GEOLOGICAL SURVEY CIRCULAR 40

August 1950

CONSTRUCTION MATERIALS 

IN DECATUR COUNTY, KANSAS

By

Frank E. Byrne, Henry V. Beck, 

Charles H. Bearman, and Claude W. Matthews

PREPARED IN COOPERATION WITH THE 

STATE HIGHWAY COMMISSION OF KANSAS

R. C. Keeling, State Highway Engineer

S. E. Horner, Chief Geologist 

R. D. Finney, Engineer of Materials

Prepared as Part of a Program

of the Department of the Interior

for Development of the Missouri River Basin
UNITED STATES DEPARTMENT OF THE INTERIOR 

Oscar L. Chapman, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

WASHINGTON, D. C.

Free on application to the Geological Survey, Washington 25, D. C.
INSTRUCTION MATERIALS IN DECATUR COUNTY, KANSAS

Frank E. Byrne, Henry V. Beck, Charles H. Bearman, and Claude W. Matthews

CONTENTS

Page

Introduction................................ 1

Purpose of the investigation............... 1

Area covered by the investigation.......... 1

Geography of the area.................... 1

Investigation procedure................... 1

Acknowledgments........................ 3

Characteristics of the outcropping

stratigraphic units........................ 3

General................................. 3

Smoky Hill chalk member of the

Niobrara formation. ...........*......... 3

Areal distribution................ 3

General description.............. 3

Thickness....................... 3

Construction materials........... 3

Pierre shale............................. 4

Areal distribution................ 4

General description.............. 4

Thickness....................... 4

Construction materials........... 4

Ogallala formation....................... 4

Areal distribution................ 4

General description.............. 4

Representative measured

section....................... 6

Thickness....................... 6

Construction materials..:...;.... 6

Sariborn formation........................ 6

Areal distribution................ 6

General description............... 6

Representative measured

section.................... i.. 7

Thickness....................... -7

Construction materials........... 7

Terrace deposits......................... 7

Areal distribution................ 7

General description.............. 7

Representative measured

section........................ 7

Thickness.............. '. ........ 7

Construction materials......'..... 7

Alluvium................................ 7

Areal distribution................ 7

General description.............. 8

Thickness....................... 8

Construction materials........... 8

Inventory of Construction materials........... 8

General................................. 8

Aggregate for concrete................... 8

Engineering and geologic

characteristics.............. *..... 8

Stratigraphic sources and

performance characteristics........ 8

Inventory of construction materials 

Continued.

Ogallala formation.........

Sanborn formation.........

Terrace deposits..........

Alluvium.................

Road metal.......................

Engineering and geologic 

characteristics..............

Aggregate for concrete. 

Crushed rock*.............

Limestone............

Silicified chalk........

Mortar bed...........

Stratigraphic sources and 

performance characteristics. 

Aggregate for concrete. 

Crushed rock.............

Smoky Hill chalk 

member of the 

Niobrara formation. 

Ogallala formation....

Mineral filler.....................

Engineering and geologic 

characteristics..............

Stratigraphic sources and 

performance characteristics; 

Sanborn formation.........

Terrace deposits..........

Volcanic ash......................

Engineering and geologic 

characteristics.............

Stratigraphic sources and

performance characteristics. 

Riprap...........................

Engineering and geologic 

characteristics.............

Stratigraphic sources and 

performance characteristics. 

Smoky Hill chalk

member of the Niobrara 

formation...............

Ogallala formation..........

Structural stone...................

Engineering and geologic 

characteristics...............

Stratigraphic sources 

and performance 

characteristics..............

Calcareous binder.................

Engineering and geologic 

characteristics..............

Stratigraphic sources 

and performance 

characteristics.............

Page

8

9

9

9

10

10

10

10

10

10

10

10

10

10

10

10

10

11

11

11

11

11

11

11

11

11

11

11
ILLUSTRATIONS

Page

Plate 1. Map showing construction materials and geology of Decatur County, Kansas................. In pocket

Figure 1. Index map of Kansas showing areas covered by this report and by other construction

materials investigations................................................................. 2

2. Outcropping stratigraphic units in Decatur County, Kansas, and their construction

materials.............................................................................. 2

3. Geologic cross section through the North and South Fork Valleys of Sappa Creek................ 5

TABLE 

Table 1. Summary of materials tests.................................................. faces page 8
INTRODUCTION

PURPOSE OF THE INVESTIGATION

The State Highway Commission of Kansas and 

the United States Geological Survey are cooperating 

in the compilation of a State-wide inventory of construction materials. A field party composed of 

personnel from the two agencies investigated sources 

of engineering construction materials in Decatur 

County in the summer of 1947. This report of the 

Decatur County investigation is a part of the Statewide materials inventory and a contribution to the 

geologic mapping and investigation of mineral resources being made in the'Missouri River Basin. I/

The primary objective of the investigation was 

the accumulation of all field and laboratory data pertaining to the geologic materials in Decatur County 

that would be of use in the construction of dams, 

irrigation canals, highways, airports, or other 

engineering structures. Additional geologic data are 

included in this report but only to the extent of providing information useful in the development of the 

construction materials prospects reported in the inventory or for the location of other prospects to meet 

future engineering needs.

AREA COVERED BY THE INVESTIGATION

Decatur County is in the first tier of Kansas 

counties south of the Nebraska border and in the third 

tier east of Colorado (fig. 1). It comprises 25 townships and covers an area of about 900 square miles. 

The county is bounded by parallels 39°34' and 40°00' 

north latitude and meridians 100°II 1 and 100°44i' 

west longitude. It is bounded on the north by Furnas 

and Red Willow Counties, Nebraska, and by the 

following Kansas counties; Norton on the east, 

Sheridan and Thomas on the south, and Rawlins on 

the west.

GEOGRAPHY OF THE AREA

Decatur County is in the High Plains section of 

the Great Plains physiographic province. 2/ The 

divides are flat-topped or gently rolling. They are 

cut by the shallow but fairly steepsided valleys of the 

major streams, which drain toward the east and northeast, and by the shallow valleys of the tributaries to 

these streams. The area of principal relief is along 

Sappa Creek. The stream valley is cut 100 to 150 

feet below the upland surface, as are the lower portions of the tributary valleys. The topography of the 

Sappa Creek belt is of the moderately dissected type. 

A, map contoured by Elias 3/ shows that the tops of 

some of the divides along tRe western boundary of the 

county rise more than 2, 900 feet above Sea level and 

that the flood plains of the major "streams in the eastern part lie below an altitude of 2, 500 feet.

, Three of the principal streams .in the county, 

Sappa Creek, Beaver Creek, and Prairie Dog Creek, 

are in Hie drainage basin of the Republican River. The 

largest of these is Sappa Creek. Both the North and

Missouri River Benin, 78th Cong., 2d sess., S. Doc. 191, 1944, pp. 94-95, 

, appendix in.

Fry*,, J. C., High Plains surface In Kansas: Kama* Acad. Sci. Trans., vol. 49. 

, no. 1, pp. 61-82, June 1946.

Ellas, M. K., Geology of Rawlins and Deeatur Countiee: Kansas Qsal. Survey 

Mln. Res. Circ. 7, pp. 6, 8, fig. 4, 1937.

South Forks of Sappa Creek rise in Sherman County 

about 60 miles to the southwest. They join at a point 

several miles southwe'st of the city of Oberlin, and 

Sappa Creek leaves the county near the northeastern 

corner. Beaver Creek rises in eastern Colorado and 

flows toward the northeast, cutting across the northwestern part of Decatur County. Prairie Dog Creek 

rises about 45 miles to the southwest in Thomas County 

and flows toward the northeast across the southern 

part of Decatur County. The two forks of Prairie Dog 

Creek join at a point about 5 miles west of the city of 

Dresden. The only other major stream in the county 

is the North Fork Solomon River. It rises in Thomas 

County' and flows across the extreme southeastern part 

of Decatur County. The tributaries to the major 

streams are relatively short and flow only intermittently. They enter the major streams at nearly right 

angles.

Three railways serve Decatur County. Oberlin, 

the county seat and principal city, is the terminus of 

a branch line of the Chicago, Burlington, & Quincy 

Railroad. This railroad crosses the central "part of 

the county, and Kanona and Norcatur are located along 

it. One of the main lines of the Chicago, Rock Island, 

& Pacific Railroad cuts across the southeastern corner 

of the county and serves the cities of Leoville, Dresden, 

and Jennings. A second branch line of the Chicago, 

Burlington, & Quincy Railroad crosses the northwestern part of the county, and serves the cities of Traer 

and Cedar Bluffs.

U. S. 36, a major east-west transcontinental 

highway, extends to the east 2 miles north of the 

center of the county. U. S. 183, an important northsouth highway, extends to the south across the county, 

4 miles west of the center. The two highways cross 

at Oberlin. U. S. 383 parallels the Chicago, Rock 

Island & Pacific Railroad across the southeastern 

corner of the county. Kansas Highway 9 starts at 

Dresden and trends eastward across the county. 

Kansas Highway 23 starts at Dresden and trends southward to the county line. There is a well-developed 

system of county and township roads. These roads 

follow section lines for the most part. Some are 

metaled, while others are maintained by grading only.

INVESTIGATION PROCEDURE

This report is based on reconnaissance-type 

field work. The base map (Highway Planning Map, 

scale 1 inch equals 1 mile) was provided by the State 

Highway Commission of Kansas. Drainage lines were 

added to the base map for greater ground control in 

mapping and were taken from a map' (scale 1 inch 

equals 2 miles) compiled from large-scale aerial 

photographs by the Soil Conservation Service, United 

States Department of Agriculture. The areal distribution of the stratigraphic units cropping out in 

Decatur County was then mapped in the field. The 

mapped units are those recognized as of 1947 by the 

United States Geological Survey and the Kansas 

Geological "Survey. Their definitions of the stratigraphic units are accepted with little 0r no modification, because the principal emphasis of the project 

is on construction materials. Geologic problems. 

not critically related to the presentation of information on construction materials are considered to be of

- 1 -
Report in 

preparation

Report 

published

Figure 1. Index map of Kansas showing areas covered by this report and by other 

construction materials investigations

Section

isisssi

*-_-_-_-_-_;

- -_-_-_ _ _

 T^£--- --

£A^.ps3t*~» K 

 5^li$£:£

!?£&&£?

JP&2&& ?f?-.-.".-. -. 

'i&g>"K3&

PBSS^-S

fic«l*»'Jrti5^i»Kj£;

 ~. *TT~ T?"S

Outcrop Thickness 

(feet)

0-30

0-45

0-100

0-150

0-15

0-10

E oj 

« 

</>

Qnaternary

fr '5

V

H

a

Stratigraphic units

c

CC

« 

u 

EL

Pliocene

b

Formations 

and 

members

Altnvinm

Terrace deposits

Sanborn formation

Ogallala formation

/ Pierre shale

/

Niobrara formation 

Smoky Hill Chalk 

member

Generslized description

Silt, tan to dark brown; some clay and' silty sand; 

occasional grsvel lenses.

Upper part, tan or gray silt, often includes a buried 

soil zone; basal psrt, occasionally sandy with local 

gravel lenses included.

Silt, tan, gray, or red-brown locally in basal part; one 

or two bnried soil zones often present; columnar 

structure usually well developed; numerous calcareous nodules or stringers in "B" zone; local lenses 

of sand and gravel in basal pant.

Lenticular ledges of gray mortar bed interbedded 

with lenses of sand, gravel, and silt; hard nodular 

limestone locally present at or near top; interbedded 

lenses of light-gray volcanic ash; basal part locally 

a brown, gray, green, or maroon clay.

Thin-bedded dark-gray clay shale; limonite stains 

along fractures.

Beds of brown silicified chalk separated by thin 

chalky shales.

Construction 

materials

Aggregate 

Road metal

Mineral filler 

Aggregate 

Road metal

Mineral filler 

Aggregate 

Road metal

Aggregate 

Road metal 

Volcanic ash 

Structural stone

%

a Cretaceous system.

b Upper Cretaceous series.

Smoky Hill chalk member of Niobrara formation.

- 2 -
secondary importance and are ignored insofar as the 

validity of the information presented is not affected.

An effort was made to accumulate all existing 

data pertaining to construction materials in the 

county. These data, together with their sources, are 

incorporated in this report. The field parjy also 

collected samples of construction materials not 

reported previously. The samples were brought to 

the- Highway Testing Laboratory of the State Highway 

Commission in Manhattan, Kans., where they were 

subjected to routine laboratory tests. A portion of 

each sample of aggregate material was .analyzed under 

a binocular microscope in the laboratory of the 

Department of Geology, Kansas State College, and 

the constituent rock and mineral grains determined. 

The laboratory tests and mineralogical analyses, 

together with information from other sources, are 

presented in table 1.

ACKNOWLEDGMENTS

Generous assistance in the compilation of the 

area! map and of construction-materials data by the 

following is appreciated: the State Highway Commission of Kansas at Topeka and Manhattan (S. E. 

Horner, chief geologist, and R. D. Finney, engineer 

of materials, and his associates) and'the State 

Geological Survey of Kansas at Lawrence (J. C. Frye, 

executive director).

This report, in manuscript form, was reviewed 

critically by members of the State Highway Commission and the United States Geological Survey. Illustrations were prepared by draftsmen of the State 

Highway Commission and the United States Geological 

Survey.

CHARACTERISTICS-OF THE OUTCROPPING 

STRATIGRAPHIC UNITS

GENERAL

This part of the report discusses the characteristics of each geologic formation or member cropping 

out in Decatur County. The discussion emphasizes 

the areal distribution, general characteristics, and 

thickness of each stratigraphic unit. A representative section is given for each formation or member 

where possible or desirable. The measured sections 

presented in this report are not necessarily intended 

to be complete; their purpose is to show a typical 

section of a formation or member as it occurs in the 

county. The construction materials in each stratigraphic unit are listed also. The principal purpose 

o«f this part of the report is to present the geologic 

information required for the location and the effective 

development of the construction materials contained 

in each stratigraphic unit.

A summary of the geologic constructionmaterials data for each unit is presented in tabular 

form in figure 2. The relations of the stratigraphic 

units to one another are indicated in figure 3.

The areal distribution of the local stratigraphic 

units is shown on plate 1. Each unit is indicated by 

an identifying symbol, and its outcrop areas are 

shown by a distinctive pattern. Railroads, roads, 

and streams are shown to provide a rough basis for

evaluating the accessibility of sources of construction 

materials.

The locations of operated and prospect pits and 

quarries are shown also on plate 1. The symbols indicate whether the pit or quarry is or has been operated or is a prospect, the type of construction 

material available at each site, and the quantity of 

the material (in units of 10,000 cubic yards) that can 

be removed under no more than moderate overburden 

(unconsolidated sediments less than 6 feet thick). 

Symbols shown in vertical letters followed by a number 

(such as ma 12) are listed in table 1. Symbols shown 

in italicized letters (such as mb or fa) are not listed 

in table 1. All materials sources listed in table 1 are 

numbered within each materials classification according to the following plan: The numbering starts in the 

northeasternmost township and continues along the 

same tier to the western boundary of the county. The 

numbering is continued in the next tier south, starting 

with the township in the easternmost range and proceeding to the western boundary of the county, and 

so on. The construction materials sources within a 

township are numbered in the same sequence as are 

the sections.

SMOKY HILL CHALK MEMBER OF 

THE NIOBRARA FORMATION

Areal distribution. The Smoky Hill chalk 

member of the itfiobrara formation (fig. 2) is the 

oldest stratigraphic unit that crops out in Decatur 

County. It was deposited in marine waters. Only two 

small outcrops (pi. 1) of this unit were found in 

Decatur County by the field pasty. Both are cut banks 

along Sappa Creek and occur in the SWi SEi sec. 12 

and the NWi NEi sec. 19, T. IS., R. 26 W. Undoubtedly the Smoky Hill chalk underlies the entire 

area of Decatur County but is concealed elsewhere in 

the county by younger, overlying formations.

General description. The two local outcrops of 

the Smoky Hill chalk undoubtedly are of the upper part 

of the member. The exposed rock consists of layers 

of silicified chalk 0.3 to 0.6 foot thick separated by 

very thin beds of tan chalky shale. The silicified chalk 

is brown with darker brown streaks throughout. The 

original calcium carbonate of the chalk beds probably 

was replaced by silica through the action of silica-rich 

subsurface waters. The limited outcrops of this unit 

account for the lack of a complete description of its 

lithologic and paleontologic characteristics. The outcrops are overlain unconformably-(with an intervening 

erosional break) by terrace deposits. Because of the 

limited thickness of £he exposures of this stratigraphic 

unit a representative section was not measured.

Thickness. The individual outcrops are each 

about 1.5 feet thick. Elias 4/ states that the Niobrara 

formation (composed of the Smoky Hill chalk member 

and the underlying Fort Hays limestone member) is 

only about 300 feet thick in Rawlins and Decatur 

Counties, as interpreted from local well logs.

Construction materials. Because of the limited 

quantity of material available from this stratigraphic 

unit in Decatur County, it probably cannot be considered a source of construction materials. Silicified 

chalk, however, has been used in other counties in

4eiioB, M. K.. op- clt., p. 8.
north-central Kansas as riprap, road metal, and 

structural stone. Additional outcrops of the Smoky 

Hill chalk might possibly be discovered through intensive exploration of the deeper valleys in the 

eastern border region of the county.

PIERRE SHALE

Areal distribution. The Pierre shale (fig. 2) 

is of marine origin and conformably (without an 

intervening erosional break) overlies the Smoky Hill 

chalk member of the Niobrara formation. Only one 

outcrop of the Pierre shale (pi. 1) was found by the 

field party in Decatur County. This is an artificial 

outcrop, because the formation is exposed in a road 

cut along U. -S. Highway 383 in the SWi NEi sec. 10, 

T. 4 S. , R. 26 W. Material identified by the field 

party as Pierre shale was encountered in an auger 

hole drilled in the SWi NWi sec. 6, T. 4 S. , R. 30 W. 

beneath 7 feet of sand and gravel of Quaternary age.

Elias _5/ reports that the Pierre shale crops out 

in the valley~of Beaver Creek, in some of its tributary valleys, and in the valley of Sappa Creek. An 

examination of the reported outcrop areas failed to 

reveal the formation, although a more intensive investigation might prove successful. Undoubtedly the 

Pierre shale underlies most of Decatur County but is 

obscured beneath younger Tertiary and Quaternary 

sediments (fig. 3), from which it is separated by an 

unconformity.

General description. The Pierre shale is- composed predominantly oj a thin bedded to very thin 

bedded, dark-gray or black clay shale. It weathers 

light gray. Fracture planes are conspicuously 

limonite stained. The Pierre shale is so homogeneous 

in the exposure examined by the field party that a section of it was not measured.

Thickness. The thickness of the one local outcrop of the Pierre shale examined is about 5 feet. 

Undoubtedly this is only a small part of the full thickness of the formation, for Elias _6/ reports that 600 

feet of the formation was encountered in drilling a 

well in the vicinity of Kanona and that the formation 

thickens toward the west to 900 to 1, 200 feet in 

Rawlins County.

Construction materials. The clay shales of 

this stratigraphic unit are probably of little or no 

value as materials for engineering construction.

OGALLALA FORMATION

distribution. The Ogallala formation 

(fig. 2) crops out locally along the valley walls of the 

larger streams and their tributaries in Decatur County 

(pi. 1) . The outcrops are discontinuous, because this 

formation is generally buried beneath the younger, 

overlying Sanborn formation. The Ogallala formation 

undoubtedly underlies all of the larger divide areas in 

the county but is exposed only where streams have cut 

through overlying Sanborn formation.

General description. --The Ogallala formation 

overlies the Smoky Hill chalk member of the Niobrara 

formation in the eastern part of the county and the 

Pierre shale throughout the remainder of the county

 JEllas, M. K., op. cit., p. 6. 

6Elias, M. K.. op. clt., p. 8.

- 4 -

(fig. 3). It is separated by an unconformity from 

these older stratigraphic units. It is overlain unconformably by the Sanborn formation.

The Ogallala formation includes interbedded 

lenses of silt, clay, and cross-bedded sands and 

gravels. The lenses vary in both thickness and extent 

and thus indicate the stream-deposited origin of much 

of the formation. The bulk of the material composing 

the Ogallala was eroded from the Rocky Mountains by 

streams, which then transported the sediments toward 

the east and deposited them as a sedimentary layer 

over the High Plains surface.

The Ogallala formation in Decatur County is 

characterized especially by lenticular layers of mortar 

bed. The mortar bed lenses are light gray and are 

composed of sand and/or gravel cemented by interstitial deposits of calcium carbonate. The degree of 

cementation varies and influences the hardness of each 

mortar bed layer; the most firmly cemented layers 

are the hardest. Because of their superior hardness, 

as compared with that of the other materials composing 

this formation, the mortar beds crop out as conspicuous hillside ledges. So many ledges occur in Decatur 

County that some hillsides, often as high as 50 feet, 

appear to be entirely underlain by mortar bed material. 

Careful examination reveals, however, that even in 

such situations the mortar beds are interbedded with 

poorly cemented sands, gravels, and silts and mask 

the hills only because they are less easily eroded. 

Individual mortar beds average about 6 feet in thickness, but locally they may be as much as 18 to 20 

feet thick. Clay balls are fairly numerous in the 

mortar beds. The poorly cemented sediments average 

about 4 feet in thickness.

Fairly thick beds of maroon, green, and brown 

clays occur in various parts of Decatur County (see 

representative measured section). Some zones have 

been sufficiently compacted to form shales. They are 

either laminated or massive, and they may contain 

scattered calcareous concretions. It is thought that 

the clays and the clay shales are a basal phase of the 

Ogallala formation. Similar materials were found by 

the field party working in Norton County and have been 

reported in other northwestern Kansas localities.

The loosely cemented sands and gravels in the 

Ogallala formation often are hard to distinguish from 

local sands and gravels in the basal part of the 

Sanborn formation. This distinction can be made 

readily if the mortar beds of the Ogallala are in direct 

association with sand and gravel lenses. Lacking this 

association, the correlation of such sand and gravel 

layers is based on topographic position and the presence of certain mineral and rock fragments considered 

to be indicative of the Sanborn formation. The presence of numerous particles of mortar bed or other 

typical materials of the Ogallala in the sand and gravel 

is interpreted as indicating that the deposit is to be 

classified as Sanborn formation.

A dense nodular massive buff-gray limestone 

occurs locally in the upper part of the Ogallala formation. It is lighter in color, finer textured, and 

generally much harder than the mortar beds of the 

Ogallala. This phase of the Ogallala formation contains only scattered sand grains and is thought to 

represent a surface or near-surface caliche deposited 

through the evaporation of subsurface waters heavily
Scale

2 miles

Explanation

Assumed contact without

Assumed contact with

Pterre shale Contact with erosional 

break

Sand with 

gravel lenses

Figure 3.-Geologic cross section through the North and South Fork Valleys 

of Sappa Creek along the line between sees. 32 and 33, T. 3 S.,R.30W., 

and sees. 20 and 21, T. 4 S.,R. 30 W.

- 5 -
charged with dissolved calcium carbonate. The lime-" 

stone was examined in two quarries; in the NEi SWi 

sec. 29, T. 4 S./R. 26 W. and in the SW| Nw| sec. 

25, T. IS., R. - 2? W. The beds have an average 

thickness of about 2 feet.

Two lenses of volcanic ash of Ogallala age were 

located by the Decatur County field party. The ash 

is white to light gray, is relatively free of extraneous 

material, and appears to be somewhat more compacted than the volcanic ash found in younger stratigraphic units. The ash is material discharged into 

the atmosphere during the explosive phase of a volcanic eruption-. It was carried by the wind and deposited in1 such sheltered places as stream valleys 

and river basins. The two localities are listed in 

table 1 (va.l and 2) and mapped on plate 1.

A fossil plant, Biorbia, fossilia, was recognized 

in this formation in Decatur County. Other types of 

fossils have been reported in the Ogallala but were 

not found by the Decatur County field party.

The quartzite lenses so characteristic of the 

Ogallala formation in other parts of Kansas were not 

found in Decatur County.

Representative measured section. --A section of 

the Ogallala formation is exhibited in a cut bank of a 

Sappa Creek tributary in the NW| NWi sec. 2, T. 2 S., 

R. 28 W., as follows:

Feet

(Overlain by silt of the Sanborn formation) 

Ogallala formation:

Mortar bed, firmly cemented; two 

prominent ledges that crop out 

on hillside; intervening beds 

covered............................ 18.0

Silt, sandy; gray, weathers light 

gray............................... .15

Flintlike bed; hard; .somewhat caU 

careous; light gray.................. .5

Shale; dark green, weathers light 

green; contains numerous calcareous concretions................. 1. 3

Zone of calcareous concretions......... .15

Shale; laminated; maroon, weathers 

pink................................ .55

Clay, silty; laminated; light 

brown, weathers gray................ .1

Shale; maroon, weathers pink; 

numerous calcareous concretions in basal part................ .85

Clay, silty; light brown, wea- 

 thers grayish green.................. .15

Shale; maroon, weathers pink........... .45

Clay, silty; gray brown, weathers gray green..................... .15

Shale; maroon, weathers pink; . 

scattered calcareous concretions...... 2.1

Clay, sandy; brown..................... .2

Zone of flinty nodules................... .1

Sand, very fine; light brown; very 

thin layers of silt interbedded.......... .65

Clay; yellow brown, weathers

light brown.......................... 2.0

Total thickness exposed

(base covered)...................... 27.40

- 6-

Thickness. The thickness of the Ogallala formation ranges from a feather edge along the valleys 

of the major streams to an estimated maximum of 

about 200 feet. The average thickness of the formation 

is thought to be about 150 feet. Individual outcrops 

have an average thickness of about 20 feet, although, 

in the northwestern part of the county, the thickness of 

the Ogallala formation exposed through the overlying 

Sanborn formation averages about 50 feet.

Construction materials.« 

Aggregate for concrete. 

Road metal. 

Volcanic ash. 

Structural stone. 

Riprap.

SAN&ORN FORMATION

Area! distribution. --The Sanborn formation 

(fig. 2) is the most widely distributed stratigraphic. 

unit cropping out in Decatur County (pi. 1). It occurs 

as an extensive blanket of silt of variable thickness 

capping the divides and as a discontinuous deposit of 

silt part way up the valley walls of some of the larger 

streams in the county, such as Sappa Creek. The 

discontinuous phase is not as conspicuously developed 

in Decatur County as it is in counties to the east. The 

two phases of the Sanborn formation are mapped as a 

single stratigraphic unit because their lithologic characters are similar.

General description. 7-The Sanborn formation is 

composed of materials deposited by streams, slope 

wash, and wind and through the action of gravity. Frye 

and Fent 7/ have subdivided the formation into members. It was not feasible to attempt the mapping of 

such members in the reconnaissance-type field work 

on which this report is based. To/'do so would require 

a greatly expanded field program, including test drilling. The Sanborn formation as it is here defined and 

mapped seems adequate to serve the purpose of a construction materials inventory.

The Sanborn formation unconformably overlies 

all older stratigraphic units with which it is in contact. 

Silt-size particles predominate in the upper part of the 

formation. The color is generally light tan but locally 

may be light gray. The typical silts of the lower part 

of the formation are dull red. There is a prominent 

soil profile at the top of the formation, and one or more 

buried soil zones have been reported by Hibbard, Frye, 

and Leonard. 8/ The "A" zone of the soil profile varies 

in thickness from about 0.9 foot to 1.9 feet. The "B" 

zone is several times as thick and is characterized by 

secondary calcium carbonate deposited by percolating 

subsurface waters as nodules, stringers, or impregnations. The amount of calcium carbonate in the "C" 

zone of the soil profile is relatively negligible. A 

.crude columnar structure is often developed in the 

upper part of the Sanborn and is the result of the intersection of irregular joint planes. Silts of the Sanborn 

formation tend to stand in vertical banks.

In addition to the red silt, the basal part of the 

formation locally includes lenses of cross-bedded silty 

sand and/or gravel usually from 4 to 6 feet thick. 

These are channel deposits that pinch out within

Frye, J. C., and Fent, O. S., Late Pleistocene loesses of central Kansas:

Kansas GeoL Sirvey Bull. 70, pt. 3, pp. 41-51, 1947.

*HJbbard, C. W., Fry*, J. C., and Leonard, A. B., Reconnaissance of Pleistocene 

deposits to north-central Kansas: Kansas Geol. Survey Bull. 52, pt. 1, p. 13, 

1944.
relatively short distances. Weathered and waterrounded particles of the mortar bed of the Ogallala 

are conspicuous in the gravels.

Fossil shells oi gastropods (snails) were 

collected from several outcrops of the Sanborn formation by the field party. The specimens included 

both high-spired and low*-spired types. Fragments 

of the skeletons of vertebrate animals are reported 

to be fairly common in the basal part of the formation.

The Sanborn formation generally erodes to form 

a gently undulating surface. The gently sloping walls 

of the"headward portions of numerous small tributary 

valleys exhibit a phenomenon known as "catstep 

erosion. " This is probably the result of gravity 

sliding of water-saturated silt down toward the tributary streams. The "catsteps" are bounded by 

scarps a foot or more high, which define slump 

blocks from several feet to about 20 feet-wide. The 

catsteps may develop in two or more series.

The Sanborn formation is more extensive and 

is thicker along the north walls of the major stream 

valleys than it is along the south walls. This causes 

the north walls to be gently sloping and the south 

valley walls to be much more steep. Most of the exposures of older stratigraphic units, therefore, occur 

along, the south valley walls.

Representative measured section. A road cut 

in the SEt SE± sec. 9, T. 1 S., R. 30 W. shows the 

following section of the Sanborn formation:

Feet

Sanborn formation:

Soil zone; sUty, tan gray;............. 0.5

Silt; brown; well*developed 

columnar structure................. 3.4

Silt; light buff; shows crude 

columnar structure; numerous 

stringers of calcium carbonate. ............ *............... 2,3

Silt; occasional granitic pebbles 

scattered throughout; light 

buff; fossil snails in basal part....... 5.3

Sand, silty; pebbles as much as 

0. 5 inch in diameter scattered 

throughout; numerous calcareous nodules.................... 4.6

Silt, very fine; light buff; occasional thin lenses' of fine sand 

interbedded........................ 8.1

Sand; cross-bedded; numerous 

* rounded mortar-bed pebbles 

in basal part; some irregular 

lenses of silt interbedded............. 12.3

Silt, fine; tan........................ 1.5

Total thickness exposed

(base covered)....................... 38.0

Thickness. --The thickness of this formation 

varies greatly over the county. In the vicinity of the 

stream valleys it may be only a feather edge, but . near the tops of the divides it is estimated to be as 

much as 50 feet thick. The average thickness is about 

75 feet.

Construction materials. 

Aggregate for concrete. 

Road metal. 

Mineral filler.

TERRACE DEPOSITS

Areal distribution. Terrace deposits (fig. 2) 

are conspicuous features in the valleys of the major 

streams in Decatur County (pi.. 1). Fingerlike extensions of the terrace deposits project into the" 

valleys of the larger tributaries. The terraces of 

Sappa Creek range from about 0. 5 mile to 1. 3 miles 

in width, those "of Prairie Dog Creek average about 

0. 5 mile, those of the Solomon River about 1 mile, 

and those of Beaver Creek about 1.5 miles in width. 

Two or more terrace levels are present but are mapped 

as a single stratigraphic unit because of their lithoiogic 

similarity.

General description. The terrace deposits unconformabiy overlie older formations (fig. 3) and are 

composed of materials deposited by present-day 

streams in earlier gradational cycles. The upper part 

of a terrace is composed of a tan or gray silt that exhibits many of the characteristics listed for the 

Sanborn formation. There is a well-developed soil 

profile, there may lie one or more buried soil aones, 

it often develops columnar structure, and locally it 

contains the shells of fossil gastropods. There are 

lenses of cross-bedded sand and gravel in the basal 

part of the formation. The sand and gravel particles 

are from local older stratigraphic units that have been 

reworked by streams in later gradational cycles.

Representative measured section. The following 

section of a terrace deposit in the valley of Prairie 

Dog Creek was measured in a road cut in the SE-| NEi 

sec. 11, T. 4 S., R. 26 W.:

Feet 

Quaternary terrace deposits:

Soil zone; dark gray................... 3. 5

Silt, very fine; light brown to

buff................................. 2.1 *

Silt, fine; lime stained; light

gray to buff..................."...... 3.7

Silt, fine; light tan to buff.............. 1.6

Silt, sandy; light buff.................. 1.6

Total thickness exposed

(base covered)....................... 12.9

Thickness. The thickness of the terrace d«- 

posits is exceedingly variable and could have been 

determined accurately only by test drilling. Such data 

is not available for Decatur County, but it is estimated 

that the maximum thickness is about 45 feet. The 

terrace extensions into the smaller tributary valleys 

probably have an average thickness of no more than 

10 to 15 feet.

Construction materials. 

Aggregate for concrete. 

Road metal. 

Mineral iiller,

ALLUVIUM

Areal distributions. --The deposits (fig. 2) formed

-7-
by streams in their present gradations! cycles are 

mapped as alluvium (pi. 1). They constitute the most 

recent stratigraphic unit in Decatur County. Alluvium 

is defined in this report as the material underlying 

the present flood plain of a stream. This flood plain 

is the area adjacent to the stream channel that is 

covered by water during a normal flood stage.

Alluvium in the valleys of the Solomon River, 

Prairie Dog Creek, Sappa Creek, and Beaver Creek 

is mapped. Alluvial deposits also are present in 

tributary valleys but are so narrow that they could 

not be shown on a map scaled to 1 mile to 1 inch. 

The alluvial deposits along the major streams have 

an average width of about 0.25 mile.

General description. The alluvium is composed predominantly of tan or dark-gray silt. Local 

channel fills in the main mass of the alluvium are 

composed of sand-size and gravel-size particles. 

High percentages of local mortar-bed fragments are 

characteristic of the gravels. Fossil shells of gastropods were collected by the field party from cut 

banks in the alluvium of Decatur County. It was not 

possible to measure a section representative of this 

formation because of the low relief of the alluvium.

Thickness. The thickness of tRe alluvium' 

could not be determined because of the absence of 

test-drilling data. The maximum thickness of the 

alluvium in the major stream valleys is estimated to 

be about 30 feet.

Construction materials. -- 

Aggregate for concrete. 

Road metal.

INVENTORY OF CONSTRUCTION MATERIALS 

GENERAL

This part of the report inventories the construction materials in Decatur County. Its objectives 

are to establish the bases upon which the construction 

' materials are classified and to analyze the relations 

of the various materials to the stratigraphic units in 

which they occur.

Laboratory test data have been introduced into 

the report whenever available to aid in the evaluation 

of the materials. This information is given in table 

1 and is based on standard testing procedures. 9/ It 

is expected that the materials prospects listedTn this 

report will be proved by subsequent augering, drilling, 

or test pitting and that the materials themselves will 

be subjected to laboratory testing prior to the development of a site.

Although numerous prospect pits and quarries 

were located in the field, no attempt was made to 

complete an exhaustive materials location survey. 

[ The purposes of this report are to inventory the 

construction materials that occur in Decatur County 

and to establish the geologic pattern required for the 

location and development of the materials which 

future engineering needs may demand. ]

'State Highway Commission of Kansas, Standard specifications for State road and 

bridge construction, 1945: Gradation factor, p. 16; Sieve analysis, pp. 333-334; 

Soundness, pp. 335-336. American Association of State Highway Officials, 

Standard specifications for highway materials and methods of sampling and 

testing, pt. 2, 1947: Absorption, pp. 251-252; Compresslve sfrength, pp. 

257-258; Dewal abrasion; pp. 235-236; Uquid limit, pp. 198-201; Los Ample* 

abrasion, pp. 237-239; Plastic limit, pp. 202-203; Specific amity, pp. 2 49-2SO; 

Toughness, pp. 240-241; Weight per cubic foot, pp. 253-854. g

AGGREGATE FOR CONCRETE 

ENGINEERING AND GEOLOGIC CHARACTERISTICS

Aggregates for concrete are distinguished as 

"fine aggregates" and "mixed aggregates" in table 1 

and on plate 1. The distinction is an arbitrary one 

based on the percentage of material retained on a 

standard no. 4 sieve. The portion of a sample retained on the sieve is designated as the coarse fraction. 

The sample material is classified as a mixed aggregate 

if the coarse fraction is 5 percent or more by weight 

of the whole sample; as a fine aggregate if the coarse 

fraction is less than 5 percent. Fine and mixed "aggregates will be discussed under a single heading, "Aggregate for concrete," because the grading of almost any 

aggregate material may be changed by sweetening or 

by screening to conform to required specifications.

Aggregates for concrete consist of sand-size' 

and/or gravel-size fragments of hard, durable 

minerals and/or rocks. The constituent particles are 

free from adherent coatings that would interfere with 

the bonding of cement with the particles. The presence of the following deleterious substances, if in 

quantities thought to be excessive in a concrete aggregate, is noted under Remarks in table 1: material 

passing the no. 200 sieve (wash); shaly, soft, or flaky 

fragments; sticks or other organic debris; clay lumps; 

and minerals which, because of their chemical composition, may react with the cement to the detriment 

of the concrete.

The materials reported in this classification 

are exposed at the surface or are under unconsolidated 

overburden sufficiently thin for them to be economically 

developed. Relatively inaccessible deposits and deposits of sand and gravel overlain by thick or consolidated beds usually are not included in this classification because of the added expense in the removal of the 

overburden; exceptions to this practice are noted in 

the "Remarks" column of table 1.

The test characteristics of some of the materials 

included under this heading indicate that they might be 

acceptable for other uses of aggregate, such as aggregate for bituminous concrete or cover material, even 

though they are below the standard required of aggregate used in Portland-cement concrete.

STRATIGRAPHIC SOURCES AND PERFORMANCE CHARACTERISTICS

The following stratigraphic units are actual or 

potential sources of aggregate for concrete in Decatur 

County:

(1) Qgallala formation. This formation is 

probaoly the most promising source of aggregate for 

concrete in Decatur County, Nine samples of fine 

aggregate (fa 2, 3, 5, 8, 9, and 12-15) and 6 samples 

of mixed aggregate (ma 3, 4, 11, and 15-17) were 

taken from this stratigraphic unit. Their locations are 

mapped on plate 1, and their test characteristics are 

given in table 1. The coarse fractions of both types of 

aggregate are composed predominantly of quartz and 

feldspar particles and contain minor amounts of fragments of basic igneous rocks. The fine fractions are 

composed mainly of quartz grains, but there are numerous feldspar grains and some basic igneous rock 

and quartzite particles. Quartzite is the only constituent present that might be deleterious in concrete
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Date of test

Percent on 

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no. 4

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no. 16

Percent on 

no. IOO

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Description ofthematerial |

Laboratory testdata

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aggregate, but it occurs in such small amounts as to 

be negligible;

Laboratory test data indicate that some of the 

sands and gravels of the Ogallala formation may be 

acceptable as aggregate for concrete. The average 

specific gravity of the samples tested is about 2,6; 

the gradation factors are usually satisfactory; the 

compressive strength ratios are generally within 

acceptable limits, but those of samples fa 2, 1-3, 15 

and nia 3 are substandard; and the one sample (ma 11) 

tested for soundness indicates that sands and gravels 

of the Ogallala probably are sound. The percentage 

of wash is fairly high in most samples and is very 

high in fa 14. Engineers consulted in Decatur County 

seem to be of the opinion that all local sources, including the, Ogallala formation, provide only inferior 

aggregate for use in Portland-cement concrete.

Additional sources of aggregate occur in the 

Ogallala formation essentially throughout the area of 

its outcrop. In many places, however, the sand and 

gravel lenses are under an overburden of relatively 

hard mortar bed, and their development would not be x< 

economical,

IS ^Sanborn formation. Two samples of fine 

aggregate (fa 4 and 7) and 3 of mixed aggregate (ina 1, 

2, and 7) were collected from the Sanborn formation. 

Mineral analyses indicate that both coarse and fine 

fractions are composed predominantly of quartz particles, with minor amounts of feldspar, basic igneous 

rock, and mortar-bed fragments also present. The 

three mixed aggregates tested contained 20 percent or 

more of mortar-bed fragments. Such fragments in 

the gravels of the Sanborn are relatively hard and 

durable and are not considered to be deleterious.

The test characteristics of sands and gravels 

of the Sanborn formation indicate that some of them 

may be acceptable as aggregate for concrete. Their 

average specific gravity is between 2.5 and 2. 8, the 

gradation factor is within specified limits or only 

slightly below the minimum, and the compressive 

strength ratios are satisfactory. In one sample tested, 

ma 2, the percentage of wash (10.4) probably is excessive.

Intensive exploration of the basal part of the 

Sanborn formation undoubtedly would result in the 

discovery of additional channel fills of sand and gravel. 

Exploration probably would be most productive in 

areas where tributary streams have cut deep into the 

formation. Because of the lenticular character of the 

channel fills it is likely that they will yield aggregate 

materials in limited quantities only.

(3) Terrace deposits. --The terrace deposits 

constitute another potential source of aggregate for 

concrete in Decatur County. Four samples of fine 

aggregate (fa 1, 6, 10, and 11) and five samples of 

mixed aggregate (ma 5, 6, and 12-14) were obtained 

from this formation. The sample locations are 

mapped on plate 1 and the mineral and test characteristics are given in table 1.

The constituent mineral grains are predominantly quartz and feldspar. Minor amounts of particles of basic igneous rock, mortar bed, and chalk 

are also present. Traces of quartzite particles occur

in some of the samples analyzed but not in sufficient 

abundance to be considered deleterious. The percentage of wash, however, is rather high, as in samples 

fa 1, 10, and 11. Otherwise the test data indicate the 

terrace deposits may yield acceptable aggregates for 

concrete. The average specific gravity of the samples 

tested is about 2.6, and the compressive strength 

ratios for most samples are generally within required 

limits.

Intensive exploration of th© basal part of the 

terrace deposits undoubtedly would yield additional 

sources of sand and gravel. The beds, however, are 

lenticular, and the quantities of material available 

necessarily would be rather limited.

i*J Alluvium. --The three samples of alluvium 

tested (ma 8-10) are classified as mixed aggregate. 

Mineral analyses were not made for these samples 

inasmuch as they had been collected prior to the 1947 

field season. The materials descriptions indicate, however, that the most numerous particles are probably 

quartz and feldspar but with minor amounts of calcareous rock fragments, as perhaps mortar bed and chalk, 

also present. The test characteristics of alluvial 

samples are all within acceptable limits. Two samples, 

ma 8 and 10, contain minor amounts of mud balls.

The alluvial sands and gravels occur in lenticular 

channel deposits in the flood plains of the larger 

streams in the county. Additional sources may be located by exploring the alluvial deposits. The sand and 

gravel channel fills are relatively narrow but fairly 

long lenses in the silt that composes the bulk of the 

alluvium.

ROAD METAL 

ENGINEERING AND GEOLOGIC CHARACTERISTICS

Road metal, known also as surfacing material, 

crushed stone, and aggregate, is defined in this report 

as any material that may be applied to a road to improve the performance characteristics of that road. 

Many geologic materials fulfill this requirement, and 

the list of such materials will vary from one area to 

the next. The following materials have been used in 

Decatur County, or are available for use, as road 

metal:

(I) Aggregate for concrete.

Crushed rock. Indurated rocks are avail-

-Q.

able inDecaiur County for use as crushed stone in 

road construction or as railway ballast. The rocks 

are;

(a) Limestone, a compact massive layer 

of calcareous material, variable in its hardness.

(b) Silicified chalk, a compact massive 

layer of material originally calcareous but more 

or less completely replaced by silica. The known 

deposits of Silicified chalk in Decatur County are 

not mapped on plate I because of the limited 

quantities of material available in them.

(c) Mortar bed, a massive compact rock 

of variable hardness composed of sand and/or 

gravel particles more or less firmly cemented 

by interstitial calcium carbonate.
These materials are mapped on platfe 1 as limestone and mortar bed. The test characteristics for 

mortar bed are given in table 1. In addition to their 

uses as road metal or ballast, they may be used as 

structural stone and riprap.

STRATIGRAPHIC SOURCES AND PERFORMANCE CHARACTERISTICS

(1) Aggregate for concrete. The materials discussecTpreviously as aggregate for concrete have also 

been used in the construction of bituminous mat roads 

and as surfacing material on many light-traffic roads 

within the county. Local sources of information indicate that the bulk of the aggregates so used in Decatur 

County have been shipped in from Nebraska.

(2) Crushed rock. 

(a) Smoky Hill chalk member of the 

Niobrara formation. Beds of silicified chalk in 

the Smoky Hill chalk member are sources of 

crushed rock used in road construction in other 

north-central and northwestern Kansas counties. 

Field examination of this material exposed in 

Decatur County indicated that it is acceptable 

for this use. The limited quantity of material 

available, however, suggests that the local 

supply is inadequate. It is possible that intensive exploration of the deeper valleys in the 

eastern part of Decatur County might reveal 

additional sources of silicified chalk not found 

by the field party.

(b) Ogallala formation. Two types of 

material occur in the Ogallala formation that 

might be used as crushed rock for road construction. The dense, compact, hard nodular limestone in the upper part of the formation has been 

used for this purpose elsewhere in north-central 

Kansas but not in Decatur County. Field examination of such uses indicates that the material is 

acceptable. The amount of this material available locally appears to be rather limited, but 

additional sources of it may be-discovered by 

intensive prospecting of the upper part of the 

Ogallala formation. Two quarries opened in 

beds of nodular limestone are mapped on plate 

1, in the SWi NEi sec. 25, T. IS., R. 27 W., 

and in the NEi SWi sec. 29, T. 4 S., R. 26 W.

Mortar-bed ledges in the Ogallala formation 

have been quarried and the material crushed and 

applied to light-traffic roads in other counties in 

north-central Kansas. The calcium carbonate in the 

mortar bed serves as a binder for the particles of 

§and and gravel, and the crushed mortar-bed material 

is compacted by traffic into a type of macadam. The 

quantity of mortar-bed material in Decatur County is 

essentially unlimited. Numerous operated and prospect quarry sites are mapped on plate 1, but additional 

quarries could be opened at convenient places in nearly 

all parts of the county.

MINERAL FILLER 

ENGINEERING AND GEOLOGIC CHARACTERISTICS

Material composed predominantly of silt-size 

mineral particles, 50 percent or more of which pass 

the no. 200 sieve, is classified in this report as

-10-

mineral filler. It has no more than a trace of sticks 

or other organic debris but may contain minor amounts 

of fine sand and/or clay. The State Highway Commission of Kansas 10/ states that the material will qualify 

for mineral filler only if laboratory tests indicate a 

low coefficient of cementation. Deficiencies of the 

tested samples in this respect are noted under Remarks 

in table 1. Failure of the material to pulverize easily, 

a factor of cementation, increases the difficulty of 

obtaining its uniform distribution throughout the mix 

ture,

STRATIGRAPHIC SOURCES AND PERFORMANCE CHARACTERISTICS

(1) Sanbprn formation. Two samples of mineral 

filler tnif 1 and 3) were obtained from the Sanborn formation, and the test data are included in table 1. The 

sample locations are mapped on plate 1. Sieve analyses indicate that the material is acceptable for this use, 

but the cementation factor for each one is probably excessive. In all probability, the samples were taken 

from the "B" zone of the soil profile, for the high 

cementation is undoubtedly a factor of impregnation of 

the material with calcium carbonate deposited through 

the action of percolating subsurface waters. Silt in 

the Sanborn taken from below the "B" zone very likely 

will have a cementation factor within acceptable limits. 

This stratigraphic unit is the principal source of mineral filler in Decatur County, and because of the widespread availability of the material it was not thought 

necessary to map any more than these two prospects. 

Pits can be opened in the formation wherever its use in 

engineering construction is desired. It is recommended 

that, prior to development of a site, the material be 

laboratory tested and its cementation factor determined,

(2) Terrace deposits. One sample of silt from 

a terrace deposit (mf 2) was tested, and the data are 

included in table 1. The sample location is mapped on 

plate 1. The test characteristics of this sample are 

very similar to those of the mineral filler samples 

from the Sanborn. The cementation factor (80) again 

is high and may be excessive. Laboratory testing 

prior to development of any one materials site is recommended.

VOLCANIC ASH 

ENGINEERING AND GEOLOGIC CHARACTERISTICS

Volcanic ash is sometimes classified as mineral 

filler, but in this report it is distinguished as a special 

type of mineral filler, because it is suitable for certain 

uses that the usual silty filler is not. Volcanic ash 

consists predominantly of the fine glass-like shards 

ejected during the explosive phase of a volcanic eruption. The material may .include clay-size or silt-size 

particles of other origins and occasional thin seams of 

gravel and sand.

STRATIGRAPHIC SOURCES AND PERFORMANCE CHARACTERISTICS

Two samples of volcanic ash (va 1 and 2) were 

collected by the field party and tested in the Highway 

Materials Laboratory. The test data are included in 

table 1, and the sample locations are mapped on plate 

1. Volcanic ash in Decatur County was found in commercial quantities in the Ogallala formation only.

10Bcrn«, S. E., chiaf geologist. State Highway Commission of Kansas, letter 

dated January 4, 1947.
Thin lenses of impure ash occur in the basal part of 

the Sanborn formation, but the field "party found none 

in commercial quantity. The test characteristics 

indicate that the- volcanic ash of the OgaLLala is satisfactory for use in engineering construction.

Other lenses of volcanic ash undoubtedly occur 

in the Ogallala formation and may be discovered by 

intensive field exploration of the mapped outcrop 

areas. It is entirely likely that commercial quantities 

of volcanic ash may be located in the basal part of the 

Sanborn formation, for in other Kansas counties this 

stratigraphic unit is an important source of volcanic 

ash.

RIPRAP 

ENGINEERING AND GEOLOGIC CHARACTERISTICS

Riprap, as defined in this report, is any material 

suitable for protecting earthen fills from erosion. Tc 

be acceptable for this use the material must be relatively sound and free from cracks and other structural 

defects or impurities that would cause it to disintegrate through abrasion, slaking, or freeze-and-thaw. 

It is desirable that the material be in blocks having 

approximately rectangular faces 7 inches or more in 

width and that the specific gravity ba 2 or higher.

STRATIGRAPHIC SOURCES AND PERFORMANCE CHARACTERISTICS

(1) Smoky Hill chalk member of the Niobrara 

formation. The silicified chalk beds oFthis stratigraphic unit, which have been described previously, 

appear acceptable as riprap for earthen structures. 

The outcrops were not sampled because they did not 

contain material in commercial quantity.

(2) Qgallala formation. Two of the sedimentary 

materials Included in the Ogallala formation might 

prove acceptable as riprap. The dense nodular limestone described as occurring in the upper part of the 

formation has been used elsewhere in Kansas as riprap. Field examination indicates that it is satisfactory 

for this use. No local deposits of the limestone known 

at present occur in adequate quantities, but additional 

deposits may be discovered through the intensive exploration of the outcrop areas of the Ogallala.

Certain of the mortar-bed ledges in the Ogallala 

formation are unusually firmly cemented and approach 

the average limestone in hardness. The test characteristics of one mortar-be(d ledge (nib 1) are given in 

table 1, and the sample location is mapped on plate 1. 

The soundness factor of this one sample is relatively 

low, but, judged by field comparison with other ledges 

in Decatur County, more satisfactory mortar-bed materials are available locally. The calcareous nature 

of all mortar beds, however, indicates that this 

material is less acceptable as riprap for earthen 

dams than siliceous rocks such as silicified chalk 

and quartzite. Before any one mortar bed is accepted 

for this use it is recommended that it be laboratory 

tested for soundness, abrasion loss, and slaking

coefficient. Field experience indicates, too, that 

any one mortar-bed ledge is variable in its test 

properties over relatively short distances.

STRUCTURAL STONE 

ENGINEERING AND GEOLOGIC CHARACTERISTICS

Structural stone, as defined in this report, is 

any hard, dense rock material that can be quarried and 

cut to desired size and shape. Materials fulfilling 

these requirements occur in the Ogallala formation in 

Decatur County.

STRATIGRAPHIC SOURCES AND PERFORMANCE CHARACTERISTICS

Two materials from the Ogallala formation have 

been used as structural stone in Decatur County. The 

Community Building at Jennings was constructed of 

the dense nodular limestone that occurs in the upper 

part of the formation. It was built in 1939, and 

examination in 1947 indicates that it has not weathered 

appreciably nor has it reacted with the cement of the 

mortar. The stone was taken from a quarry in the 

NWi SWi sec. 29, T. 4 S., R. 26 W.

Mortar bed was used in 1938 in the construction 

of a grade school building at Traer. The stone has 

not changed color through weathering, and there is no 

indication of mortar reaction with the rock. On the 

north side of the building, however, some of the stones 

are weathering fairly rapidly, as indicated by excessive pitting of their external surfaces. This probably 

is due to the weathering of the calcareous cement. 

The. stone was quarried in the N Wi SEi sec. 4, T. 2 S., 

R. 30 W.

Field observation indicates that both the mortar 

bed and the dense nodular limeslone are acceptable as 

structural stone. Laboratory testing of all such materials is recommended before the stone is developed 

from any one site. Rapid changes of quality in short 

distances must also be considered.

CALCAREOUS BINDER 

ENGINEERING AND GEOLOGIC CHARACTERISTICS

To be classified as calcareous binder a material 

must be composed essentially of calcium carbonate and 

must be soft an.d easily pulverized.

STRATIGRAPHIC SOURCES AND PERFORMANCE CHARACTERISTICS

Mortar beds of the Ogallala formation in other 

Kansas counties have been accepted by the State Highway 

Commission as calcareous binder. Although no one of 

them in Decatur, County was tested for this use, field 

observation indicates that many of them probably would 

prove acceptable. The mortar beds contain a very high 

percentage of calcium carbonate, and some of them are 

soft enough to be pulverized easily. This material can 

be obtained from practically all parts of the county 

where outcrops of the Ogallala formation are shown.

- 11- iBt»rior Duplicating Seotiw, . ». c.

T*»T1
DEPARTMENT OF THE INTERIOR 

UNITED STATES GEOLOGICAL SURVEY CIRCULAR 40 PLATE 1

R 3O W R 29 W R 28 W R 27 W R 26 W

R 3O W R 29 W R 28 W R 27 W R 26 W

Base adapted from maps provided by 

the State Highway Commission of Kansas. 

Drainage adapted from maps compiled 

by the Soil Conservation Service, U. S. 

Department of Agriculture

MAP SHOWING CONSTRUCTION MATERIALS AND GEOLOGY OF DECATUR COUNTY, KANSAS

Geology by Charles H. Bearman and Claude W. Matthews

Scale

4 Miles

1950

PLATE 1

MAP SHOWING 

CONSTRUCTION MATERIALS AND GEOLOGY

OF

DECATUR COUNTY, KANSAS 

I960

i

s:

EXPLANATION

Alluvium

Tan to dark-brown silt; some clay and silty sand; occasional lenses of gravel. Source or potential source 

of aggregate, and road metal.

Terrace deposits

Tan or gray silt in upper part, often with a buried soil 

zone; occasional sand and gravel lenses in lower part. 

Source or potential source of mineral filler, aggregate, and road metal.

Sanborn formation

Tan or gray silt locally red-brown in basal, part; one 

or more buried soil zones often present; numerous 

calcareous nodules or stringers in "B" zone; columnar structure usually well-developed; local lenses of 

sand and gravel in basal part. Source or potential 

source of mineral filler, aggregate, and road metal.

Ogallala formation

Lenticular ledges of mortar bed interbedded with lenses 

of sand, gravel, and silt; hard nodular limestone 

locally present in upper part; some lenses of volcanic 

ash; basal part locally a brown, gray, green, or maroon clay. Source or potential source of, aggregate, 

road metal, volcanic ash, structural stone, and riprap.

Pierre shale

Thin-bedded dark-gray clay shale; limonite-stained 

along fractures.

Smoky Hill chalk member 

of the Niobrara formation

Beds of brown silicified chalk separated by thin chalky 

shales.

Geologic boundary

Operated pit or quarry

Prospect pit or quarry

7s

Limestone

mb

Mortar bed

fa

Fine aggregate

ma

Mixed aggregate

mf

Mineral filler

.va

Volcanic ash

ma

Inclined letters indicate materials not tested

ma 2

Vertical letters indicate materials listed 

in table 1 and their sample numbers

1.0

Quantity of material available 

(in units of 1O,OOO cubic yards)

Federal US Highways

Other roads, all classes

Railroad

City

Section line

Township corner

Stream, permanent

Stream, intermittent

Lake

B

Line of cross section, figure 3 (along line 

between sees. 32 and 33, T. 3 S., R. 3O W., 

and sec*. 2O and 21, T. 4 S., R. 3O W.)

APPROXIMATE MEAN 

DECLINATION. IB47

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