The sediments are the sedimentary rock layers all over the world.
The Evolution model requires various high lying areas like Colorado, Montana, North Dakota, Africa, etc. (1 mile above sea level) to be covered in "shallow seas" in order to lay down the expansively enormous and deep sedementary layers that are readily apparent to the naked eye (Grand Canyon, Badlands, Great Rift Valley, Sideling Hill Cut, etc.).
There is another name for highlands being covered in shallow seas - Noah's Flood. Evolutionists just aren't honest enough to admit that their model requires the same sort of widespread flooding that the Biblical Noah account does.
ALL of them? There are all kinds of non-flood sediments. There's the normal slow accumulation of silt in swamplands. There is windblown dust and sand. There is slow silting of lake and sea bottoms. Many of these types of sedimentation leave fossilized signatures of tranquil surface conditions which cannot occur in flood sediments.
Now, we do see flood sediments in the geologic column. They have a certain signature. Most of the geologic column in any given place tends to be non-flood. And the floods we do see are regional events only.
That's the For Dummies summary. For a more comprehensive list of what's wrong with your hopelessly naive formulation, peruse Flood Predictions.
The Evolution model requires various high lying areas like Colorado, Montana, North Dakota, Africa, etc. (1 mile above sea level) to be covered in "shallow seas" in order to lay down the expansively enormous and deep sedementary layers that are readily apparent to the naked eye (Grand Canyon, Badlands, Great Rift Valley, Sideling Hill Cut, etc.).
For starters, it is geology, not evolution, which describes the layering of the geologic column. This is worth straightening out because many of you will say something like, "I love science, I just don't accept evolution." Then it turns out the speaker does not accept geology, astronomy, cosmology, nuclear chemistry, or anything else in science that is used to support an old Earth or an old universe.
Geology says that sedimentary layers do not get deposited on preexisting mountains. There is no way to do this and not just because it is impractical to cover the mountain with water. Even if you somehow deposit something on the mountain, it will just erode away. That's what mountains do. They wear down.
So you don't even understand what geology says about sediment layers on mountains. Well, sedimentary layers in mountains ARE the mountain. They used to lie flat and then they got warped. There are mountains that aren't sedimentary in character. They're called "volcanoes." They have a different structure entirely and they don't have any fossiliferous sediments on them. The sedimentary mountains are sediments to a great depth. When they were made, the layers crumpled both up AND DOWN. The lithosphere is thickened under mountains because the crushing displaces the warped crust in both directions. In fact, sort of like an iceberg, there's more below than above.
So you have two problems: 1) Your version is impossible, and 2) you have no understanding of the mainstream version.