Breccia Pipe Anatomy The Northern Arizona plateau region is host
to thousands of breccia pipes. Breccia pipes are vertical or
near vertical, circular to elliptical bodies of broken rock. The
broken rock is comprised of slabs and rotated angular blocks and
fragments of surrounding and stratigraphically higher
formations. Hence, many geologists consider the pipes to have
been formed by solution collapse of the underlying Redwall
Limestone. Surrounding the blocks and slabs making up the
breccia is a matrix of fine material comprised of surrounding
and overlying rock from various formations. The matrix has
mostly been cemented by silicification and calcification. The
roots of a breccia pipe start within the Mississippian Redwall
Limestone and extend up to 3000 ft vertically through various
rock strata of the Colorado Plateau in northwestern Arizona.
Dissolution of the Redwall Limestone about 330 million years ago
formed numerous caves in this thick limestone layer. When the
cave roof collapsed, overlying formatio