That the mountainous mass of western Maui is much older is shown by the destruction of its crater, by its sharp ridges and by deeply eroded gorges or valleys.
Quarter of the state, and are separated from a lower, greatly eroded highland region on their N.
Corner of Arizona is a region of greatly eroded ranges and gentle aggraded valleys.
At some period, long subsequent to its original excavation, and after many large stalactites had grown, it was completely filled with glacial mud charged with acid, whereby the dripstone was eroded into singularly grotesque shapes.
The most striking feature of the embayment is the broad valley which the Mississippi has eroded across it.