Note 6 — Chapter IV
Reading edition
It is not here asserted that these notches were as deep as now, in pre-Cambrian time. It is, however, certain that the quartzite was deeply eroded, previous to the deposition of the Potsdam sandstone.
Reading edition
It is not here asserted that these notches were as deep as now, in pre-Cambrian time. It is, however, certain that the quartzite was deeply eroded, previous to the deposition of the Potsdam sandstone.