76 SIDNEY POWERS 
beautifully exhibited in slabs forming pillars at the south entrance 
to the Tulsa Country Club (Tulsa, Oklahoma) characteristically 
are superimposed, and have the same diameter as the supposed 
crystal tubes. It is barely possible that climatic conditions in the 
several geologic periods in which these markings were formed were 
such that ground ice and ice crystals could form. 
2. Dragging of parts of trees or roots of algae or of pebbles over 
the strand.—Groovings in sandy clay may be produced by shoving 
or dragging objects over the surface either above or below water. 
The alga, Ulva enteromorpha, has been observed dragging pebbles 
over the strand making depressions.t_ Ulva grows in tufts 6 to 8 
inches high attached to one side of pebbles as large as 2 inch in 
diameter. The fronds stand upright from the anchoring pebble, 
and wave back and forth dragging the pebble, but not lifting it. 
Either single or double grooves are produced, and the grooves in 
the illustrations cannot be distinguished from many of the single 
Osage grooves. One can readily imagine how this operation could 
produce many of the irregular Osage markings, especially those 
which cross (Fig. 3), but pebbles are very rare in the Osage 
sediments.? To produce parallel groovings bunches of large algae 
could be washed along by the tide, and where the algae came to 
rest irregular depressions would be produced in the sandy shale 
as stated above. Curves in the grooves, especially in some and 
not in others, could readily be produced by obstructions in the 
path of the algae (Fig. 2, upper corner) or by swirls in the tidal 
action, or by undertow. 
Fragments of fossil wood indicate the presence of trees at the 
same horizon as the parallel markings. Were a log washed over 
the strand it would normally rotate; were a stump dragged along 
some of the roots would make deep, sharp-pointed grooves and 
ridges such as are occasionally found alone (Fig. 6). A log 
could not make the curved and diverging markings, but light 
pieces of wood could produce superimposed series of striations. 
Single grooves with finely striated sides unassociated with other 
tA. P. Brown, “The Formation of Ripple Marks, Tracks, and Trails,” Proc. 
Acad. Nat. Sci., Philadelphia, Vol. LXIII (1911), pp. 536-47. 
2C. S$. Ross reports a conglomeratic limestone in the south part of T. 22 N., 
R. 7 E., that contains gravels and small pebbles of white vein quartz, igneous, and 
metamorphic rocks which were possibly carried by floating ice. 
