Check all that apply. to correctly "read" rocks geologists need to keep which rules in
mind when studying layers of sedimentary rock?
sediments spread out in all directions until they either thin out or run into a barrier

To read the rocks the geologists need to be aware of several things and rules.

They must keep in mind that older rocks are always in the bottom area. The younger rocks keep on getting deposited on the upper layer of the older rocks.

The other rule is that the sedimentary rocks are usually deposited in the horizontal layer directions.  

The spreading out of the sedimentary rocks are in all directions possible unless it gets thin out or until it runs into a barrier.

answer: land bridge theory. land bridge theory held that shifting portions of dry land explained the finding of identical species on different continents. plate tectonic theory eventually eliminated the land bridge theory.