OF THE UPPER MISSOURI, 49 
Crinoid columns : large tabular masses of this rock were strewed along the slope for some 
distance below. 
At the mouth of the Big Blue river, on the south side of the Kansas, there is an abrupt 
bluff, along which several slides have exposed many of the beds composing the high ridge 
mentioned six or seven miles below here. The dip, however, of the strata towards the 
west or northwest is so great that the limestone containing spines of Archwociduris, seen 
on the summit of the ridge below this, at an elevation of about 320 feet above the Kansas, 
is here, opposite the mouth of the Big Blue river, only elevated about 214 feet above the 
Kansas ; consequently the three feet of grayish yellow limestone cropping out 115 feet 
above the Kansas along the slope of the ridge above mentioned, at the mouth of the Blue 
river, has sunk beneath the level of the Kansas. 
This far we have scarcely attempted to draw parallels between the various beds seen by 
us at different places, in consequence of the fact that our observations were isolated, as 
must necessarily be the case in a mere reconnoissance, extended over a large area in a 
short space of time. In addition to this, the group of rocks examined presents no exten- 
sive beds of limestone or other hard material, forming well-marked horizons, or continuous 
lines of outcrop, by which the relations between strata seen at different localities could be 
traced out. ‘This difficulty is also greatly increased by the frequent repetition of precisely 
similar beds at different horizons in the series, and above all by the great vertical range of 
the organic remains. Consequently we have preferred to present separately the local sec- 
tions examined, instead of attempting to construct a continuous general vertical section 
showing the order of superposition of the various strata. ‘To do this successfully through- 
out all the various rocks of the whole Kansas valley would require much more time than 
we had at our command. 
As our examinations along the Kansas and Smoky Hill rivers above this point were 
made in more detail, where the outcrops were more frequent and continuous, we have, as 
we believe, been able to trace out the connections and order of succession of the various 
strata with considerable accuracy. Hence, we give below a general section of the rocks 
in this region, commencing with the Cretaceous sandstones on the summits of the Smoky 
hills, lat. 38° 30’ N., long. 98° W., and descending through the various intermediate for- 
mations seen along the Smoky Hill and Kansas rivers, to the base of the bluff already 
mentioned, opposite the mouth of Big Blue river, on the Kansas. It is true, there are a 
few gaps in this section, where we were unable to see the beds along some of the slopes, 
but as we know the position in the series, as well as the extent of these gaps, it will be 
easy to determine, when a greater number of exposures have been examined, the nature 
of the beds occupying them. 
VOL. Xt.—/ 
