Dating rock strata
For example, the kind of sediment in a particular stratum tells geologists something about how the sediment was deposited, and where.
Sandstone forms from beach, floodplain or delta sand deposits, while limestone is made of the shell fragments of ocean-dwelling organisms that collected on a seafloor.
Sedimentary strata can even be found atop mountain ranges, where rock layers have been lifted thousands of feet.
While it is possible for layering to form in other rocks, it is the singular feature of sedimentary rocks.
Those are clouds that are spread out in layers, but are not all that thick vertically.
Well, rock strata are pretty much the same thing - except they aren't clouds, they aren't in the sky, and they're made of sediment and not water droplets.
Strata are very important geologic features because geologists can use them to construct interpretations of the sequence of geologic events that happened far in the past.
As it turns out, rock strata are present almost everywhere.
That's because the processes that create them are acting on the earth's surface.
Because we know that sediment is originally deposited in flat-lying layers, if rock strata are tilted or offset by a fault, it means there has been tectonic activity in an area.
Geologists also use sequences of rock strata to determine the ages of different beds relative to one another.
Geologists tend to use the term 'rock strata' in a generic sense when referring to many rock layers that appear over large areas.