Marsh systems allowed people in some parts of Utah to live in year-round settlements adjacent to the marshes. It is illegal to collect artifacts from sites on Federal or State lands. It is illegal to take anything from private land without the permission of the landowner. Removing artifacts from sites disrupts the archaeological record because the artifact is removed from its context. Collecting sites is a huge problem in Utah.
Some archaeological sites are no longer visible because all of the artifacts have been collected.
No, archaeologists deal only with material left by human beings. Paleontologists are the scientists who study dinosaurs and fossils. I get this question almost every time I visit a school. I use this as an opportunity to talk about other things archaeologists are interested in besides the artifacts. I use an example of pinyon pine charcoal from fire-pits 6000 years old in Colorado where currently there are no pinyon pine trees.