Over millions of years, the situation changes. The land rises and falls. Growing mountains make layers tilt. The seas come in and the seas go out. This leads to different sources for the material in the sediments. Silt on a river bottom looks different from sand on a beach. I noted already that volcanic layers in testify to volcanic eruptions at particular times. I'm not a geologist, but the Wikipedia page on the
Geology of the Grand Canyon has a huge amount of information about all the specific layers. Just a random sample:
Metamorphic and igneous basement
ash,
mud,
sand, and
silt were laid down in a shallow marine basin adjacent to an
orogenic belt
Grand Canyon Supergroup
The oldest section of the supergroup is the
Unkar Group. It accumulated in a variety of fluvial, deltaic, tidal, nearshore marine, and offshore marine environments
the
Cardenas Basalt is the youngest formation in the Unkar Group.
[16] It is made of layers of dark brown
basaltic rocks that flowed as
lava up to 1,000 feet (300 m) thick
Tapeats Sandstone averages 525 million years old and is made of medium- to coarse-grained sand and conglomerate that was deposited on an ancient shore
Redwall is composed of thick-bedded, dark brown to bluish gray limestone and dolomite with white
chert nodules mixed in.
[32] It was laid down in a retreating shallow
tropical sea near the equator
Supai Group formations in the western part of the canyon contain limestone, indicative of a warm, shallow sea, while the eastern part was likely a muddy river delta
Coconino Sandstone formed about 275 million years ago as the area dried out and
sand dunes made of
quartz sand invaded a growing desert
Different situations produced different kinds of rock.
