How can a lack of erosion undermine evolutionary ideas of long ages of earth history? Well, when geologists study the boundary between two rock layers, they sometimes conclude that there was a significant time gap between when the lower and upper rock layers were laid down.
However, many boundaries don’t show any evidence of elapsed time. The Grand Canyon provides startling examples. One is where the Coconino Sandstone overlies the Hermit Shale. The surface between these rock layers is remarkably flat and smooth—a ‘flat gap’. Yet according to conventional geology, there is a 6 million year gap between these rock layers. The underlying shale is a soft rock, so it should have eroded a lot if exposed for this time. But the Hermit Shale doesn’t show this erosion. This shows that the upper sandstone was deposited on the lower shale so quickly that there was not time for erosion of the shale. Something is obviously wrong with the conventional geological timescale.