290 
PETER SANDSTONE 
well-bedded and ripple-marked, and is entirely indistinguishable 
on the basis of size of grain, purity, or degree of rounding, from 
the Peter sandstones above. The Everton limestone member, 
which is also quite variable in thickness, yields marine fossils in 
Arkansas. The total thickness of the Everton terrane in Mis¬ 
souri varies from less than 30 to over 75 feet. Traced northward, 
the Everton limestone thins out at the Missouri river, allowing 
the Everton and Peter sandstones to come together. Under these 
conditions they are wholly indistinguishable, and it is only on the 
basis of total thickness that both are believed to be represented 
north of this line. The Everton division is known to occur on 
the south flank of the Ozarks in Arkansas, and on their east 
flank in Missouri; but it is not known on the west flank. 
Some slight emergence and erosion, probably greater to the 
south, than to the north, appeared to have taken place between Ev¬ 
erton beds and the typical Peter sandstone. The Peter division, 
like the Everton, is not known in outcrop on the west flank of 
the Ozarks and its recognition in deep-well records is open to 
grave doubt. When the Everton beds are present, the Peter 
division varies from over 65 to 35 feet, and, north of any known 
Everton beds, averages 100 feet, a fact indicating the probable 
inclusion of the Everton sandstone (the limestone having failed) 
in the so-called Peter section. In southeast Missouri, and prob¬ 
ably also in Arkansas, the Peter sandstone carries limestone lenses, 
and marine fossils were found at one point at the junction line 
between it and the overlying Joachim dolomites. Limestone lenses 
are also reported in north Missouri, in Iowa, and in Illinois, in 
deep-well records. Marine fossils are reported by Sardeson at 
three horizons, well down in the formation, near Minneapolis. 
The unconformity at the base of the Peter sandstone in the 
northern states is undoubtedly the same as that at the base of the 
Everton beds in Missouri. The line marked in Missouri by not¬ 
able relief, basal conglomerates, and residual soils, and similar 
phenomena are reported in Iowa and Wisconsin, the stratigraphic 
hiatus, and probably the time-value, increasing northward. 
The degree of rounding of Peter sand-grains is comparable 
to that displayed in the Roubidoux sandstone, and in the sand¬ 
stone lenses of the Jefferson and Cotter dolomites; as are also 
the size of grain, uniformity of grain, and degree of purity. The 
