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University of Kansas Geological Survey. 
STRUCTURAL RELATIONS OF TERTIARY MATERIALS. 
The structural relations of the different Tertiary materials are 
far from regular. It is doubtful if there can be any definite strati- 
graphic relations established covering a considerable scope of coun- 
try. A description of the conditions will first be given, and later a 
discussion of the same. 
The gravel and sand are frequently cemented into a moderately 
firm rock by the presence of a variable amount of a calcium car- 
bonate cement. This is sometimes found in the clay as well, but it 
is most abundant in the sand and gravel, producing a sort of sand- 
stone or conglomerate to which the name mortar beds or “grit” is 
generally applied. Some of the varieties of this are the so-called 
‘natural mortar,’ which is extensively used throughout the west 
for making a mortar to plaster with and to roof houses. These 
mortar bed horizons are prominent features in many places, and 
constitute the only hard and resisting strata in the Tertiary. The 
idea so frequently expressed that they are located near the base of 
the Tertiary is correct for some localities, but incorrect for others. 
Hvidence from Surface Conditions.—Along the Prairie Dog from 
near its source to the eastern limits of the Tertiary the mortar beds 
are frequently found, often in a high degree of development. They 
frequently lie near the tops of the hills. On the south bank of the 
stream at Clayton they furnish two well defined horizons, ‘the 
uppermost one near the top of the hill, and often 20 or 30 feet thick. 
Below these we have 20 or 30 feet of clay and sand which is poorly 
cemented, and then the second mortar beds horizon which will 
average 20 feet or more in thickness. There is so much difference 
between the hard and soft layers that weathering has given the 
bluffs a terraced appearance. The mortar bed layers contain much 
gravel and ordinary sand. The exact distance below them to the 
base of the Tertiary is not known, but it must be 50 feet or more. 
On the high divides both north and south of Stockton, in Rooks 
county, the Tertiary covers the country. The very summits of the 
highest hills are capped with the mortar beds which in this locality, 
particularly to the north of Stockton, is cemented with a silicious 
cement until the rock has been changed almost into a quartzite. The 
