302 



GEOLOGY. 



H ird Pan. — Gumbo Soil. — One of the peculiar deposits of the 

 State is known among the people as hard pan, and in some places 

 as gumbo soil. It never occurs in this State over extensive areas. 

 In some few counties and townships it occurs in spots — sometimes 

 on bottoms and sometimes on level uplands. The areas covered by 

 it range in extent from a few yards to several acres. Sometimes 

 these spots lie slightly below the general level of the land, and in 

 places shade insensibly into what are known as clay and wet lands. 

 There are, a few townships in the south part of Cedar, Knox, and 

 the north part of Pierce counties where occasional sections occur 

 that have a spotted appearance which is produced by these " gum- 

 bo soils." They are easily recognized by the paucity of the pecu- 

 liar blue and wire grasses that cover them. More rarely they are 

 covered by from two to six inches of alluvium or ordinary upland 

 soil, and only give indications of their presence when an attempt is 

 made at their cultivation. They " bake " and become exceedingly 

 hard when dried. The most compact of these soils are plowed and 

 cultivated with great difficulty. The following analyses indicate 

 their composition. The first is taken from a specimen on Salt 

 Creek bottom, and the second from the lower Nemaha: 



Insoluble (silicious) matter 



Ferric oxide 



Alumina, clay 



Lime carbonate 



Lime phosphate 



Magnesia carbonate 



Potassa 



Soila 



Organic matter 



Moisture 



Loss in analysis 



Total 



No. 1. 



27.11 



20. G7 



4.32 



2 83 



50.11 



57.30 



8.21 



I). 08 



1.09 



.88 



1.45 



1.70 



1 . 1)8 



.(17 



.83 



1.80 



1.30 



2.01 



2 . i>0 



2 0!» 



.70 



.87 



100.00 



100.00 



This analysis shows that these soils contain clay in excess. From 

 many other analyses which I made, only to ascertain the amount 

 of clay that was present, it was found to vary from fifteen to sixty 

 percent. The quantity of all their constituents varies a great deal, 

 but they all in common contain a large amount of clay. A few 

 contained a perceptible quantity of manganese. From these analy- 

 ses it is clear what is needed to redeem them or make them tillable 



