Measured By H. Miller and E. Gutentag; Niobrara,Hard, yellow chalk,Bentonite,Yellow chalk,Bentonite,Yellow chalk,Bentonite,Yellow chalk,Yellow chalk with calcite fills in fissures,Gypsum,Yellow chalk,Limonite and bentonite; gypsum,Yellow chalk,Limonite and bentonite; gypsum,Gray and yellow chalk,Bentonite and gypsum xls,Gray chalk,Bentonite; gypsum xls,Gray chalk,Bentonite and limonite; gypsum xls,Gray chalk, partly covered,