126 University Geological Survey of Kansas. 
lying as regular in direction and extent as such local con- 
tractions would require. Occasionally by this shrinkage 
slight tangential contractional tendencies might be produced 
and the small amount of ‘‘slicken sides’’ phenomena readily 
accounted for. 
Third.—Ascending waters, to whatever extent they occur, 
may have brought with them some lead ore and zinc ore and 
may have concentrated the same in the fissures. But a much 
larger amount of ore probably was concentrated from the over- 
lying Coal Measure formations gradually removed by surface 
erosion, during which time surface descending waters worked 
their way downward into the fissures within the Burlington 
limestone and flint. This oft-repeated surface enrichment by 
processes so thoroughly explained by Van Hise, Weed, Em- 
mons, and others, and now so well understood and univer- 
sally accepted by geologists, probably has been the main 
agency for the accumulation of great and almost unparalleled 
bodies of zinc ore and lead ore in the Galena-Joplin district. 
