DESCRIPTION AND NAMING OF SEDIMENTARY ROCKS 661 
of sericite needles, microcline much fresher; average size for both, 
0.05mm. Biotite shredded. Muscovite largely secondary, but 
some long twisted primary fibers. 
Classed: granitogene glauconitic-ferruginous fine-grained sand- 
stone. 
Wy 58: Taken at Turkey Creek, + mi. south of Steamboat 
Point, 9 ft. above granite. 
Description of hand specimen: Limestone, 1-in. lenses, reddish- 
brown, coarse-grained; occurring in shale, fissile, paper-thin, green 
with silky luster, trilobitic on bedding-planes (Ptychoparia), 
brachiopods rare. 
Texture granular-fragmental. Constituents calcite 95 per cent; 
small amounts of quartz, magnetite, zircon, siderite as accessories. 
Cement calcite and a trifle limonite. 
Calcite averages 0.75 mm.; often in rods and rectangular blocks, 
obviously fossil fragments, the remaining calcite due to solution and 
redeposition. Within shell fragments a finely comminuted mixture 
of quartz, calcite, siderite; limonite, probably from siderite, out- 
lines fragment edges. Quartz 0.02 to 0.03 mm., angular. 
Classed: coarse-grained brachiopodic limestone. 
Wy 99: Taken at Deer Creek, 1 mi. northwest of Sheep Moun- 
tain, 100 ft. below the persistent sandstone described as Wy 8g. 
Description of hand specimen: Limestone, massive 1-in. bed 
between thick green shales; gray-blue, weathers dirty-brown, 
crossed by veins of calcite; hard, medium-grained, subvitreous 
luster, brachiopodic and trilobitic. 
Texture granular-fragmental. Constituents calcite 90 per cent; 
small amounts of quartz, magnetite, glauconite, pyrite, zircon, 
ilmenite as accessories, and leucoxene as alteration product. 
Calcite 0.35 mm., anhedral; at times within shell fragments and 
then comminuted; ‘“‘rods” clearly from genal spines of trilobites, 
fragments 4 to 5mm. long. Quartz mainly in shells, angular, 
seldom as much as 0.o4mm. Glauconite seemingly developed in 
shells. Much chitinous material. 
Classed: medium-grained brachiopodic trilobitic glauconitic 
limestone. 
