Engineering Significance of Sand Areas' Interpreted from Airphotos

28 state occur in most tropical countries. onable assurance of safety. Figures 13 and 14 illustrate these in Puerto On the good side of the record, it is Rico. Each landform has its strength and certain that most limestones furnish one weaknesses, and hy identifying the land- of the best and most extensively used form and knowing its traits, a better job aggregates. With the exception of the of engineering can be done. In this way, very cherty limestones, it forms a de• the risk can be calculated with some reas• pendable and high quality material.

ENGINEERING SIGNIFICANCE OF SAND AREAS' INTERPRETED FROM AIRPHOTOS

A. Morgan Johnson, HiD, 4ssociate Professor of Civil Engineering Ylayne University

The investigation summarized here was ment, drainage characteristics, texture, established as a doctoral thesis in the in• plasticity, and topography. In the in• terpretation of soils by the use of aerial terests of economy it is necessary to de• photographs, the interpretation to include velop rapid means of identification of both engineering mapping and analysis of soil types and of characteristics. Until highway problems associated with the types the recent advent of the techniques of air• of soils classified. It was attempted to photo soils interpretation, no rapid method interpret the complex patterns of the air- of soils mapping had been developed. To photos of northwest Indiana--patterns which the skilled interpreter, the aerial photo• have been made ccoiplex by the large variety graph, combined with a knowledge of the of glacial and post-glacial deposits which general development of the area being have provided the parent material for the studied and of some of the basic concepts developments of the soils of the region. of pedology, as well as a familiarity with All or portions of twelve counties were methods of soils engineering, is a rapid mapped, using airphotos, in the belief that method of obtaining knowledge of the engi• a good knowledge of the soil types of an neering characteristics of the soils of area is the basis of good highway design an area. in that area. Consequently, the area was The basic techniques of airphoto inter• studied both from the standpoint of de• pretation of soils have been described in veloping techniques of mapping engineering the past (1,2). They include acquaintance soils from aerial photographs and from the with geological developments and processes standpoint of determining applications of in the area being studied and with pedo- the knowledge of the mapped soils to prob• logical information as to profile develop• lems of highway design and construction. ment, erosion, and vegetative cover. Study Studies of pavement performance were made of broad areas is combined with stereos• during the spring breakup and during the copic examination of matching prints to sumner season to correlate soil types with determine the details of the surface feat• the performance of both rigid and flexible ures, llie elements of the airphoto pattern pavements. (color tones, drainage, erosion, vegeta• Before the variable of soil texture can tion, topography, and land use) are uaei be applied to the performance of a hi^way, to bound soil areas on the basis of origin, it is necessary to know what the soils in• developoient, texture, topographic position, volved are—their origin, profile develop• climate, drainage and plasticity. An im- 29 portant factor used in airphoto mapping is many areas. Many of these have been re• the concept that any given pattern will be ported in part and some have established changed if other deposits are accumulated strong correlation between soil types and on top of the soil of that pattern. The pavement performance (3,4,5). "Iliere are amount of modification depends upon the many factors which may affect the perfor• amount and nature of the overburden. The mance of a particular section of concrete complex patterns of northwest Indiana pavement; coarse aggregate, fine aggregate, proved to be modifications of the more mix design, construction procedures, joint standard patterns and could be worked out design, subgrade, base, drainage, and by a process of reasoning following careful others. A similar list of factors can be observation of the elements of the patterns. developed in regard to flexible pavements. Consequently, isolating one of these fac• Many states have realized that in their tors and successfully correlating it with highway system they have an extensive field pavement performance is not a simple task, research laboratory, and large-scale per• but it has been handled with apparent suc• formance surveys have been undertaken in cess in at least some areas.

LAKE STATE OF MICHIGAN

MICHIGAN

OSEPH CALUMET LAPORTE LACUSTRINE s STEUBEN LAKE PORTER MORAlNAi:I ^ AKEISECTION

ftJlK STARKE ARSHALC®

PULASKI JASPER NEWTON

WHITE

BENTON TIPTON CARROL

TILL PLAIN

Figure 1. Physiographic Divisions and Federal Highways in Northwest Indiana 30

as*!

rULTOM CO

Figure 2. Typical County Engineering Soils Map. This soils map is of Starke County in Indiana in the Kankakee basin. It is typical of the several counties which have the Kankakee River for their northern boundary. The soils are largely of lakebed development except for a small area of outwash gravels in the northeast corner and an area of semi-plastic drift in the southeast por• tion of the county. Eight soils were mapped m this county and the detail is representative of that which can be obtained from airphotos.

AREA AND ME1HGD6 been covered once or more by the glaciers and their heterogeneous deposits of drift. Seventeen counties in northwest Indiana The northern part of the state lies within were surveyed in order to map the sand the bounds of the last great advance of the areas described in this report. TTiey fall glaciers—Late Wisconsin--so that the soils within the region known physiographically and topography of that part of the state as the Northern Moraine and Lake Section, are almost wholly controlled by the glacial a region bounded on the south by the Tipton deposits and some subsequent development. Till Plain. Three of the divisions of the In the Valparaiso Moraine section and the section are involved in the area studied, Steuben Morainal Lake section the surface illustrated in Figure 1. These are the deposits are those of the glaciers--the Calumet Lacustrine section, the Valparaiso Valparaiso Moraine being the most promi• Moraine section, and the Kankakee Lacus• nent terminal moraine of the Michigan lobe trine section. "Die Steuben Morainal Lake of the glacier and the deposits in the section borders the area studied on the Steuben area being those of the Erie and east. The major portion of Indiana has Saginaw lobes. Hie rolling hills of the 31

terminal moraine are the predominant feat• ures of the topography in these areas. Actual till plains are rather rare in this section of Indiana. In the Lacustrine sections, the deposits are those which were laid down by running or impounded waters during and following the time of the gla• ciers. The entire region is so comparatively young that with the possible exception of sand dune formation there have been no great natural changes in topography since the respective deposits were laid down. Drainage developments and erosion have been relatively scant. Other surface changes have been wrought by the efforts of man in the past hundred years. Hiese are vegeta• tion, construction of highways and rail• roads, and artificial drainage of many of the swampy areas. The Calumet Lacustrine section is the former lakebed of glacial Lake Chicago—an extension of Lake Michigan --and is marked by several prominent beach ridges, plastic and sandy lacustrine de• posits, swamps, and the more recently de•

veloped prominent dunes bordering Lake Figure 3. Airphoto of Large Flat Areas of Michigan. The Kankakee Lacustrine section Sands. This pattern of flat-lying sands in embraces a large area lying south of the Jasper County, Indiana, has been modified Valparaiso Moraine. It centers about the by wind-swept sands, both active and sta• Kankakee River which at one time carried bilized. The white spots are currently vast quantities of glacial waters and when shifting sands whereas the patches of trees dammed up to the west in Illinois, impounded mark dunes which have become stable. The water over a large area, giving rise to the main area shows the very flat topography deep sand deposits which cover much of the and uniform light-gray color tones of the basin. Extensive areas of outwash materials flat sand areas. There is almost complete occur about the borders of the basin and to lack of natural surface drainage but the the north and east. Artificial drainage has area has been ditched to lower the water lowered the water table in most of the table. sandy basin reclaiming a vast swamp for productive pursuits and drying the surface a particularly fruitful one for performance sands to the extent that many active dunes studies. have been and are being formed. Mapping was conveniently done in units Many prominent federal highways from the of counties. A mosaic of the prints of Chicago area fall within the area studied the county was assembled on a board and and other important east-west and north- studied. After a preliminary understanding south highways were available for perfor• of the area and its soils had been developed mance studies as well as many state high• and after preliminary approximate bound• ways and surfaced roads of lesser impor• aries had been lightly marked on the prints tance. The US highways crossing the area where it seemed possible to make an early are also shown in Figure 1 and include US prediction, the prints were examined ster- 6, 12, 20, 24, 30, 31, 33, 35, and 41. eoscopically in considerable detail. When These heavily traveled roads, traversing it had been ascertained what boundaries many different soil areas, made this area could be marked with strong assurance and 32 which boundaries were somewhat questionable, SOIL AREAS AND THEIR INTERPRETATICK^ a field trip was planned. Field checks of soil types were made and samples taken to Large Flat Areas of Sand - lliese were laid check textural composition and Atterburg down as lakebed deposits at the time when limits. After the additional information the Kankakee River was dainned and perhaps of the field work was available, the mark• ing of the boundaries was completed on the have been reworked during lower stages of airphotos and the markings transferred to of the lake. Topographically, they are a base map of the county by means of a monotonously flat. During the time of transfer table. Figure 2 is an illustra• Kankakee Lake, numerous beaches and islands tion of a typical county soils map. were formed and modified so that many long• standing mounds and ridges are scattered Soils areas as marked were combined into throughout the area. Later wind action broad groupings, such as are described later has further modified these hills so that in this report, on the basis of features they have the appearance of and are com• and characteristics identifiable from the monly referred to as dunes. "Diese may oc• airphotos. fti the basis of previous ex• cur at random in the flat sand areas or in perience in correlation of pavement perfor• close groupings over large areas, in which mance with soil types, it was then possible latter case they were mapped separately on to predict the type of highway problems to the strength of topography, position, and be encountered in the areas mapped. Spring drainage. The surface deposits in the flat breakup studies of flexible pavements and areas are fairly uniform in size and tend condition surveys of rigid pavements served toward one-size sands, although silt may to substantiate these predictions. occur in the topsoil. In many cases the)

SIEVE NO. 200 100 40 20. 100

60 O GRAIN SIZE CURVES z representative sand to samples tn < PULASKI COUNTY a. 40 DUNE SANDS - BEACH SANDS

WHITE COUNTY DUNE SANDS BEACH SANDS. 20 LAKE MICHIGAN DUNE SANDS LAKE CHICAGO —7-". BEAChL SANDS 05 0.1 02 0.5 1.0 2.0 5.0 GRAIN DIA. mm

Figure 4. Grain Sue Curves of Dune and Beach Sands 33

Figure 5. Airphoto of Sand Dune and Ridge Area. This stereogram is very rep• resentative of the sand dune areas in the Kankakee basin. It covers a portion of a band of dunes two or three miles wide extending across the flats. In the lower left corner of the picture may be seen the change to the flat areas of sands. 34

are underlain by coarser sands and gravels. There are some faint indications of slow- They drain well when the water table is low flowing water to be seen in the area but enough and artificial drainage has accomp• these are probably due to a former con• lished this in most of the area. dition at the time of draining. These areas are marked by rather uni• In regions where artificial drainage form light-gray color tones (Fig. 3). The has lowered the water table, these soils topography is very flat and the field pat• generally provide excellent subgrades. tern is rectangular. Wind whipping across There are many miles of excellently per• the surface has picked up sand and de• forming flexible and some rigid pavements posited it in small dunes, indicated by on sands of this type. In general the white spots on the photo. Dunes which have traffic on these roads is not heavy. Under reached a state of equilibrium and have heavy loads, faulting might he appreciable. retained their shape for some time are Location is no problem because of the flat• marked by native trees, usually oaks. There ness of the area and no cuts, with their is an almost complete absence of natural changes in profile, need be considered. surface drainage and at least one ditch may The area contains many small regions where be found in every square mile of the area. the top soil is very highly organic and this soil presents a problem in location. If these small regions, easily identified on the airphotos, cannot be avoided, it is desirable to excavate the organic material and back-fill with clean sand. No other granular materials are likely to be avail• able in the iimiediate vicinity.

Sand Dunes and Ridges - There are extensive areas of this soil type lying south of the Kankakee River and another broad belt of dunes surrounding the south and west shores of Lake Michigan. Their most characteris• tic feature is the topographic expression of sands in the dunes and ridges. The dunes appear in modifications of the cres• cent shape, as long ridges, and occasion• ally as mounds. An effort was made to de• termine whether the ridges might not be of water-laid origin rather than wind-blown. Many comparative samples were taken from wind-blown tops of ridges and from deeper down where it was expected the sands may have been water-laid. The plot of the grain-size distribution curves (Fig. 4) showed no significant difference in the Figure 6. Airphoto of Sandy Outwash. The grain sizes at the two locations. To de• major portion of this photo is of the sandy termine whether a difference in grain size outwash area in northwestern St. Joseph of wind-blown and water-laid sands might County in Indiana. It shows gently rolling be expected, similar samples were taken to flat topography and light-gray color from the large dunes along Lake Michigan tones. Infiltration basins are faint and and from deep in the beach ridges of Lake there are no gullies. The left portion of Chicago. The data were compared and it the picture bounded by the dashed line, was concluded that the beach sands and the shows the contrast of the more granular dune sands were of essentially the same pattern. Figure 7 is illustrative of the size. This conclusion is reasonable be• topographic change at this boundary. cause all the sands are from the same source. 35

Figure 7. Ground Photo of transition From Sandy Outwash to Gravel Outwash. This photo, taken along SR No. 2 in Eastern St. Joseph County, shows the sharp change in topography at the border between the sandy outwash area and the gravelly outwash marked in Figure 6. The hill to the left rises over 100 ft. above the level of the adjacent plain--an extreme local change in elevation for these types of materials. •

although it might be expected that water state, which will also cause some modifi• action could wash up larger particles and cation of cut and fill slopes. Tbis process that wind deposition would be more select• is slow, however, and the slopes are usually ive. It was also noted that there was a left bare on secondary roads. Rounding the striking uniformity in size between the slopes, bringing in top soil, and develop• sands surrounding Lake Michigan and those ing a sod cover or planting special grasses in the Kankakee basin. are practiced on some primary roads. The This soil type is one of the easiest to sands are stable when confined but are recognize on the airphotos as the shape and likely to rut in a natural surface because topography of the dunes, the light color of lack of binder. The same is true of tones, the blowouts, the absence of gully• these sands under very thin surface treat• ing and surface run-off, and the patches of ments. To be entirely satisfactory, the trees can hardly be mistaken (Fig. 5). subgrade should be stabilized or the pave• Aijother strong feature of the area marked ment should have some structural strength. in the airphoto pattern is the large number It has been shown that bituminous materials of muck pockets found in some portions of and other additives may aid in such sta• the area. The field pattern is likely to bilization. Sands also present a problem be irregular and ditches are frequently in compaction because of their uniform size. used to lower the water table in the muck- They are subject to vibratory compaction filled depressions. and consequently are prone to compact under Location of highways in this area is the action of traffic and cause settling largely a problem of avoiding the muck and faulting of the pavement. It is this pockets. Cuts are required through the type of action that has led to faulting on dunes and ridges but the sands are deep many rigid pavements placed on a 4 or 6- and no change in texture is involved. A in. insulating blanket of sand. In some definite problem with these sands is the instances the sands may be mechanically matter of stabilization. The sands are stabilized by bringing in fine material. subject to wind erosion in the natural The excellent drainage characteristics of Figure 8. Airphotos of Sands and Gravels. These three pictures illustrate the salient pattern features of sand and gravel outwash materials: Current scars, infiltration basins, muck channels, rectangular field patterns, gently rolling topography, and few short gullies. The picture on the left is of an area in Fulton County, just east of Lake Manitou in an outwash channel leading to the Tippecanoe River. The center illustration is of the outwash from the Valparaiso Moraine in eastern Laporte County! and the photo on the right is of the outwash pattern in northern St. Joseph County. All three photos are to the same scale.

the sand may require that water-proof paper sand dunes are much less in evidence. The be laid on the subgrade before concrete is texture of the surface sands does not fall poured to halt the draining of the water within such narrow bands as that of the from the mix into the subgrade. sands previously described and the under• lying material, frequently gravel, may Sandy Outwash - Northern Indiana has many occur at shallow or considerable depths. areas of sandy outwash formed during the The topography may be gently rolling and time of the Late Wisconsin glacier by break• there is little surface drainage. The throughs or over-flows of the moraines by granular nature of the soil and the under• waters impounded by rapid melting of the lying gravel is such as to give excellent glacial front. The surface and topography internal drainage, but artificial drainage is quite similar to the area mapped as has been practiced to lower the usually large flat areas of deep sands except that high water table. 37

There is often marked contrast in the performance may be expected in general in airphoto pattern between soils of this these soils although some faulting may oc• cur at slab joints under heavy traffic. group and the adjacent sand and gravel Muck pockets should be avoided but an abun• areas, as seen in Figure 6. Hie topographic dance of granular materials is available for fills and other construction. Slight contrast is also well-marked (Fig. 7). The evidences of pumping have been observed in color tones of the airphoto of sandy out- cuts in this area, but samples of the sub- wash are quite uniform gray. Hiere are no grade soil from the locations involved showed no measurable plastic or liquid gullies in evidence although faint infil• limits and had but 3 to 15 percent of the tration basins and current scars may be total sample finer than the No. 200 sieve. seen. The field pattern is rectangular. The highway problem of major consequence in this area is that of drainage, for un• less the area has been ditched the free- water surface may be too near the surface Plastic and Semiplastic Drift - Although to allow stable suhgrade conditions. Fault• the terminal and ground moraines of the ing also may occur. Wisconsin drift sheet are not included in

Sands and Gravels - Large areas in northern Indiana were mapped as sands and gravels consisting largely of outwash deposits along glacial streams and from water im• pounded behind moraines. Soil profiles in this area usually show 6 to-18 in. of sand, including some topsoil, over a foot or two of gravel containing varying amounts of sand, silt, and clay. Since the materials were water-laid they are stratified, and layers of sands and gravels may be encoun• tered to an appreciable depth. The topo• graphy varies from undulating to strongly rolling. Surface drainage is not strongly developed as the drainage is largely in• ternal. Muck channels may be fairly numerous. The feature of the airphoto pattern is the mottled and pitted appearance typical of coarse, granular materials. Although the surface drainage is slight there are short V-shaped gullies and many current scars and infiltration basins. Color tones 1 are predominantly light to light gray but many dark muck pockets and channels are likely to develop. The field pattern is Figure 9. Airphoto of Plastic Drift. This usually rectangular, and orchards are fre• airphoto, covering an area just south of quently visible on the photos. The simi• US 24 in southern Jasper County, Indiana, larities among the patterns from widely is representative of the pattern of large scattered locations may be observed in the areas of Wisconsin drift till plains. It photos in Figure 8. shows absence of intense erosion, abun• These materials are among the best of dance of phantom drainage as indicated by the subgrade soils. They are well drained the arrows, gently blended light and dark and stable. In some areas the topography color tones, and rectangufie1d which are is sufficiently rugged to cause fairly features usually found in airphotos of steep grades and rather deep cuts. Excellent this soil type. 38 the "sands" discussed here, it is necessary topography somewhat less regular than the to describe them in order for them to be plastic till. Its profile development is used as background for the airphoto inter• similar to that of the plastic drift al• pretation of shallow sands on drift as well though the B and C horizons are somewhat as for description of the engineering more granular. The parent material con• characteristics of the shallow sands. Map• tains sufficient sand and gravel to provide ped as plastic drift are the ground mo• some permeability. raines, occurring in the area, many of the The airphoto pattern of plastic drift terminal and marginal moraines, and areas as seen in Figure 9 exhibits an absence of of waterworked drift. The P horizon of intense erosion, and in the non-morainic these soils may be a combination of plastic areas ditching has been necessary to pro• clays and silts with sands while the parent vide some drainage. The patchy light and material is a somewhat heterogeneous mass dark areas, gently merging, are a develop• of clays, silts, and pebbles. The soil is ment of the drainage conditions, the dark relatively impermeable and has flat to areas being the depressions and the lighter gently rolling topography except in the areas the relative rises. There is an morainic areas where it is somewhat rough• abundance of phantom drainage because of er. The semiplastic moraines exhibit the impervious nature of the subsoil. Rec-

Figure 11. Airphoto of Granular Drift.

P'igure 10. Airphoto of Semiplastic Drift. Representative of the granular drift of the This photo is of an area in southern Fulton Maxinkuckee Moraine in northern Fulton County mapped as semiplastic drift. By County, this photo is of an area along US contrast with the pattern of plastic drift, 31. It exhibits the typical features of illustrated in Figure 9, it shows more the pattern of this type of area: Abun• irregular slopes, some eroded slopes, a more dance of steep slopes and freshly eroded definite transition from light to dark slopes with V-shaped striated gullies (a) color tones, and a somewhat more developed There are muck pockets and an abundance of drainage but with some infiltration basins infiltration basins (b) and light color as indicated by the arrows. tones predominate. 39

tangular field patterns are characteristic development of the B horizon so that this of a plastic soil. The pattern of the horizon is more shallow than in the more semigranular areas (Fig. 10) is inter• plastic drift soils and it tends to be pre• mediate between the plastic drift as des• dominantly silty. cribed and granular drift. The slopes are The steepness of the slopes is accom• more irregular than in plastic drift; there panied by relatively greater depressions are some evidences of phantom drainage and and the development of muck areas is more also some fresh gullies; the color transi• prevalent in this type of drift. Except tion from li^t to dark is more pronounced; in the muck areas, light color tones pre• and there may be some infiltration basins. dominate, but they are interspersed with The major problem in the plastic drift many infiltration basins, indicating the area is that of cuts into the plastic B granular nature of the parent material. horizon and parent material. Due to the The slopes are more freshly eroded and gently rolling nature of the topography, gullies are nore numerous than in plastic there is a tendency in design to cut in or semiplastic drifts. The gullies fre• the rises and fill in the depressions. The quently have a striated appearance and have fill in the depressions is advantageous for it provides an elevated grade line in an area where drainage is poor. However, further elevation of the grade line is de• sirable to avoid cuts. Performance of pave• ments in cuts, particularly where the grade crosses changes in profile, is generally rather poor. Tlie impervious nature of the soil makes drainage a problem in these areas. Rigid pavements will frequently develop pumping in these cuts. Frost heaves are also frequent occurrences in cut sec• tions and spring breakups of flexible pave• ments are prevalent in the cut sections during the season. If the grade line can• not be sufficiently elevated and cuts prove to be necessary, a blanket layer of granu• lar material is recommended. Problems in the semiplastic areas are not unlike those just described; although the texture of the soils is less plastic, it is still sufficiently poor to cause poor pavement performance in cuts. Tlie rougher nature of the topography makes elimination of cuts unlikely so that the blanket course in cuts is desired in construction. Drainage meas• ures need also be taken. Figure 12. Airphoto of Sand (3 to 5 feet deep) Area. This area in central Jasper GranuZar Drift - These deposits are more County occurs on the northern slopes of the likely to have been left as terminal or Marseilles Moraine where the sands of the edge moraines than as ground moraines. Kankakee basin have been carried up over TTiey exhibit a rougher topography than the the drift. It is marked by smooth slopes more plastic forms of drift. The parent with some dunes which are usually covered material is granular and contains large by native trees. Three of these dunes are percentages of sand and gravel, as well as outlined on the photo. There is little some silt and clay. It is often character• evidence of surface runoff and the light ized as "dirty gravel." The comparative and gray color tones take the pattern of steepness of the slopes has retarded the the underlying drift. 40 I . fairly steep sides. Many of these fea• grade reasonably well drained. The ma• tures will be noted in Figure 11. Ditching terials are sufficiently graded to provide is not necessary to secure drainage for excellent borrow material and can be used these soils. as surfacing for county roads. Poor per• The major problem of this area is prob• formance is not to be expected except un• ably that of location. The topography is der adverse conditions of traffic and relatively rough and the slopes are suf• climate. The problem of surface erosion ficiently steep to introduce the need for is one which should be considered, and pro• moderately deep cuts and correspondingly tection is needed for cut and embankment higl] fills. Another factor in the location slopes to retard eroding. problem is the occurrence of muck pockets in the area. However, the problem of cuts and Sands on Drift - These sands were included fills is not a difficult one because of the as an intermediate group between the shal• granular nature of the soils. They provide low sands, which were mapped as 3 ft. or excellent embankment material and drain less in depth, and the deep sands, which well, even in cuts. Gutters of moderate included those 5 ft. deep and more. In depth in deep cuts should keep the sub- sands of this intermediate depth the char• acter of the underlying drift has some in• fluence on the airphoto pattern as well as on the highway problems involved, but it did not appear feasible to attempt to dif- fentiate between the different types of underlying drift on the basis of the air• photo pattern. Field sampling showed sands of this depth lying on plastic, semiplastic and granular drift. The superficial fea• tures of this area are those of the deep sands as discussed earlier. The sands are either water-laid or wind-blown and gen• erally are one-size^) in texture although the water-deposited sands m.ay include larger grains. Figure 12 shows that the color tones of this soil pattern are light and gray, oc• curring in a pattern similar to that of the underlying drift. However, the character• istic mottling shows through in a modified form and the surface is further modified by sand dunes and ridges. The slopes are generally smooth and there is a certain amount of phantom drainage. Surface runoff is generally lacking. As is characteristic 1 of sand dunes, they may be covered with oak

Figure 13. Airphoto of Shallow Sands on trees when they are sufficiently roug^ and Plastic Drift. This area occurs in central have so little topsoil development that Newton County in Indiana on the northern they are not tillable. Depth of sand in slopes of the Marseilles Moraine, but un• the dunes may, of course, be over 5 ft. but like the similar location in Jasper County on a small scale map it was not reasonable (Fig. 12) these sands average less than 3 to map such isolated spots. ft. in depth. This photo exhibits most of The highway problems of this soil area the features of the airphoto pattern of are not dissimilar to those of the areas plastic drift, including phantom drainage. of more shallow sands, except that the Color tones are very light on the elevated problems can be expected to occur with less areas and gray in the depressions. frequency. The sands are of sufficient 41

depth that they provide a good subgrade in through the shallow sand and into the under• spite of the character of the underlying lying drift may be expected frequently. Tlie zone of intersection of the sand and drift, unless cuts penetrate too deeply. drift boundary is likely to show evidences Consequently, only in the deeper cuts need of poor performance. The combination of we be concerned with poor subgrade con• sharp change in soil texture combined with the plastic and impervious nature of the ditions. The topography will be affected drift makes this soil area one of the worst by that of the underlying drift. If the mapped from the standpoint of highway prob• drift is granular there is the problem of lems. The usual problems of silty clays will be encountered in the regions of cut location to avoid deep cuts and fills and where the pavement is laid on the drift. to avoid muck pockets. In the more shallow Where pavements are laid on 1 to 2 ft. of sand, a good subgrade condition n'ay prevail areas of sand and where the cuts are deep• although faulting at joints is possible er, the problems involved are those of the under heavy axle loads. Drainage is a underlying material. In deep cuts into plastic drift it is particularly necessary to provide intercepting drainage for ground-water flow from the sand-drift bound• ary. Hie grain size of these sands makes them subject to wind erosion, as well as erosion by running water. The lack of binder material leads to problems in em• bankment construction as discussed earlier.

Shallow Sands on Plastic Drift - This clas• sification includes sands of depths to about 3 ft. This type may occur in areas where deep, water-laid sand deposits are bordered by pre-existing areas of drift and also includes areas of shallow wind• blown sand which may or may not be isolated from their source of supply. The surface is well-drained but the drift below nec• essarily has the characteristics of sands- on-drift as described above. The topog• raphy will take the form of the underlying drift with some modifying by the sands, particularly where scattered dunes have formed. Salient features of this soil pattern may be seen in Figure 13. Slopes are gen• erally rather smoothly rounded except at the random dunes. There is little erosion, and phantom drainage may be seen in many Figure 14. Airphoto of Shallow Sands on places. The field pattern is regular and Granular Drift. This airphoto exhibits a some ditching is evident. The smoothly combination of the features of sands super• blended light and dark areas of the plastic imposed on those of granular drift. In• drift pattern are in evidence through the filtration basins are evident and many overlying sand but the overall pattern has muck pockets are seen, some of which are been lightened in color so that the higher outlined on the photo. An area of deeper portions of the terrain show up very light sands and dunes may be observed in the in color tone and the depressed areas are lower right side of the print as indicated not black but gray. by the arrow. This photo is of an area Ihe undulating nature of the topography along Indiana SB No. 17 in western Marshall in this soil area indicates that cuts County. 42 . I and they are underlain by a partially de• problem in the moderate and deep cuts and veloped granular drift P-type horizon with it will be necessary to intercept the the gravelly parent material below. ground-water flow. Frost heaves may be en• Comparison of Figure 14 with Figure 11 countered, not only in the cuts but possibly will show how the surface layer of sand has in other areas where the sand is shallow. modified the airphoto pattern of the granu• Tlie solution for the problems is essen• lar drift. Tbere is still an abundance of tially that of maintaining a high grade steep slopes, slightly modified by the sand. line or of providing a blanket layer in the The gullies are fairly sharp and inflitra- deep cuts and maintaining proper drainage. tion basins are noted. The greatest dif• Shallow Sands on Granular Drift - Again, as ference in the patterns is perhaps the con• was the case with granular drift, the topog• trast in color tones. On the shallow-sand raphy of this soil area tends to be irregu• print, the higher areas are much whiter lar and is influenced almost entirely by than on the granular drift but there are that of the underlying drift. The sands much blacker tones on the shallow-sand tend to modulate the slopes, but there are prints for muck pockets are more prone to occasional dunes providing accents to the develop. Scattered areas of wind-blown topography. The surface is well drained, action may be seen, seme of it still active, largely internally, except in the depress• and native trees cover most of the dunes. ions where muck pockets have formed. Tbe The problems of this soil area, other depth of the sands varies from % to 3 ft. than that of location because of the rou^ topography and muck pockets, are not ex• pected to be great. The change in texture is less sharp than for shallow sands on plastic drift with the result that perfor• mance, even in deep cuts, will not ordin• arily be bad. The soil provides good subgrade support, except possibly in regions of high ground water where there may be appreciable softening of flexible pavements. Sufficient granular material is available for fill as needed. Problems of compaction and erosion, as discussed for sand dunes and ridges, have some application in the shallow sand areas too.

Scattered Areas of Sands on Drift - These soil areas were separated and mapped not because of their importance but because of the danger of including them as sand areas if they were not pointed out. The charac• teristics vary from those of the underlying drift, whether it is plastic or granular, to those of deep sands. The drift pre• dominates, but it may be covered with sand in scattered areas. These sands will vary from thin smears of wind-blown sand only a few inches deep to wind-blown deposits in

Figure 15. Airphoto of Scattered Areas of dune form, the latter sometimes being many Sands on Plastic Drift. This pattern is feet deep. There may also be areas of predominantly that of plastic drift, but water-laid sands which were deposited along superimposed on it are light sand patches shores of small former lakes. As with most as outlined. It represents an area in sand surfaces, the topsoil development is southeast Newton County. • limited, particularly on the slopes. The 43 topography is basically that of the drift, markings make airphoto identification easy. undulating for plastic drift and compara• Color tones are usually dark gray, even tively rough for granular drift, with oc• when not covered by heavy vegetation, be• casional modifications where the sand has cause of the depth of the organic matter caused rounding of the slopes or where in the upper horizons. There will fre• wind-formed dunes have punctuated the high quently be a sharp drop from the upland points of the topography. to the alluvium, and short gullies may Airphoto patterns of this type are occasionally be found cutting down through illustrated by Figures 15 and 16. In the the wal 1. plastic drift areas, the features of the Muck and peat deposits are particularly plastic drift pattern predominate. The numerous in the areas of sand dunes and slopes are smoothly rounded, sometimes ridges and in the other predominantly accentuated by dune formation. The patchy granular soil areas and consequently it is light and dark color tones are occasionally appropriate to discuss them in connection punctuated by a lighter area indicating a with the sand with which they so often oc• sand deposit. Phantom drainage and ditch• cur in conjunction. The deposits may vary ing are prominent. Color tones of the from shallow to great depths and may be pattern in the granular drift area will underlain by sands, gravels, marl, silts, not be greatly changed by the scattered clays, or combinations. Tlie nature of oc- areas of sand since the drift pattern was fairly light due to the well drained nature of the soil. However, the scattered areas of sand may introduce occasional lighter spots. The amount of modification of the pattern is an indication of the depth of the overlying sand; if the pattern is but little modified, there is very little cover; if the pattern is greatly modified, the in• fluence of the sand is evidently stronger. Slopes will be steep and freshly eroded with V-shaped gullies with occasionally a wind-swept appearance to the modifications. Soils in these regions should receive essentially the same consideration as those in the surrounding drift areas. It is im• portant that they not be treated generally as sand areas, particularly in the plastic drift region for the soil type is little better than that of the underlying drift and has the further disadvantage of an ad• ditional change in texture.

Associated Muck, Peat, and Flood Plains - Alluvial areas have been subjected to flooding during comparatively recent times and may currently be liable to flood. They Figure 16. Airphoto of Scattered Areas of are made up of a series of waterlaid de• Sands on Granular Drift. This photo is posits which may vary appreciably in tex• representative of a large portion of western ture. They form an area of possible shift• Fulton County. It has many of the charac• ing stream channel as evidenced by oxbows, teristics of the granular drift pattern but old current marking, meanders, and other is modified with many smoothly rounded like markings (Fig. 17). The soils are slopes of windswept appearance. Color predominantly granular but may be found tones are light and gray except for the with plastic layers. The characteristic muck pockets. 44

Figure 17. Airphoto of Alluvial Soil Are a. This photo shows the alluvial area along the Tippecanoe River in northwest Fulton County, Current scars may be seen as slight variation s in the color tone.

curence of the areas is such that their, consideration. Rather, in construction drainage will be very poor unless they have across these beds it is a problem of de• been thoroughly ditched. The heavy black signing and constructing a fill which will areas are so evident on the airphoto as carry the pavement without settlement. The hardly to require pointing out, the in• problem resolves into either removing the terpretation may rather be one of degree questionable material and backfilling with of development. Figures 18 and 19 are il• a granular material or speeding the con• lustrative of these areas. solidation of the muck and peat so that The highway problem is usually one of detrimental settlement will not occur after carrying the highway across the area be• the pavement has been laid. The failure to cause it cannot be avoided. Alluvial areas accomplish this end is attested to by ob• are generally found parallel to streams, so vious settlements across muck and peat it is as necessary to cross them as it is areas. These problems are currently being to cross streams. A high, level grade is studied by a committee of the Highway Re• usually indicated in both cases; across search Board. alluvium because of projecting the grade line from the level in the upland to the SUMMARY AND CONCLUSIONS level of the bridge crossing (and to stay above flood level) and in muck and peat The basic techniques of interpretation areas because fill is usually required for of aerial photographs for engineering soil foundation support. The matter of founda• characteristics have been applied to an tion support is not likely to be serious extensive and glacially complex areaof in alluvial areas because of their fre• northwest Indiana. Working from techniques quently granular texture. The totally in• of interpretation of airphoto patterns pre• adequate supporting power of muck and peat viously established, using field trips to soils acting as a suhgrade under a pavement aid in classifying areas in which the air• is so well known as not to require any photo pattern was complex, and applying 45

TABLE I

SUMMARY OF AIRPHOTO AND HIOIWAY ENGINEERING CHARACTER I SnCS OF SOIL AREAS

CHARACTCRISTICS AIRPHOTO PATreflNS HICHWAY PROBLEMS

Urge Flat Very Flat over large arena Very flat Faulting Fill acrosa depressions Areaa of Occasional dunes Uniform li^t n-ay color tones Depressions Elevated grade Sands &anular Textures No natural surface drainage Ditching Artificial drainage Ditching Unifonn grain aixe in Oak trees on dunes surface sands Saod dunes Topographically irregular Dkines and ridges Muck Pockets Grass or sod for slope and Ridges Dunes and ridges Blowouts Slope erosion protection Uniform grain size No surface run-off Faulting FilI across muck Muck Pockets Ditching Irregular field pattern Sandy HffC to rolling Gently rolUna to flat High water table Ditching Outwash Little surface drainage More uniform Iigiit gray color Faulting Elevated grade Sandy materials tones No gullies Some ditches Faint infiltration baains Sands and Send topsoil Rollins Muck channels Good construction Gravels Layers of gravels and sanda Few gullies Faulting practices Rolling topography Pitted appearance Well-drained internally Current acars Muck channels Infiltration basins Muck channels Short gullies

Plastic Flat to gently rolling Snoothly-rounded ajopes Very poor subgrede in Blanket layers Drift Impermeable Intense erosion absent cuts Elevated grade Plastic to semi-plsstic patchy li^t and dark Drainage Granular bases merging areas Pumping Deep gutters or Hiantom drainage Froat heevea subdrainage in cuts Rectangular field pattern

Sena-PI a Stic Less regular topography More irregular slopes Poor subgrade in cuts Elevated grade Drift More granular soil Some eroded slopes Drainage Blanket layers Sharper color tone changes Froat action Deep gutters or Phantom drains^ subdrainage in cuta More infiltration basins Granular Often fflorainic Steep slopes Location Slope protection Drift Granular parent soil Freanly-eroded slopes Erosion of cut and Gutters in cuts Steep slopes V-shaped guUiea embankment alopes Good muck Muck arees Light color tonea Fill acrosa muck areas construction Muck pockets

Sands (3 to 5 Variety of underlying anooth slopes Poor subgrade in deep• Blanket layers feet deep) material Some dunes, covered with est cuts Intercepting on Drift Sands are one-sized trees Drainage at soil drainage Some festures of under• Light snd gray color tones boundsriea lying Bsterist in drift-Tike pattern Faulting Dtines PhontotD drainage Shallow Sands Drained surface Plastic drift pattern Poor subgrade in cuts Blanket layers on Plastic In^rnous below underlying Drainage Eleveted ^ade Drifts Occasional dunea Light color on noes Frost heaves Intercepting Gray color in depresaiona drainage Phantom drainage Shallow Sands Irregular topography Send pattern over granular Location for cut and Slope protection on Granular Muck pockets drift pattern fill and to avoid Good embankment Drift Occasional dunes Infiltration baaina muck pockets procedures Well-drained Muck pockets Fill across muck Special muck Slc^e erosion construction Scattered Like plastic drift with Plastic drift patterns with Sane as plastic drift Seme as plastic Areas of Sand some dunes and thin light-colored patches drift on Plastic smears of sand Drift Scattered Like granular drift with (k-anular drift patterns Same as granular drift Some as granular Areas of Sand scattered dunea and thin with light-colored drift on &anular surface smears'Of sand patches Drift Muck and Peat Hetero^neous subsurface Unconformities Support Elevated grade materials Sharp boundaries Drainage Special methoda Low lying Black to dark gray color Settlement of construction Low density tones [fecent Flood Water-laid deposits Low areas Flooding Elevated grade Plains Uesndera Adjvcent to stream Settlement Improved embankment Marsh Dark gray color tonea desi^ end compac• Much vegetation tion methods Current scars. Oxbows 46

Figure 18. Airphoto Showing Stages of Muck Figure 19. Airphoto of Muck Channel Along Development. This picture was taken near Kankakee River. This is the narrowest con• the outwash-sand border in southeast La- striction of the Kankakee basin and the porte County. The black spot in the upper walls, particularly on the right, are quite left corner of the picture is a portion of distinct. The outwash to the right fur• a lake which at one time spread over a much nishes some of the best gravel in Indiana. larger area. The black spot at "A" is a That to the left of the channel is more marsh which has developed in the bed of the sandy. Muck and peat deposits here are former lake. The area surroundingthe many feet deep, causing the uniform flat marsh is enough higher that mucky soils gray color tone. are developing there. terns of both materials, but the combina• knowledge of soils engineering and of geo• tion is a new one. logical and pedological developments in the Results from extensive pavement perfor• area, all or portions of 12 counties were mance surveys make it possible, after the mapped. soils of a given area have been identified It was found that the comparatively com• from the airphotos, to predict the type of plex airphoto patterns of soils in gla• highway performance t'o be expected in that ciated regions can be interpreted, with area or to outline the general features to confidence, to predict the salient charac• be considered in the design of new con• teristics of the soils photographed. The struction. Table 1 is submitted as a sum• method is essentially one of adding to mary of the characteristics of the various knowledge already gained about some pat• soil areas discussed in this report. terns and, by a reasoning process, deter• It may be concluded from the study that: mining how those patterns would be changed (1) Mapping of glacial deposits and re• if the ground they represented were covered worked glacial materials of Wisconsin gla• by some other soil material. For instance, cial origin can be done in considerable de• the pattern of shallow sands on plastic tail where accompanying field investiga• drift shows evidences of the airphoto pat- tions can be made. 47

(2) Complex patterns, or patterns of suggestions throughout the research project combinations of surface soil conditions can summarized here. To Pacifico Montano of usually be identified as combinations of the same staff is due particular appreci• the components of the constituent prints. ation for his unrelenting zeal and skilled Hiis lends support to the belief that simi• assistance, which was a large factor in the lar methods can be applied to many other carrying of this project to its scheduled types of areas. completion. (3) From a knowledge of highway prob• lems in different types of soil areas and from the ability to identify these soil BIBLIOGRAPHY areas on the airphotos, it is possible to predict the type of highway problems to be 1. Belcher, Donald J, The Engineering encountered in a given area by studying the Significance of Soil Patterns; Proceedings, aerial photographs. Twenty-third Annual MeetingHig^iway Research (4) On the basis of observations made, Board. plastic drift, shallow sands on plastic 2. Frost, R. E. and Mollard, J. D.; drift, and scattered areas of sand on plas• New Glacial Features Identified by Air- tic drift along with muck and peat may be photos in Soil Mapping Program; Proceedings, grouped as the soils studied on which the Twenty-sixth Annual Meeting Highway Re• poorest performance is to be expected. search Board. Grouped as soils contributing most to good 3. Woods, K. B. and Gregg, Lowell E,; pavement performance are sands and gravels, Pavement Performance Related to Soil Tex• sandy outwash, large flat areas of sands ture and Compaction; Proceedings, Twenty- (if well drained)^nd areas of sand dunes fourth Annual Meeting Highway Research and ridges (excluding muck pockets). Board. 4. Sweet, Harold S. and Woods, K. B.; Map Cracking in Concrete Pavements as In• fluenced by Soil Texture; Proceedings, ACKNOWLEDGEMENTS Twenty-sixth Annual Weeting Highway Research Board. The author is indebted to Professors 5. Stevens, J. C., Maner, A. W., and K. B. Woods and R. E. Frost. Associate Shelburne, T. E.; Pavement Performance Director and Research Engineer respectively Correlated with Soil Areas; Proceedings of the Joint Highway Research Project at Twenty-ninth Annual Meeting Highway Research Purdue University, for interested help and Board.