Models of a young earth and models of an old earth both make predictions about what should be seen in geology to support their models. The young-earth creation model states that most of the sedimentary rock layers we see now were laid down quickly during or following (as a result of) the Flood of Noah's time. In support of this, the model predicts first, that there should be evidence of rapid burial and sediment deposition. Second, since the sedimentary layers were deposited very rapidly, they would be in a soft, plastic form, capable of being bent or deformed for some time.

Old-earth models states that the sedimentary rock layers were laid down either very slowly over millions of years (uniformitarianism), or by many catastrophes that were separated by millions of years (neo-catastrophism). In support of this claim, the model predicts first, that there should be evidence of gradual sediment deposition and erosion. Second, since each rock layer took millions of years to deposit, the rock layers on the bottom would be hard, brittle rock when the layer on top was deposited. When deformation of strata occurred the rocks should have been brittle and broken.