360 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213. 
fourths of a mile east of the Chicago and Western Indiana Railroad 
the rock is rather thinly covered in the hill slope. Three and one-half 
miles south of Elmhurst rock can be obtained in the west bank of Salt 
Creek. Abundant rock is thinly covered south and east of Lyons; 
also down Desplaines Valley from McCook, along the north side of 
the river. At Sag Bridge and at Leinont abundant rock is easily 
quarried. The southwestern part of the area is most poorly supplied, 
though the proximity of Joliet may counterbalance this deficiency. 
Only two exposures were noted in this part of the area, one 5 miles 
east of Orland, along the banks of a small creek; the other along the 
bed of Hickory Creek, near New Lenox. 
Where the bituminous limestone has been used for building pur- 
poses the staining gives a peculiarly venerable appearance to the 
structure. There is, however, the disadvantage that the melting and 
running out of the bitumen may give a disagreeable streaking to the 
walls. 
The abundant drift bowlders of limestone, sandstone, igneous and 
metamorphic rocks have furnished material for many picturesque 
and beautiful buildings within the district and could supply a further 
demand. These are also of value in the construction of piers and 
breakwaters. 
SAND AND GRAVEL. 
The wide distribution of sand and gravel over the Chicago Plain 
has afforded abundant material for building sand, roofing and road 
gravels, and for filling. The extensive deposits of dune sand along 
the present lake shore, along the west side of the Blue Island ridge, 
southwest and south of Hammond, Ind., and east of Thornton, furnish 
abundant fine, clean sand. The deposits of glacial gravel furnish 
the coarser gravels, with some sand and fine gravel. Several large 
pits have been opened about a mile north of Willow Springs, in the 
north slope of Desplaines Valley. The deposits here are assorted into 
several grades of gravel for building, paving, and ballast purposes. 
The output at these pits is 20 to 25 carloads per day. Numerous pits 
have been opened at various points along Desplaines Valley, showing 
material grading from sand and gravel to very stony till, composed 
almost entirely of well-*worn limestone pebbles and bowlders. In 
places this limestone is partially cemented into a conglomerate, so as 
to come out in large masses. One-half mile southwest of Worth 
Messrs. Henke & Read have opened a large gravel pit. The gravels 
here are assorted into grades of two sizes. Ten to twelve thousand 
cubic yards have been taken out per annum. At Blue Island, just 
north of the Chicago, Rock Island and Pacific Railway station, there 
is an extensive deposit of the coarser beach gravel. The entire south 
end of the ridge seems to be composed of these gravels. 
