WATER-WORN COAL PEBBLES IN CARBONIFEROUS 
SANDSTONE 
WILLIAM F. PROUTY 
Geological Survey of Alabama 
The accompanying photograph illustrates rounded pebbles of 
bituminous coal, one of which is shown imbedded in a coarse- 
grained sandstone. These pebbles are exposed in large numbers 
in a stone quarry which is located’ on the banks of the Warrior 
River just above Lock No. 12, Tuscaloosa, Ala., and but a short 
distance from the State University. The sandstone is in some 
places very coarse and conglomeratic. In many cases the coarse 
fragments making the conglomerate are angular, having received 
but little wear. At the locality where the coal pebbles occur most 
numerously there is much cross-bedding of the sandstone and a 
marked difference in the coarseness and fineness of the sediment 
together with considerable contemporaneous erosion, thus giving 
evidence of a delta deposit. In the sandstone which carries the 
coal pebbles are found many fragments of carboniferous trees. 
The geological position of this sandstone is near the top of the coal 
measures of the Warrior Coal Field, being about 60 feet above 
the Duree coal seam and about 30 feet below the Brookwood 
coal seam of the Brookwood group (the highest known group of 
coals in the Warrior field). The size of the pebbles varies from 
y-inch to 15 inches or more in diameter. One pebble observed 
had the shape of a prolate spheroid about 18 inches long and 
nearly 12 inches thick. This was imbedded in a coarse-grained 
sandstone. 
An analysis of the coal, from the pebble shown in the photo- 
graph imbedded in the rock, is as follows: 
MOIS FUT eneeienan tok scien ea eae c 2.42 
Wolatilesmatter.s war. neice eu teectoe a cokes 20n72 
xe dscarbomeacwsnca ge cese saree ee re le 56.06 
Ja) DRI IS eA Ore enter Rn ot eg Sa 2.79 
100.00 
tThe occurrence of coal pebbles at this locality was first called to my attention 
by Dr. E. A. Smith of the University of Alabama. 
769 
