74 SIDNEY POWERS 
grooved sandstones and casts of branching and interlacing stems 
generally admitted to represent algae are very common in the 
Osage rocks. Some of the slabs in the New York State Museum 
(Figs. 4, 5) show markings which, in the opinion of the writer, 
were formed as impressions of either algae, or of wood and nodes of 
plants. In some cases they show faint striations like the plant 
impressions of the same size on the Joggins section, Nova Scotia, 
or in the North Sydney section, Cape Breton Island (plates 18 
and 22 of Clarke). In other cases the rounded elevations (filling 
Fic. 6.—Blocks of sandstone in which are casts of V-shaped grooves and which 
are themselves grooved with sinuous lines. The plaster cast at the left shows the 
original. A branch or root dragged over fine-grained argillaceous sand could produce 
such grooves. Locality, Strawn, Texas. The block of sandstone at the top shows 
somewhat comparable markings produced by weathering of cross-bedding. Locality, 
basal Eocene, southeast of Uvalde, Texas. 
of depressions in the original strand surface) may be partly broken 
from the rock (Fig. 5), showing that they had an upper as well 
as a lower surface and may represent casts of kelplike material. 
In the Tesnus formation of Pennsylvanian (Pottsville) age, 9 miles 
south of Marathon, Texas, and 225 feet below the top of the 
formation, there is a heavy sandstone bed showing mud flow 
and ripple marks and plant casts, but no groovings. 
