GENERAL OBSERVATIONS ON THE GRAVEL AREAS SOUTH OF DAYTON
[Photo: Natural bridge along road south of David church.]
70. The View From Delco Dell Northward Along the Locust Valley Farm
The view from the Deeds cottage, at the northern end of the Delco Dell grounds, is one of the most charming in the area south of Dayton. Northward extends the flat Locust farm valley, with the western slopes of the Highlands on the east and the southern end of the Eastview ridge on the left. A glimpse of Ridgeleigh Terrace is seen rising above the trees on the crest of the ridge. The Henger homestead lies in the immediate foreground and the Locust farm is seen in mid-distance. On the eastern side of the valley lie the western slopes of the Highlands, consisting of a total thickness of more than 200 feet of sands and gravels, of which only the upper part rises above the valley level. The remainder of this sand and gravel [p. 149]
[Photo: View from the abandoned barn, at the top of the Walden ridge, northeast of the Hole’s Creek bridge, eastward, toward the Schumacker ridge. One of the minor depressions occupying the intermediate valley is seen in the foreground.] [p. 150]
section can be detected only by boring wells, and the total amount of this deposit has not been determined with any degree of accuracy. All of this sand and gravel was deposited by running water, evidently by streams issuing from the melting continental glacial ice sheet, since, in the absence of ice, no streams of any appreciable size could have existed at such altitudes above the neighboring valley country.
Most of the surface of the ground in the Highland area is so irregular that it is not possible to detect the direction of any of the former stream courses. It is probable that the sand and gravel deposits were made by continually shifting streams at different stages of the retreat of the ice front. Many of the lobes of hill land project westward, from the Highland area toward the Locust farm valley, while the subglacial streams on the Moraine farm area, westward, and in the Hills and Dales area, northward, had a southeasterly course. The deposits in the Highlands probably were made immediately in front of the ice margin, rather than in stream channels beneath the ice.
The gravel pit on the hillside northeast of the Locust farmhouse shows the arrangement of the gravels in horizontal layers, due to their deposition by running water. Half a mile northeast of the farmhouse, at the southern margin of the Hills and Dales area, is seen the Hills and Dales Club house, northwest of which the crest of the Adirondack ridge may be traced as far as the woods at Round camp. Beyond this point the woods cover the western slopes of the ridge. This Adirondack ridge marks the channel of one of the streams flowing beneath the ice sheet during its final stage of melting away at the close of the glacial ice age. The buildings of the N. C. R. club can be recognized in the distance. Beyond this point, the Locust farm valley extends northwestward between the Adirondack and Cincinnati pike ridges, connecting with the Miami valley at Carrmonte.
71. The Locust Farm and Kohl Branch Valleys
For the greater part of its length, the Locust farm valley is remarkably flat. At the Delco Dell station its elevation is about 840 feet above sea level, and this is the elevation of its margin for most of the distance north- [p. 151]
[Photo: View from the southern end of the Schumacker ridge southeastward across the Kohl Branch of Hole’s creek, toward the till-covered areas on the hillsides opposite.] [p. 152]
ward as far as the hill land north of the N. C. R. club grounds. Even at the entrance to the lane leading to the Calvary cemetery, at the bend in the Cincinnati pike, the elevation, at the side of the valley, is still as high as 790 feet above sea level. South of the Stroop road, east of the Delco Dell grounds, the Locust farm valley rises within a short distance to an elevation of 980 feet and then becomes remarkably flat again as far as the southern end of the David road, where its altitude is 900 feet. The watershed farther southward, separating the Locust farm valley from that occupied by the Kohl branch of Holes creek, is less than 20 feet higher.
The Kohl branch valley is much more irregular than the Locust farm valley, but it is similar in being bounded on the east by an irregular hillfront, forming a southern extension of the highland area, while on the western side there is evidence of subglacial stream deposits in the form of a gravel ridge extending through the wooded area south of the Van Buren-Miami township line, along the western margin of the Schumacker farm. This Schumacker ridge is well defined only along the southwestern quarter of the farm. Northward, toward the township line, it merges into the more or less irregularly undulating hill land which characterizes the area along this part of the township line.
An eastward continuation of the southern end of the Schumacker ridge would connect it with the hill land along the northeastern part of the Rahn farm. South of this point there is no evidence of the former presence of subglacial streams. At least no well defined gravel ridges are known at present from this territory.
72. The Eastern and Western Boundaries of the Miami Valley in Pre-Glacial Times
In order to secure an approximate idea as to the general appearance of the country before the advent of the glacial ice sheet it is necessary to imagine what the country would look like if all glacial deposits were removed. This implies the removal of all till and kame deposits: in other words, of all clay, gravel, sand, and boulders brought in by the ice sheet or washed along by the streams flowing beneath the ice sheet or issuing [p. 153] from the ice front. This would leave only the original rock layers with such remnants of the covering soil as locally might remain from the days preceding the ice age. As a matter of fact, there is no evidence at hand that any of this former soil still remains in place anywhere beneath the subsequent deposits of glacial material. Moreover, only few exposures of the original rock of this section of the country, in the form of continuous layers of limestone, more or less interbedded with clay, are known within the area south of Dayton here under discussion, although, of course, these continuous layers of limestone must be present everywhere beneath the glacial deposits. The continuous layers of limestone merely are covered up by subsequent glacial deposits.
Limestone layers belonging to the upper part of the Richmond group, and full of fossils, formerly were exposed in road-side quarries where the Cincinnati pike leaves the southern end of Main street. Exposures occurred also at lower levels along the eastern end of the bluffs, almost as far west as the Jewish cemetery. Along the Gutwein property, on the Cincinnati pike, this Richmond rock rises to an elevation of 850 feet above sea level, and originally it occurred at still higher levels in the hills farther southward, in the adjacent parts of Oakwood.
Another exposure of the upper part of the Richmond group of limestones occurs in the southern part of Oakwood, along a northern branch of Meadow brook, where it is crossed by the Houk road, and thence for some distance up stream. Here the exposures, full of fossils, extend from 830 to 875 feet above sea level.
South of Oakwood no exposures of continuous limestone layers are known, for a distance of four and a half miles, until Hole’s creek is reached. Here limestone occurs along the creek where it is crossed by the Mad River pike, about three miles southeast of Alexandersville. This locality is less than a mile south of the hill lands recently acquired by Mr. Deeds and added to ridge properties extending from Moraine farm and Delco Dell southward to Hole’s creek. Here the middle parts of the Richmond group are exposed along Hole’s creek, west of the Mad River pike, as far down as the 780-foot level above sea. Southward from the bridge, up a small branch, the exposures continue to the 820-foot level, and, no doubt, [p. 154] the rock rises to still higher levels beneath the glacial deposits still farther south.
Southwest of Hole’s creek no exposures of bedded limestone are know until the area west of the Springboro pike is reached. Here limestone occurs along two ravines, the best exposures being found about three-fifths of a mile west of the Springboro pike, where a small stream flows northward toward the flat lands surrounding Alexandersville. From this point, as far south as Franklin, exposures are not infrequent along the hill front forming the eastern side of the Miami valley. A magnificent exposure occurs along the railroad track south of Miamisburg, where the Big Four railroad cuts through an angle of the hill. Here the arrangement of limestone in continuous layers, separated more or less by clay, is seen on a large scale. Fossils are common in some of the limestone layers, and some can be washed out in perfect condition from the intervening clay. The exposures belong to the lower and middle parts of the Richmond group.
As far as may be determined from the few exposures cited, the eastern margin of the pre-glacial valley at present occupied by the Miami river formerly extended as far east as a line drawn from the bluffs, east of the Jewish cemetery, southeast through Oakwood to the Lebanon pike. Between the O’Neil and Stroop roads this eastern boundary must have passed east of the pike since the well bored at the Doctor Scheibenzuber residence passed through 180 feet of glacial clay or till without reaching the underlying rock. From this point the eastern margin of the valley probably curved southwestward, more or less parallel to the Mad River pike, as far as Hole’s creek, and then more westward to the hill front south of West Carrollton.
On the western side of the Miami valley, rock exposures are seen along the White line street car tracks east of the Soldiers’ Home. From this point rock exposures are frequent along the hill front southwestward as far as a point a mile south of the Soldiers’ Home, on the Carrollton pike. Exposures occur also along the Narrows, where the hill land borders the Miami river, about a mile and a half northwest of the Moraine station on the Ohio Electric railroad. The locality may be reached readily by the river road following the western back of the Miami river southwest of [p. 155] Dayton. Southwest of this point there are no exposures of rock until the hills west of Miamisburg are reached. It is through this gap between the narrows and Miamisburg that the Miami valley of pre-glacial times may have passed. At any rate, the narrow part of the valley south of Miamisburg, only a little over half a mile in width, scarcely appears an adequate
[Map: Map of Delco Dell, suggesting the former presence of a continuous ridge west of the Delco ridge. This former ridge is now interrupted by gaps. The former continuation of the ridge across the gaps is indicated by dotted lines. Only those cottages and other buildings which were found useful in locating the various gaps and transverse ridges are indicated.]
exit for the wide pre-glacial valley extending from West Carrollton northward beyond Dayton and having a width for a considerable distance of more than two and a half miles.
North of Oakwood, the eastern margin of the pre-glacial valley now occupied by the Miami river is indicated by several outcrops. In regrading the land south of Irving avenue and east of the Schantz park, limestones belonging to the Richmond group were exposed up to a level of 870 feet [p. 156] above sea level. About half a mile southeast of the asylum, east of the Beavertown pike, the Dayton limestone formerly was worked in several quarries between 940 and 950 feet above sea level. Similar quarries existed between half and three-quarters of a mile north of Belmont, and the underlying Richmond strata are exposed in the ravine northeast of Ohmer Park. Richmond limestones are exposed also along the Pennsylvania railroad, south of Huffman hill, and at the northern end of the Huffman hill area, where the traction line to Springfield crosses the railroad track.
73. The Delco Dell Ridges
The charm of the Delco Dell area consists chiefly in the numerous and extensive views across the open country toward the north and northwest. Broad, flat fields, bordered in the distance by steep hill fronts, characterize the landscape. Especially at evening, when the colors of the setting sun illuminate the sky, and the valley plains begin to darken, Delco Dell is a haven of rest. There are times in the day when the views across the eastern valley also are pleasing. To a geologist, however, the chief interest in the Delco Dell area consists in the presence of the steep narrow ridges and included hollows, to which reference has been made so frequently in the preceding pages.
The western or Delco ridge has been used for most of the cottages. Here its ridge character is seen best directly west of the hollow which lies west of the entrance to the Delco Dell grounds. It becomes sill more conspicuous farther southward where it forms the western boundary of Sleepy hollow. The David ridge also is most conspicuous along the Sleepy hollow, of which it forms the eastern border. At the northern end of the Delco Dell grounds these ridges merge.
One of the most interesting hollows enclosed by any of the gravel ridges south of Dayton is the Sleepy hollow, at the southern end of the Delco Dell grounds. Considering its depth and width and the steepness of its walls, it is remarkably large. Its bottom is flat and has accumulated considerable soil, so that the northern half has been used for a long time as a cornfield. This brings up the question, where did the soil come from? [p. 157]
[Photo: Sleepy hollow, in the Delco Dell grounds, looking northeastward across the plowed field in the bottom toward the David ridge, with part of the Delco ridge showing on the left.]
In fact, where did any of the soil on or between the gravel ridges come from?
74. The Origin of Soil
This question of the origin of soil always is a matter of interest. Many factors enter into the formation of a soil and a few of these may be enumerated here in connection with the problem at hand.
In the areas south of those formerly covered by the ice sheet, soil consists chiefly of the finer material left behind by the decay of the country rock. In a limestone country, the soil consists of decayed limestone. In a sandstone country, the soil consists of decayed sandstone. In the process of decay some of the ingredients of the decaying rock may be removed more or less in solution, but, in general, the chemical character of a [p. 158] soil depends upon the chemical constituents of the rock from which it was derived. Soil is produced also by the action of streams. The grinding action of the rocks, pebbles, and sands against each other reduces a part of the material to a fine silt which may be left, at times of freshets, on the neighboring flood plains. In the case of silts, the chemical constituents consist of a mixture of all the materials resulting from the grinding up of all of the rocks represented along the stream channel.
In areas formerly covered by glaciers, soils usually consist chiefly of the material resulting form the grinding up of the rock by the moving ice, or of the sand and silt carried by the glacial streams. It is quite evident that the till or clay included within the lower part of the ice sheet must consist of a mixture of all the rock over which the ice sheet passed, or at least of all the rock with which it came into sufficiently forcible contact to exert a grinding action. Hence, glaciated countries usually present soils rich in all desirable mineral ingredients, and, provided the physical texture of these soils is satisfactory, such soils usually are very fertile. Their physical texture is likely to be best where the clay is more or less mixed with sand, as in the great outwash plains in front of the moraines.
75. The Accumulation of Soil
Frequently several inches of soil cover a gravel hill or plain like a thin mantle. In this case the soil may represent a later deposit than the gravel but frequently it consists merely of the finer particles of clay and sand, originally a part of the underlying gravel, but brought to the surface later by burrowing insects, grubs, earthworms, and other creatures. An ant hill is an excellent example of finer material brought up from below the surface of the soil, frequently from a depth of 6 to 8 inches or even more. The coarser material is left behind and gradually settles into the spaces left behind by the removal of the finer material which has been carried upward.
Most of the soil covering the gravel ridges south of Dayton probably was formed by the method last discussed; it represents the labors of myriads of burrowing animals of all kinds, bringing up the finer particles of clay and sand from among the gravel deposits beneath. Along the tops and sides of the gravel ridges, the clay ingredients often are moderate in [p. 159]
[Photos: Nollman pond, looking north, and Nollman pond, looking south. Note the absence of drainage in either direction. The pond occupies the bottom of one of the hollows between the Pike and Chapel ridges, and is located west of the Nollman house. Part of the water evaporates and part soaks into the gravels beneath. Only during rainy weather is the water supply sufficient to keep it comparatively fresh.]
quantity, so that the covering soils here often are very loose and are readily washed away after the protective covering, consisting of the matted roots of grass and other plants, has been removed.
In the hollows between the gravel ridges the clay ingredients usually are greater. The finer ingredients probably are washed down the sides of the gravel ridges in sufficient quantities during rains to produce thicker soils here. In most of the hollows among the gravel ridges the soil does not contain sufficient clay to hold water readily, so that even after a heavy rain there are no ponds. In a few of the hollows, there is sufficient clay to permit the formation of ponds which usually, however, become dry during the summer. Only a few ponds are known within the gravel ridge area which last practically all year. Two of these ponds formerly existed in the area west of the Cincinnati pike, but at present they become very stagnant or dry up during summer.
When it is realized that these ponds owe their existence to the impervious clay, beneath, holding back ordinary rain water, it will be seen that the quickest way to drain such a pond is to begin to dig in it, in the delusion that underground springs may be opened up. [p. 160]
Along the lower parts of the hollows, the soils often are favorable for cultivation. The northern half of Sleepy hollow, in the Delco Dell area, represents such an area, and the Old Orchard hollow, east of Moraine camp, is another. The sides and tops of the gravel ridges, however, suffer enormously form wash after plowing, and it would be for the best interests of the country if all of this gravel ridge land were removed from the area of cultivation. It will be a continual source of revenue only under two conditions: when covered with grass and used for pasturage, or when covered with trees and used for forestry.
76. The Interrupted Ridge, West of the Delco Ridge
In the Delco Dell area, two ridges stand out prominently among all those present. These are the Delco and David ridges. These ridges are separated by the Delco Dell and Sleepy hollows. The David ridge is steepest and best defined east of the Sleepy hollow. From its crest excellent views are to be had of the territory eastward and of the deep and long hollow westward. At two points, small gravel pits expose the arrangement of the sand and gravel in layers, an evidence that the ridges were formed by the action of running water. The Delco ridge is more interesting on account of the more varied character of the views toward the west. This varied character depends in large part on the presence of a series of short spurs extending westward from the Delco ridge. When these spurs are examined closely it will be seen that they terminate in parts more or less in alignment, as though parts of a formerly conspicuous gravel ridge, at present more or less interrupted by conspicuous gaps. For instance, west of the Kettering cottage, in the Delco Dell grounds, the spur is continued northward as a narrow ridge terminating in the flat fields, while southward it ends within a short distance abruptly at a gravel pit. By the way, in this gravel pit were found limestone pebbles containing fossils indicating that the pebbles consisted of Columbus limestone, probably derived, however, from exposures of this rock on the eastern shore of Lake Huron, in southern Ontario. Map on page 156.
The Chryst cottage stands on the crest of another western spur of the Delco ridge, but at its end it continues northward toward the gravel pit, [p. 161]
[Photo: View of the gap in the frequently interrupted ridge west of the Delco ridge, as seen from a point between the Knopf and Funkhouser cottages. In the gravel pit on the right were found pebbles of Canadian limestone with fossils indicating that this limestone came from the northern extension of the Columbus limestone of Ohio.]
a narrow gap intervening. This gap is seen best from any point of view between the Knopf and Funkhouser cottages. Farther south, the Ruthenburg cottage occupies the crest of another spur, and still farther south, at the southern end of the Big curve in the roadway, a ridge starts off in a southwest direction from the Bachelor’s cottage, and is more or less in line with the end of a spur still farther south. The terminal parts of all of these spurs are sufficiently in line to suggest that they all may once have formed parts of a continuous ridge. This continuous ridge apparently was connected with the Delco ridge by numerous transverse ridges, representing short connecting drainage channels between the main north and south subglacial streams. In this case, the presence of the various gaps, interrupting the supposedly once continuous ridge, require explanation. [p. 162]
Before attempting an explanation for these gaps it may be well to call attention to similar gaps along the hill front extending from the Grand view farm southward toward Hole’s creek. One of these gaps occurs at the eastern margin of the Emrick farm, about a quarter of a mile south of the Van Buren township line, but the most striking example occurs immediately north of this line. Here a deep and narrow valley descends northwestward and then opens through a gap in a more westerly direction into the flat plains beyond. At this gap the valley cuts through a steep ridge, readily followed southward, while northward lies the high ridge land forming the eastern edge of the Sunset ridge, northwest of Moraine camp, include toward the north a somewhat similar gap, but less evidently connected with the former presence of long gravel ridges, later almost entirely removed.
As a possible explanation of the various gaps here mentioned the following explanation is offered as at least possible. It is assumed that formerly the more or less continuous gravel ridges covered a larger territory than at present, expecially immediately west of their present area of distribution. This is suggested by the abrupt termination of a part of the gravel ridgea area west of the Cincinnati pike at its southern end, along the O’Neil road; also by the abrupt beginning of some of the gravel ridges along the various hill fronts south of the Stroop road.
At the time of the melting back of the front of the glacial ice sheet, the melting may have been sufficiently rapid enough to have filled some of the depressions between the gravel ridges and to have causes temporary outflows of the imponded waters, laterally, across the point of lowest elevation presented along the crests of the ridges. These points of outflow later deepened and widened into gaps.
For instance, the watershed between the Locust farm and Kohl branch valleys, northeast and southeast of Delco Dell, at its lowest point is about 910 feet above sea level. See pages 204, 205. If, when the ice front had melted back about as far as the Moraine farm, north of the Stroop road, some part of the ridge then connecting the southern end of the East View ridge with the northern end of the Delco ridge had a lower elevation than 910 feet, an outflow of the imponded waters would have been started at [p. 163] this point of lower elevation and eventually might have led to the formation of the gap along the present Stroop road. At present this gap has been cut down to fully 100 feet below the crest of the highest parts of the ridges immediately north and south.
The highest part of the watershed between the Stroop creek drainage and the waters flowing northward toward the stream crossing the Governor Cox farm does not rise above the 850-foot level. Any waters imponded in the lower part of the Locust farm valley by a glacial ice front,
[Map: Map of Delco Dell and Moraine farm, suggesting that the gap through the ridge area at Stroop road was caused by waters imponded east of the ridges overflowing at a point where the crest of the ridge area was lowest. The former connection of the ridge areas north and south of the gap is indicated by broken lines. The contour lines, 840 and 900 feet above sea level, are shown. Since the gravel ridges are believed to have been formed within a very brief interval of time, the supposed lake can not have been of long duration.]
which had retreated to a point north of the O’Neil road, would have found an exit westward through the Cox farm if any part of the gravel ridge here had at that time a lower elevation than 850 feet. At present, the base of the gap here stands at the 780-foot level, and only the highest part of the gravel hill immediately north of the brook on the Cox farm attains an altitude of 840 feet, so that it is not likely that in glacial times water imponded northeast of the Moraine farm ridges may have found an exit across the northern part of the Cox farm.
Possibly the gap through the Pike ridge, west of the Cincinnati pike, along the Nollman lane, had a similar origin. [p. 164]
It should be noted, however, that no washes of sands and gravels are noted at the outlets of these gaps of sufficient proportions to account for the material supposed to have been removed at these gaps. Possibly some of the meanders of the Miami river, when it skirted the foot of the gravel ridge area along the eastern margin of the Alexandersville flat lands, may account for this lack of corroborative evidence.
[Map: Map of Locust valley area, suggesting that the gap through the ridge area on the Governor Cox farm was caused by waters imponded east of the ridges overflowing at a point where the crest of the ridge area was less than 840 feet above sea level. The gap here was distinctly lower than at the Stroop road. The former connection of the ridge areas across the gap is indicated by broken lines. A part of the land covered by the earlier lake, along the Stroop road, is represented as forming marshy ground. This is merely imaginary.]
77. Differences in the Direction of Trend of the Gravel Ridges in the Area South of Dayton
One of the most interesting features connected with the gravel ridges south of Dayton is their change in direction. For instance, south of the Van Buren township line the general trend of the gravel ridges is about 30 degrees east of south. This trend is seen best along the Schumacker and Walden ridges, southward, and along the western hill margin, where several minor gravel ridges may be detected. An isolated barn stand on the crest of the Walden ridge, in the midst of open fields, and the broad [p. 165] valley between the Schumacker and Walden ridges trends in a similar southeasterly direction, as far as the Rahn road.
North of the Van Buren township line, as far as the cottages in the Delco Dell area, the eastern ridges have a southwesterly trend. Between the Stroop road and the O’Neil road, their trend is approximately 30 degrees east of south. North of the O’Neil road, in the area west of the Cincinnati pike, their trend is almost directly south. In the Hills and Dales area, the trend of the Adirondack ridge is about 45 degrees east of south, while that of the Panorama ridge is almost the same as far south as Fair Forest, beyond which the trend becomes more southerly. Taking the region as a whole, the trends evidently are chiefly southerly and southeastward. The southerly directions are more nearly parallel to the general trend of the Miami valley in the immediate neighborhood, and the southeasterly directions are approximately parallel to the general direction of motion of the ice sheet, as indicated by the glacial striae on the upper surface of the nearest exposures of solid rock
At the Centerville quarry, five miles southeast of the Delco Dell, the direction of these striae is 47 degrees east of south. At the abandoned limestone quarries west of Beavertown, three miles northeast of Delco Dell, their direction is 27 degrees east of south. Half a mile south of the Soldiers’ Home grounds, their direction is 35 degrees east of south. From this it may be seen that those gravel ridges which have a more southeasterly course have a trend approximately parallel to the former direction of motion of the glacial ice sheet, at least during the closing stages of motion of the ice, at the time of retreat of the ice front. However, it is chiefly during this time of retreat, when the ice was most stagnant, that the gravel ridges are believed to have been formed.
78. The Termination of the Southern End of Some Gravel Ridges Against High Land
The gravel ridges are regarded as deposits formed by streams running in channels beneath the ice sheet. There are two features connected with these gravel ridges which demand explanation: one of these is the termination of some of these ridges southward against an area of high land, and [p. 166]
[Photo: The gap through the gravel ridge at the Governor Cox farm. The northern end of the Ridge on the southern side of the gap is used as a gravel pit. The culvert along the Cincinnati pike, crossing the stream, is seen north of the house. The high hill on the left side of the view is supposed to have been connected formerly with the ridge on the right.]
the other is the presence of several ridges in the same area extending approximately parallel to each other for long distances.
The first feature is well represented by the Adirondack and Panorama ridges, which trend southeastward and terminate in the high hill area in the southeastern part of the hills and dales. In a similar manner, the Grand View farm and Delco Dell ridges terminate southward in a high area extending along the Van Buren-Washington township lines. It is probable that the Walden and Schumacker ridges formerly extended southeastward across the present Rahn valley and connected with the high land southeastward. All of these occurrences suggest that the subglacial streams toward their points of exit from beneath the glacial ice built up their deposits [p. 167]
[Photo: View of the western sides of the Chapel and Pike ridges, taken from the northwest. The house in the immediate foreground is the home of Mr. Sauerman.]
until the bottoms of the stream channels rose to near the present level of the adjacent hill country. The high land would act as a barrier, checking the violence of the stream flow and favoring rapid deposition, until the stream bed was lifted to about the same level as the hill land.
In fact, it is probable that the gravel ridges were formed within a very short interval of time. It seems scarcely likely that even subglacial streams would long continue to flow on tops of steeply inclined gravel deposits, when by melting the bordering ice walls they could descend to lower levels. The higher and steeper the gravel ridge, the more likely it is to have been formed within a short period of time.
79. The Presence of Parallel Ridges Within the Same Areas
It is possible that the parallelism among the various gravel ridges may be due to large crevices produced by shearing in the glacial ice. It may be noted that the direction of motion of the glacial ice near the closing [p. 168] stages of the last glacial invasion, was approximately 30 degrees east of south in the area here under discussion, while the hill front along the Lebanon pike, against which the ice was thrust, had a direction approximately north and south. Hence there would be a tendency for the ice to be held back at relatively more northern points along the hill front, and to move ahead along relatively more southern points. This should produce shearing planes parallel approximately to the direction of motion of the ice. The more prominent of these shearing planes might develop, under the influence of glacial waters, into crevices of sufficient size to permit the flow of fairly large-sized streams.
This widening of shearing planes into wide subglacial channels would be favored by a nearly stagnant condition of the ice sheet. An ice sheet moving forward with any degree of speed would tend to close up any crevices existing in the ice, so that if shearing planes should develop into crevices, these crevices would be likely to remain open only for short periods of time.
80. Changes in Direction of the Gravel Ridges Probably Caused by Changes in Direction of Flow of the Ice During Its Various Stages of Retreat
Different groups of gravel ridges may have formed at different times. For instance, the southeasterly trending ridges extending from the southern margin of Van Buren township to the hill land south of the Rahn valley may be among those earliest formed. Their direction is well defined only along their southern terminations. As the ice front melted back, the more southerly directed ridges in the Delco Dell area and on the Grand View farm may have been added, possibly during a more stagnant condition of the ice. Next, the more southeasterly directed ridges between the Moraine farm and the O’Neil road may have been formed, and finally the numerous more southerly directed ridges west of the Cincinnati pike may have been built up. The Adirondack and Panorama ridges, in the Hills and Dales area, may have been more or less contemporaneous in origin with the ridges between the Moraine farm and the O’Neil road. [p. 169]
[Photo: View of stream east of Carrmonte, looking east toward the high ground in Oakwood. Note the ox-bow bends, and the effect of the wandering of the stream in producing more or less flattened territory. Something similar to this may have happened on a much larger scale in case of the Miami river valley. The deepest part of the channel in the immediate foreground is on the left, where the stream is cutting into the hillside, on the convex side of the curvature. On the concave side of this channel the gravel washed along by the stream from points farther up its course is deposited. Photographed in 1895, during a time when the stream had dried up.]
In that case, it is possible to regard the confused area of hill land extending for fully a third of a mile north and for nearly the same distance south of the Van Buren-Washington township like as due to the over-riding of glacial ice, with southerly directed stream channels, over a territory already covered with southeasterly directed gravel deposits or gravel ridges. Apparently the ice front stood at this point long enough to permit of a thicker and more widely distributed series of deposits than elsewhere in this immediate neighborhood. Hence the Van Buren-Washington township line marks the position of the watershed between the Locust Farm valley northward and the Schumacker farm valley southward.
This explanation regards the change in direction of the gravel ridges as connected with successive stages in the retreat of the ice front. It is not impossible, however, that the entire series of crevices over its total length of four and a half miles, may have been in existence at the same time so that all the deposits along the line of the present gravel ridges were going on [p.170] simultaneously. There is no reason for believing that shearing could not produce a series of southeasterly directed crevices and of more southerly directed crevices in the same general area at the same time.
Only in case the deposits were made within a very short interval of time, however, could numerous approximately parallel subglacial channels be expected within the same area. Given, however, an abundance of rock and sand, the accumulations of many years of transportation by glacial ice, and a sufficiently rapid flow of an abundance of water, and all of the gravel ridges south of Dayton could be built up in a very short time.
These gravel ridges are not moraines in the sense that they have been deposited directly by the glacial ice, but they unquestionably consist to a large extent of actual morainal material reworked by running subglacial waters at the immediately ice front. In that sense of the term, these gravel ridges mark the terminal moraine area of one of the stages of retreat of the Wisconsin ice sheet. In other words, they form a local feature of the Germantown division of the Dayton moraine.
81. The Western Gravel Ridges in the Area Between Delco Dell and Hole’s Creek
The two most conspicuous gravel ridges in the southern part of the area north of Hole’s creek are the Schumacker and Walden ridges. The Schumacker ridge is wooded, but most of the Walden ridge is fully exposed in the open fields. A deep broad valley separates these ridges southward, but northward, along the high ground, the ridges are only indistinctly defined. The Schumacker ridge may be traced as far as the eastern side of the gully on the old Eby farm, directly north of the line between Van Buren and Washington townships. A parallel and much more conspicuous ridge forms the western side of this gully and is interrupted by a gap near the northeastern corner of the Emerick farm. The gap may be reached readily by following the Delco ridge southward through the woods as far as the open fields and then crossing the latter straight westward to the high ridge forming the western boundary of the high gravel area. The gap is located a short distance north of the farm road crossing this ridge. [p. 171]
Near the old abandoned barn on the top of the Walden ridge the latter divides into two branches southward. Northward this ridge may be traced to the big gap east of the farmhouses on the Emrick farm. Here it forms the high land along the fence forming the eastern boundary of the farm. See pages 204, 205.
The Emrick ridge, farther westward, extends from the Emrick farm houses southeastward in a direction parallel to the Walden ridge. It is an excellent illustration of an interrupted ridge, but on a much larger scale than the interrupted ridge in the western part of the Delco Dell grounds. It is intersected by numerous gaps and in the area directly west of the old
[Photo: The southern end of the kame area west of the Cincinnati pike, as seen from the Ohio Electric railroad southwest of the Governor Cox farm. The most eastern hill, on the right, is the southern end of the Pike ridge, at the sub-power station. View taken across the flat lands of the Miami. The southern end of these more western ridges appears to have been cut off by a Former ox-bow bend of the Miami river.]
abandoned barn on the Walden ridge it is intersected by the conspicuous washed gully which is one of the best illustrations of the danger of removing the protective covering of grass and shrubs from a steep hill side. This washed gully lies south of the road leading northeastward up the hill-side from the Walden homestead. West of the southern end of this interrupted Emrick ridge several additional small gravel ridges may be seen. All of these ridges have a southeasterly and approximately parallel direction. While much less sharply defined, as a rule, than the ridges farther northward, especially those west of the Cincinnati pike, they evidently had the same origin, and prove the former presence here of subglacial streams. [p. 172]
82. The Ox-Bow Bends of the Miami River
One of the most conspicuous ox-bow bends of the Miami river is presented by the old river channel north of the bluffs between Oakwood and the western margin of the Calvary cemetery. It is probable that the gravel ridges west of the Cincinnati pike once extended farther northward, into the broad Miami valley, but in that case the northern ends of these ridges evidently were removed by the wash of the river.
Possibly the abrupt termination of the more western gravel ridges, west of the Cincinnati pike, north of the O’Neil road, may have been due to a similar ox-bow bend truncated not only the southern ends of the more western gravel ridges north of the O’Neil road, but also the northern ends of the ridges on the Grand View farm. It can not be said that the evidence of such a former ox-bow bend in the Miami river is at all clear, but its presence is suggested by the general contour of the western margin of the gravel ridge area, where it adjoins the flat bottom lands of the Miami valley.
Evidently the Miami river has been a great traveler. Northwest of Oakwood it carved out a path considerably toward the east of a direct channel and at the Pinnacles it follows a path considerably west of a direct line. Evidently these ox-bows are of much more recent date than the hypothetical one south of the O’Neil road. [p. 173] [p. 174]
Return to "Geology of Dayton and Vicinity" Home Page