Life is more exciting when one treads away from the everyday path, seeking bold new horizons.
Between these are structurally weaker palaeosol horizons of weathered basalt that encourage localized collapse as the wear back and undermine the overlying basalt.
There is considerable difference of opinion as to the chronology of the succeeding beds, and the boundary between the Cretaceous and Tertiary systems is drawn at various horizons by different observers.
The igneous rocks occur at several geological horizons, but the great volcanic eruptions did not begin until the Tertiary period.
Hatcher, demonstrate the Pleistocene nature of the deposits, by which is not necessarily meant older Quaternary, for their horizons have not been differentiated and correlated in South America.