1. Sedimentary Rocks as the name suggests, form
from sediments, usually deposited
in horizontal layers as seen here

2. What is a SEDIMENT?
1) Solid particles, such as weathered rock fragments, plants or animal remains:
sand, clay, pebbles, shells, etc.
small pieces of broken down rocks = clasts
2) Minerals that settle out of solution onto lake and ocean bottoms, such as rock salt, dolostone, gypsum

3. But in order for the sediments to become hard
rock, the particles in the sediment must be
permanently cemented together as seen in this
sandstone
Compaction and cementation
must both happen for sedimentary
rock to form.
Minerals like quartz and calcite often serve as
the cement

4. River entering an ocean
Pressure
compacts
The sediments

5. A conglomerate is formed in a beach environment and
is composed of larger rock sediments from various
origins

6. Conglomerate boulder

8. Sedimentary rocks made of sediment grains (clasts) are called
CLASTIC SEDIMENTARY ROCKS
Sandstone, shale, conglomerate, and breccia are all clastic sedimentary rocks

9. Sedimentary rocks like this shale often contain
fossils

10. Great Salt Lake in Utah
contains many minerals
dissolved in it

11. If it were to evaporate away, it would leave
behind those minerals in the form of rock salt,
and rock gypsum.
Rocks that form in this way are
called evaporites. They are crystalline.

12. Limestone and Dolostone can precipitate from
seawater that is warm and shallow

13. The chalk cliffs of Dover are composed
of a limestone containing microscopic
shells

14. Sedimentary rocks
that are made up mostly of life forms, like shells or plant remains, are called BIOCLASTIC
Limestone and coal are bioclastic rocks

15. Larger shells are often found in limestone

16. Millions of years ago lush fern forests dominated the land

17. As these ferns died, their remains
piled up in large bogs. In many
places the decaying plant remains
became thousand of feet thick

18. After millions of years and under great pressure, coal is the rock that forms from the remains of these plants

19. Fern fossils are
often seen on
pieces of coal

20. How can you tell if a rock is SEDIMENTARY?
Look for pieces of other rocks (sand grains, pebbles, etc.)
Does it feel like sandpaper? (sand sized pieces)
Does it feel “dusty” (silt sized pieces)
Does if feel “smooth” (clay or mud)
Look for horizontal layering of the sediments
Look for a fossil
Does it react with acid (Limestone)?
Look for other sed. features (mud cracks,
cross bedding etc.)