74 University Geological Survey of Kansas. 
ties is the large amount of iron sulphate present in the well 
water whenever the wells have penetrated into the undecom- 
posed shales. 
The presence of such gypsum is interesting principally from 
theoretical considerations, illustrating, as it does in a beautiful 
manner, one of the possible modes by which gypsum may be 
formed. 
GYPSUM IN THE CRETACEOUS SHALES. 
In many parts of the state, where the different Cretaceous 
shale beds are exposed to the surface, fine crystals of gypsum 
are frequently found. Along the Smoky Hill river, in Ells- 
worth and McPherson counties, such crystals are particularly 
numerous. Some of them measure from three to four.inches in 
length, and are magnificent museum specimens of well formed 
crystallized gypsum. They do not occur in sufficient abun- 
dance to be of any importance for manufacturing purposes. 
The origin of such gypsum is not readily apparent. It may 
be similar to that above described for the Coal Measure shales, 
but the evidence in favor of if is not so strongly marked here. 
Another possible explanation of it is the leaching out of the 
small quantities of gypsum originally included in these shales 
and the concentration of the same at or near the surface where 
such waters evaporate. A third, but less probable, origin is 
that of a crystallization of gypsum crystals from the ocean wa- 
ter in which the shales were formed. At any rate, some of the 
finest museum specimens of crystallized gypsum known to the 
writer have been found in these localities. 
GYPSUM IN THE TERTIARY FORMATIONS. 
In the southwestern part of the state where the Tertiary forma- . 
tions come immediately in contact with the Red Beds, the 
lowermost portions of the Tertiary sands are frequently filled 
with well formed gypsum crystals. This is particularly true in 
the southwestern part of Meade county and in different places 
in Seward county. Here for a distance of from 50 to 100 feet 
above the contact line between the Red Beds and the Tertiary, 
gypsum crystals are abundant, formed as perfectly as any known 
