The Pre-Cambrian Structure of Missouri 151 
East of the Proctor anticline, there is a. broad, anticline 
extending northwest through the southeastern part of Morgan 
County (30). East of this area in Miller County, a small anti- 
cline crosses the Osage River southwest of Tuscumbia (1). The 
Osage flows east along the side of this anticline for about four 
miles. South of Tuscumbia there is a small dome. To the east 
another anticline crosses the river and on the south side of this 
anticline there is a small dome. West of. St. Elizabeth, the 
river turns north along the axis of an anticline. 
Granite boulders occur along the Osage River on the north- 
east trending stretch near Tuscumbia and another boulder is 
located at the bend of the river near Henley (1). These boul- 
ders have been thought to be of glacial origin, either directly 
transported or ice-rafted. They are smooth but show no striz. 
The location of these boulders on the crests of anticlines may 
be in indication that they are derived from the underlying pre- 
Cambrian rather than being erratics. The Decaturville Dome 
was located by the presence of igneous boulders before the peg- 
Matite was seen in place. Simliar boulders in northern Moniteau 
County (48) are probably erratics for here they lie on the Jef- 
ferson City formation with no indication of any uplift in the 
Ocality, 
Pike County uplift. Along the Mississippi River, north of 
the Missouri River, there is an area of Ordovician rocks elongat- 
ed in a northwest—southeast direction as shown in Plate I. This 
area extends from the Cap au Gres fault in Lincoln County north- 
west through Pike County into Ralls County. The Lincoln fold 
and Cap au Gres fault strike about N. 70° W., but turn at the west 
end to strike N, 20° W.(29). ‘The axis of a fold continues the 
northwest trend throughout the area discussed. The difference in 
trend of the present structure with the outcrops of Ordovician 
rocks suggests that the Ordovician rocks owe their elevation to 
uplift before folding. This may be the result of movement along 
Pre-Cambrian structures in late Ordovician time, followed by 
Post-Pennsylvanian folding. The northwest—southeast struc- 
