78 SIDNEY POWERS 
ice floated or were dragged around. Some of the irregularities 
(largely sharp ridges and elevations in the original) might have been 
formed by the melting of ice around mud-filled cracks. There 
was no regional Pennsylvanian glaciation in the Osage, for tillites 
have not been found. Bowlders of large size which have been 
interpreted as indicating the presence of floating ice during the 
early Pennsylvanian (Pottsville) in the vicinity of the Arbuckle 
and Ouachita mountains has caused considerable discussion.? 
Recently Professor Samuel Weidman has found striated pebbles in 
the Franks conglomerate of the Arbuckle Mountains together with 
the striated floor of older rocks on which the conglomerate rests.? 
This conglomerate is much older than the sediments of the Osage. 
Another reported locality of tillite near Shafter, Presidio County, 
Texas, has been examined by the writer and is believed by him 
not to be tillite. 
Opposed to the theory of floating ice is the fact that nowhere 
are any of the striated sandstone beds gouged or beveled obliquely 
to the bedding planes; nor are the latter in any way disturbed. 
The varied and complex strand markings, which are much more 
abundant than the grooves on the various blocks of sandstone 
at the same locality, have never been rubbed by ice. 
4. Differential slipping of beds before consolidation.—Slipping 
in unconsolidated beds, especially in muds and silts, is a well- 
known phenomenon recently emphasized in the mud lumps of the 
Mississippi deltat and in experiments by Dr. Kindle.’ ‘The latter 
tJ. A. Taff, “Ice-borne Boulder Deposits in Mid-Carboniferous Marine Shales,” 
Bull. Geol. Soc. Amer., Vol. XX (1909), pp. 701-2; Science (New Series, Vol. XXI 
(1905), p. 225; E. O. Ulrich, ‘Revision of the Paleozoic Systems,” Bull. Geol. Soc. 
Amer., Vol. XXII (1911), p. 352, footnote; J. B. Woodworth, op. cit. 
2 ‘The Probability of Pennsylvanian Glaciation of the Arbuckle Mountain Re- 
gion,”? Bull. Geol. Soc. Amer., Vol. XXXII (1921). 
3 J. A. Udden, “The Geology of the Shafter Silver Mine District, Presidio County, 
Texas,” Univ. of Texas Mineral Survey, Bull. 8 (1904), pp. 14, 59. The only conglom- 
erates found by the writer are at the base of the Cieneguita series as determined by 
the intrusive contact with syenite porphyry. They are very fine conglomerates 
and sandstones composed of rounded quartz pebbles and grains which look like 
fragments of vein quartz rounded by long water erosion. 
4E. W. Shaw, ‘‘The Mud Lumps at the Mouths of the HUSSISSPPE. Wise 
Geol. Survey, Prof. Paper 85b (1914), pp. 11-27. 
s E. M. Kindle, “‘ Deformation of Unconsolidated Beds in Nova Scotia and South- 
ern Ontario,” Bull. Geol. Soc. Amer., Vol. XXVIII (1917), pp. 323-34- 
