mile. Southward, this narrow gorge continues for about a mile and then it widens out rapidly again, south of Taylorsburg. To the student of physical geography the topography here resembles that of two former stream valleys flowing in opposite directions from some point between Tadmor and Taylorsburg.
East of Tippecanoe, however, there is a very broad preglacial valley, occupied at present only by an insignificant stream, Honey creek, and south of New Carlisle the continuation of this broad valley is drained by a stream not even large enough to receive a name. Along this eastern preglacial channel the rock walls are at least two miles apart.
This ancient preglacial valley at present is deeply filled with gravel, sand, and till deposits. The highest part of the watershed separating Honey creek from the little stream flowing southward toward Osborn is located southwest of New Carlisle and is 870 feet above sea level. If, after the melting back of the glacial ice front the waters imponded in the areas south and southeast of Tippecanoe found a lower outlet along the watershed between Tadmor and Taylorsburg than 870 feet, they would have taken this western channel in place of the former eastern preglacial valley. In the course of time the watershed between Tadmor and Taylorsburg would be cut down to its present level.
In a similar manner, the channel of the Mad river at the eastern margin of Montgomery county occupies a valley only about half a mile in width, while in both directions from this point the valley widens rapidly. Since the watershed between the Mad river and Beaver creek, 2 miles southeast of [p. 185] Osborn is 850 feet above sea level, the waters covering the Huffman prairie area southwest of Osborn would cut through a new channel by the present exit from the prairie area only if they found the western watershed below the 850-foot level. At present the hill tops bordering the western exit rise to the 920-foot level, but between these hill tops there may have been a depression descending to less than 850 feet, in preglacial times.
If the Mad river, during the late glacial times was obliged to cut for itself a new channel through the hill-front along the eastern line of Montgomery county, west of Simms station, then for a time the waters might have been imponded in the Huffman prairie area extending from Medway, Osborn and Fairfield southwestward. Even in comparatively recent years all of this area was very marshy, and if it were not for the extensive drainage ditches, most of it would be marshy to-day. Water is struck within moderate distances of the surface of the ground, and the total quantity present in the thick deposits fo underlying sand must be enormous.
86. Sand and Gravels as a Source of a City Water Supply
It would be interesting to determine to what extent Dayton has access to the enormous quantities of water present in the sands and gravels underlying the Huffman prairie area, east of the Montgomery county line. At present our water is withdrawn from a narrow area extending from the vicinity of the waterworks, within the limits of Dayton, along the Mad river as far east as the point where the river is crossed by the Erie railroad, north of the northern extension of Huffman hill. This point lies 3 miles southwest of the gap by means of which the Mad river leaves the Huffman prairie area. Of course, at present we are securing chiefly such water as seeps from the bed of the Mad river downward through the underlying sands and gravels. No attempt is made to secure any of the water outside of this stream channel, and the upper wells, of course, tend to exhaust those farther down the stream. Running river water from the dam at Findlay street through the canal into the old Bimm ice pond of course adds to the water supply of the wells in the vicinity of the pond since the water naturally will seep through gravel and sand quicker when under greater pressure, [p. 186] and this increase in pressure will be proportionate to the height of the water in the pond over the top of the water surface in the river. The bottom of a pond acts virtually as a filter, and it becomes a question whether such a filter within the confines of a city and subjected to all of the possibilities of contamination is advisable. Sooner or later it may become necessary to consider the erection of an extensive artificial filtering system.
Pumping naturally reduces the level of the water in the wells below that of the water in the immediately surrounding territory, and hence the water from this surrounding territory seeps through the sand and gravel toward the wells. Most of this additional water comes, of course, from the river channel, directly above, and this is the only reason for placing all of the wells so close to the river. The seepage of water through sand and gravel is so slow that, for a large supply, it is necessary to depend upon a supply close at hand, requiring a minimum distance for seepage.
Seepage through sand and gravel is supposed to free the water from dangerous germs. The effectiveness of this form of filtering might readily be called in question, although all reports on the water supply of Dayton hitherto have been very favorable.
The rate of flow of water within sands and gravels, of course, is very slow. Some people seem to think that there are underground streams running along channels comparable with those flowing through the underground passages of caves. Nothing could be farther from the truth. The largest underground channels that exist in sands and gravels are the small spaces present between the sand grains and the pebbles, as exposed in any open sand or gravel pit.
The direction of flow or seepage of underground water, in general, is practically the same as the direction of flow of the river water, down the valley followed by the stream, excepting in so far as there also must be a lateral seepage from the higher land along the valley toward the river channel. In a similar manner water must seep from the surrounding land toward any active well, since the water in the latter represents a low level, on account of the continual withdrawal by pumping.
Wells placed in a series along a river channel attack chiefly the same source, that part of the river water which sinks into the sands and gravels [p. 187] from the overlying river bed, excepting as new supplies come in much more slowly from the sides of the valley. Hence the importance of keeping track of the sanitary conditions not only in the immediate neighborhood of the wells, but also up-stream and also for a considerable distance from the river margin.
The adequacy of any water basin as a source of supply is also a problem. So far we have been tapping merely the supply of water furnished by the flat lands along the Mad river, extending from within the boundaries of the city as far eastward as Harshmanville. It is a question to what extent
[Drawing: Vertical section from the hills east of the southern end of Miamisburg to Germantown, indicating the narrowness of the valley at Miamisburg. The same vertical scale if employed as for the section through the Hills and Dales area. A pre-glacial valley is supposed to exist beneath the drift deposits in the Dry Run valley, but as a matter of fact the thickness of the drift here is known. However, no exposures of rock are known between Carlisle and Germantown, within two miles east of Twin creek, nor from the wide area between Germantown and Ellerton, nor between Ellerton and Alexandersville.]
The withdrawal of the water from the wells recently opened up in the vicinity of Harshmanville will add permanently to the water supply at Dayton, and to what extent it will lessen the waters furnished by the wells farther down stream, in the vicinity of the waterworks.
Farther eastward, in the Huffman prairie region, there is, of course, a large supply of water, hitherto practically untouched. Although apparently merely an area farther up the same river basin, the Huffman prairie in reality represents geologically a quite distinct basin, connected with the flat land surrounding Harshmanville only by a comparatively narrow channel, along which the seepage channel of sand and gravel appears to be of only moderate depth. This channel, two miles northeast of Harshmanville, apparently leaves untouched all excepting the highest levels of the water which is seeping through the Huffman prairies, so that the latter [p. 188] offer great sources of additional supply for the growing needs of the city. Wells sunk in the vicinity of Simms station or the Wright aviation field would attack a distinctly new source of supply.
87. The Alexandersville Bottom Lands
The present channel of the Miami river, at Miamisburg, is remarkably narrow and steep-sided, compared with the general width of the valley both
[Map: Map contrasting the width of the valley of the Miami river at Miamisburg with the valley farther northward and southward. The high ground bordering the valleys is outlined by dotted lines. The hypothetical pre-glacial valley east of Germantown, supposed to be the pre-glacial path of the Miami river, is indicated by broken lines. At present this path is heavily covered with drift.]
north and south of the town. At the southern end of Miamisburg, the hill cut by the Big Four railroad is only about half a mile distant from the nearest part of the hill-front on the western side of the present river channel. However, 3 miles west of Miamisburg is a much wider preglacial valley, at present deeply covered with drift and occupied only by an insignificant stream, Dry Run. The headwaters of Dry run are separated from that part of the Miami river valley which lies west of Alexandersville and West Carrollton by a watershed which is about 770 feet above sea level. At present, the hills at the narrow part of the valley at Miamisburg rise 900 feet above sea level. Therefore, if the channel through Miamisburg was not open in [p. 189] preglacial times, it must have been at least below the 770-foot level, if resulting from the escape of imponded waters.
North of Miamisburg, the bottom lands of the Miami river are remarkably flat and cover wide areas. These are the Alexandersville flat lands, which extend northward as far as Dayton. Topographically, they correspond to the Huffman prairie area, east of Dayton.
The most northern rock exposure along the hill front northwest of Miamisburg occurs about a mile from town. No exposures are known from the broad area extending from West Carrollton westward toward Ellerton, and beyond, to the headwaters of Dry run. No exposures occur moreover from this point southward, along the preglacial valley occupied at present by Dry run, excepting on the western side of Twin creek, south of Germantown. Hence, the former use by the Miami river of the channel by way of Dry run, instead of by way of the present channel through Miamisburg is regarded as not probable.
88. Thick Deposits of Gravel and Sand Above the Level of the Flat Lands in the River Valleys
In addition to the thick deposits of drift underlying the flat bottom lands bordering the rivers in the existing valleys, there are considerable thicknesses of gravel and sand also above the level of these bottom lands, especially along the sides of the preglacial valleys. This is to be expected, since gravel and sand are stream deposits, and stream deposits are to be expected in valleys, rather than on the hills.
The peculiar conditions under which streams issued from the margin of the glacial ice sheet caused some of these streams to build up gravel and sand deposits on high land. For instance, west of the northern end of Catalpa drive, north of Dayton, there is a short gravel ridge, which at its highest point rises 70 feet above the glaciated top of the Brassfield limestone, and forms one of the conspicuous landmarks in this area. At present this ridge is being exploited for sand and gravel, and in a short time the highest part of the ridge, rising in the form of a steep knoll, will have been removed entirely. This ridge probably represents the deposit of a [p. 190] subglacial stream, near the margin of the ice sheet, and therefore had a history similar to that of the gravel ridges south of Dayton, here under discussion. Its chief interest lies in the fact that this subglacial stream evidently found an exit from beneath the ice sheet at higher levels than usual.
[Drawing: Vertical section from David church to the Narrows, four miles southwest of Dayton, across the Delco Dell gravel ridge area and the Miami valley. The present valley lies west of the Grand View ridge area. In pre-glacial times the valley probably extended as far east as the David church. The gravel ridges in the Delco Dell and Grand View areas lie below the level of the hills bordering the pre-glacial valley. The thickness of the drift filling the valley is unknown. The drift deposits within the pre-glacial valley are chiefly gravel, those on the hills bordering the valley are chiefly till.]
As a rule, the subglacial streams found their exits somewhere within the limits of the preglacial valleys, and the gravel and sand deposits which they heaped up rarely rise much above the level of the high hill land bordering the valley. For instance, the greatest area of sand and gravel in the vicinity of Dayton occurs in the area south of Dayton, from Carrmonte and the Calvary cemetery southward through the Hills and Dales, and the Delco Dell as far as Hole’s creek. This is an area 5 miles long and 2 miles wide within which the top of the gravel ridges often rise 100 feet above the level of the flat bottom lands, and within which the total thickness of the drift, down to the solid rock beneath, must equal locally at least 300 feet. The highest part of the gravel area west of the Cincinnati pike lies within the Calvary cemetery and is 940 feet above sea level. The highest part of the Adirondack ridge in the Hills and Dales area is about 925 feet, rising to 940 feet toward its junction with the Panorama ridge. The highest part of the ridge area on the Moraine farm also is about 940 [p. 191] feet above sea level. Within the Delco Dell grounds, none of the land rises above the 925-foot level, and this is the highest level within the gravel area southward, as far as Hole’s creek. A considerable part of the land along the Lebanon pike, however, lies above the 1,000-foot level, and this part is covered by gravel along its extreme western border. Farther east-ward, the deposit overlying the solid rock consists chiefly to till.
Thick deposits of sand and gravel occur in the hill area south of the Xenia traction line, between Shakertown and Alpha, but the tops of these gravel deposits rarely reach 1,020 feet, while this level is attained by a considerable part of the till-covered area a mile south of the northern margin of the gravel area. Gravel and sand are abundant in the hill area south of Fairfield and the Wright aviation field, but these gravel hills nowhere rise conspicuously above the level of the till-covered area southeast of New Germany. Enormous deposits of gravel and sand occur also along the valleys of Honey and Indian creeks, between Tippecanoe and New Carlisle, but the tops of the gravel hills rarely exceed 900 feet, while this altitude is reached by a considerable part of the till-covered area both north and south of the gravel area. Similar remarks might be made about the gravel areas east of Ginghamsburg and Chambersburg, on the western side of the Miami river; along the valley of Brush creek, 2 miles east of West Milton; and along the northern side of Wolf creek, southeast of Brookville.
89. Thick Deposits of Till
The deposits of till also appear to be thickest within the limits of preglacial valleys. At the bend of Twin creek, one mile southeast of Germantown, the exposed thickness of till equals 70 feet. At its bottom it rests upon a peaty layer containing cedar berries, fragments of wood, mosses, grasses, and sedges. At the Pinnacles, a mile northwest of Alexandersville, the total thickness of the till is at least 100 feet and probably equals 120 feet. Considerable thicknesses of till occur along the valley of Hole’s creek, about 2 miles east of Alexandersville. At the Doctor Scheibenzuber farm, a mile northeast of Delco Dell, a well passed through 180 feet of till without reaching the rock beneath. At a well bored at Delco [p. 192] Dell at least 120 feet of till was found beneath 75 feet of sand and gravel, without striking the underlying rock. Within the areas covered by the various terminal moraines the thickness of the till frequently exceeds 20 feet and sometimes equals 50 feet, but usually the thickest deposits of till appear to occur there where the glacial ice sheet passed from a high level
[Drawing: Vertical section across the Dr. Scheibenzuber farm in an east and west direction, with diagrammatic representation of till plastered against the eastern border of the pre-glacial valley by the southeastward moving glacial ice. At the Dr. Scheibenzuber farm a well penetrated 180 feet of till without striking solid rock. A short distance westward, gravels and sand overlap the till deposits and are well exposed along the valley southwest of the house.]
area into a deep, wide valley, or where, on leaving a wide valley, it pushed up against a steep hill area.
In general, the glacial ice sheet appears to have moved southward without any regard to the topography of the underlying country. It not only filled the valleys, but rose for hundreds of feet above the surrounding hills. While, in a general way, the ice may have moved downward on reaching a valley, and upward on ascending the opposite slopes, it is possible that to a large extent the upper part of the mass of ice, above the hill [p. 193] level, moved much faster than the lower part which was held back within the valley, and even may have sheared more or less across the latter. This may account for the slight deflection produced by valleys on the direction of the glacial striae. It must be remembered that, aside from the valleys, the general topography of the hill lands around Dayton is comparatively flat, the hills rising in all directions to about the same general altitude. Hence the sky line as seen from any tall building in every direction around Dayton appears comparatively straight, and not deeply indented by hills can no longer be distinguished and the individual hill summits appear to coalesce into a long, single, horizontal line. In other words, this part of southwestern Ohio may be regarded as an extensive plain deeply into by numerous rivers and streams. The motion of the ice across this plain was not greatly influenced by the valleys indenting the latter.
90. Many Boulders of Canadian Origin Are Without Glacial Scratches
The first thing to attract attention at the Moraine Park station, in addition to the beautiful natural surroundings, is the pretty waiting-room. Here numerous boulders of Canadian origin have been collected from the fields and used to produce irregular color effects in the outer walls of the building. Canadian boulders are used also for the protecting walls lining the stream channel southeast of the station, and for the chimney attached to the Deeds cottage, at the extreme northern end of the Delco Dell grounds. All of the supporting walls of Ridgeleigh Terrace are constructed of similar boulders.
Comparatively few of these boulders show flattened faces or parallel glacial striae, although many of them are strongly rounded. Most of these boulders, during their journeys southward, apparently were subjected to the rounding action of flowing water, at least during the final stages of their progress. During by far the greater part of their journey from their original Canadian homes, many of these boulders probably were transported embedded within the glacial ice, rather than pushed along at its bottom. In fact, if the boulders had been pushed along to any considerable [p. 194] extent at the bottom of the ice, flattened faces and glacial striae should be in evidence more frequently, notwithstanding the later subjection of many of these boulders to the effects of running water.
91. Boulder Belts
Evidently, the boulders at one time were very numerous. At some localities they were very much more numerous than at others. They were especially numerous along the outer border of the Eaton moraine. Formerly they were very abundant along the Troy pike, south of Chambersburg, but many have been moved since, for building purposes. They were abundant in parts of Dayton View, south of Liberty, near West Alexandria, and north of Eaton. In a north and south direction, across the Eaton moraine, the boulders were scattered over an area 2 to 3 miles in width. The east and west roads crossing this moraine often encountered numerous boulders for a distance of 4 or 5 miles. So numerous were the boulders, that the Eaton moraine was known as a boulder belt. In 1878, Professor Edward Orton recorded that near West Alexandria, on the farm of David Potterf, he had counted 1,200 boulders exceeding 2 feet in diameter to the acre, and stated that there were points where boulders were more numerous than this.
Boulders are numerous also along many of the the other moraines, but those along the Eaton moraine compared in numbers with any known in the Mississippi valley. They occur not only on the surface, but also enclosed within the underlying clays and gravels. Comparatively few occur more than 5 or 10 feet below the surface, suggesting that the boulders were carried along within the ice until they reached the terminal parts of the ice sheet, where they were dropped by the melting of the ice. Apparently many of these boulders were carried so far above the base of the ice sheet that they suffered less from rubbing than the main mass of rock fragments carried along in the basal parts of the ice. [p. 195]
92. High Points in Southwestern Ohio, Especially in the Vicinity of Dayton
The highest land in the state of Ohio is located about 50 miles northeast of Dayton, a few miles east of Bellefontaine. Here the highest altitude is 1,540 feet above sea level. High land is found also farther eastward, in Richland, Tuscarawas and Columbiana counties, but in no case does this land attain an elevation of 1,500 feet. The highest land southeast of Dayton occurs in the eastern part of Highland county, 55 miles away. Here several high hills or mountains are located, one of which reaches an altitude of 1,300 feet.
The highest land within 15 miles of Dayton is located southeast of the David church, on the eastern side of the Lebanon pike, and about 2 miles southeast of Delco Dell. Here the highest elevation is a few feet above 1,100 feet above sea level. The highest land northeast of Dayton is located about a mile southeast of West Charleston, and is 1,022 feet above sea level. Northwest of Dayton the highest land is located about 3 miles west of Brookville, and attains a level of 1,070 feet. Southwest of Dayton, the highest land occurs about five and a half miles west of Germantown, where it reaches a level of 1,030 feet above sea.
The elevation of the base fo the lamp post at the southern end of the Main street bridge is 755 feet above sea level. The average elevation of the land within the central part of the city is 740 feet. The cottages at Delco Dell are 160 feet above this level, and are freely exposed to the breezes from almost any direction. It is an ideal location in hot summer weather. The highest land in the southeastern corner of the Hills and Dales area is 40 feet higher, but is less abruptly elevated above the surrounding country.
The highest land north of Dayton occurs at the gravel pit west of the northen end of Catalpa drive, where an elevation of 1,020 feet is attained. The highest land west of Dayton, 1,000 feet above sea level, occurs west of Drexel park. The highest elevations in the eastern part of Dayton occur immediately north of the “Culebra Cut” on Huffman hill, where a height of 940 feet is reached. Fort McKinley and Oakwood have equally favorable locations, as far as elevation is concerned. [p. 196]
It is evident that as the city fo Dayton expands its growth must be chiefly toward the surrounding hills, since the lower lands already are largely occupied. Within a short time Dayton will become a city of numerous suburbs, demanding water supplies at considerable elevations above the central parts of the community. Then the great quantities of water in the gravels east of Dayton will be of increased importance, and it will be necessary to draw upon the supplies included in the territory beyond the hills east of Harshman. Only the geologist is likely to appreciate the great contribution made by glacial streams to our present and future prosperity by producing such enormous gravel deposits over the preglacial valley bottoms. [p. 197]
[Photo: Gravel pit at southern end of Schumacker ridge. Note the narrow top of the ridge and the steeply sloping sides. On the left side, the horizontal bedding may be detected, even at a distance.] [p. 198]
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