If so, each pair of sediment layers represents an annual deposit . . . . The total number of varve pairs indicates that the lakes existed for a few million years. As long ago as 1961, creationists were pointing out features of the Green River Formation that were difficult to reconcile with the conventional varve interpretation. For instance, well-preserved fossils are abundant and widespread throughout the sediments. The catfish range in length from 11 to 24 cm, with a mean of 18 cm.
Preservation is excellent.
Modern-day lakes do not provide the conditions needed for the preservation of abundant fossil fish and birds. Experiments by scientists from the Chicago Natural History Museum have shown that fish carcasses lowered on to the muddy bottom of a marsh decay quite rapidly, even in oxygen-poor conditions. The Presbyornis fossils are even more problematic. Birds have hollow bones that tend not to preserve well in the fossil record. Enormous concentrations' of bird bones are a clear indication that something is seriously wrong with the idea of slow accumulation.