Cathedral Gorge State Park Nevada (picts 5-7), is an amazing modern(ish) analog to help us see how Bryce Canyon National Park (picts 1-3) formed.
The layers of Bryce Canyon were deposited between ~40 & 63 million years ago (mya). They are nearly devoid of fossils which makes definitively identifying its deposition environment difficult. Some argue for shallow lake systems, mixed with broad flood plains while others argue that shallow lakes were not needed to form the lenses of limestone and marl between the clays.
Cathedral Gorge State Park looks visually and geologically VERY similar to Bryce. But its layers were deposited a mere 1-3 million years ago. The young age, and abundance of rodent fossils makes identifying the fluvial nature of the layers MUCH easier. If small, water-filled playas were involved in the deposition of these mudstones, limestones, and marls they were seasonal and very shallow.
By studying the canyons, caves, and corridors of the geologically young Cathedral Gorge, we can be more confident in suggesting that the layers of Bryce Canyon formed in much the same way, and know that the paucity of fossils is likely due to the fact that dinosaurs had just gone extinct and burrowing mammals were rare and in the early stages of evolving...