Types of shell hash limestone (labeled) in conglomerate and limestone unit

The heavy dashed line marks the contact between the conglomerate
and limestone unit at the top of the Bandera Formation and the
calcareous shale unit at the base of the Lake Neosho Shale Member
of the Altamont Formation. The upper part of the conglomerate and
limestone unit includes two kinds of shell hash limestone, both
lenticular. The micritic shell hash limestone (arrow) forms very thin and
discontinuous lenses that are interlaminated with shale. The clayey
shell hash limestone occurs in thicker and more extensive lenses at
the top of the conglomerate and limestone unit; note that it pinches
out to the right in this photograph. It has non-calcareous clay matrix
and slakes in water where not cemented by iron oxide, freeing the
shells.

Return to Technical Discussion

Main Menu