DESCRIPTION AND NAMING OF SEDIMENTARY ROCKS 665 
Description of hand specimen: Limestone, 4- to 6-in. beds, 
gray-green, weathering light buff with yellow stains, hard, fine- 
grained, slightly dolomitic, argillaceous, dull luster, lower beds 
much jointed, causing weathering in subquadrate slabs; flat-spired 
gastropods abundant. | 
Texture granular-fragmental. Constituents calcite 99 per cent; 
a little accessory glauconite, limonite as alteration product. Cement 
calcite. | 
Calcite grains often recrystallized, largest 0.3 mm. and appar- 
ently cavity-filling. 
Classed: gastropodic medium-grained limestone; traces of 
glauconite. 
Wy 69: Same locality as Wy 2, 2 ft. below Cambrian-Ordovician- 
contact. 
Description of hand specimen: Conglomerate, massive, greenish- 
gray; pebbles limestone, distinguishable with difficulty on weath- 
ered surface, greenish, subsoft, fine-grained, glauconitic, flattened, 
elongated, length { in. to 2 in., often loose ochreous earth, lining 
cavities, when fresh breaking with matrix, and usually aligned in 
parallel planes, constituting 50 per cent of rock; matrix limestone, 
greenish, fine-grained, dull luster. (This is the famous flat-pebble 
conglomerate of Dakota and Wyoming.) 
Texture conglomeratic. Constituents calcite go per cent; small 
amounts of glauconite, quartz, pyrite, magnetite as accessories, and 
hematite and limonite as alteration products. Cement calcite. 
Calcite either as pebbles, merely fragmentary in slide, or as 
interlocked crystals in matrix. Pebbles characterized by calcite, 
criss-crossed and specked with glauconite (percentage from 25 to 
333), and interlocked with quartz grains below 0.01 mm. diameter. 
Quartz very rare in matrix. Pyrite altering to hematite and 
limonite. 
Classed: glauconitic flat-pebble limestone-conglomerate. 
Wy 24: Same locality as Wy 23, 20 ft. below Cambrian- 
Ordovician contact. 
Description of hand specimen: Seemingly sandstone (and so 
described by one observer), massive, pink, weathering fainter pink. 
