Red Clay:

 I have been gone from the South so long I had totally forgotten about "red clay". That clay when it is wet is like ice {very slippery} and sticks to your shoes forming a concrete consistency attachment. 

"The composition of the rock determines the color of the clay. In the case of the red clay found here, iron oxides provide the deep red hue. Iron oxide is a fancy term for rust. The more iron in the clay, the redder it is". 

I suddenly remembered red clay when I went down to the basement following a rain storm. I suddenly grew another 1/2 inch collecting red clay on the bottom of my shoes and had to hold onto things to keep my feet from slipping out from under me.