disturbed from the time of their deposition. 
Among the examples of this kind may be noticed more sip 
one between Davenport and Le Claire, Within three miles ) 
the latter place the strata of upper Silurian limestones dip to os 
northward, and between two points of outcrop, the horizon 
hada of coal shales, sandstones and iron ore, occupy the space, 
us: 
7 . b . 
the northeast. 
3, 6, coal shal d 
In another instance the coal measures present the following ng 
relations to the underlying rocks: iste ss ee 
‘ 24 ae 
Se 
4, a, axis of Silurian limestone. poe with 
4, horizontal coal measure strata traced to within three feet of actual contact with the 
limestones which dip at an angle of 30°. 
