What are sedimentary rocks?
The surface of the Earth is continuously being eroded. Rocks are broken into smaller pieces because they are weathered down by wind, water, and ice. The weathered, tiny pieces of broken rock form into gravel, pebbles, sand, or clay. These small pieces of rock tumble into rivers, streams, lakes, and oceans, where they settle to the bottom. The tiny pieces of rock pile up and the sediments (comprised of tiny pieces of rocks, sand, soil, and remains of dead plants and animals) form flat layers. Over a long period of time, the sediments that have formed press together and form a solid rock. This solid rock that forms is called sedimentary rock. Sedimentary rocks comprise 70% of all the rocks on Earth.
Click here to see how sediments are deposited in water to begin the formation of sedimentary rocks!
Where are sedimentary rocks formed?
Sedimentary rocks are only formed on the Earth's surface.
How do sedimentary rocks form?
Sedimentary rocks form on the Earth's surface in two ways:
Click here to see how sediments are deposited in water to begin the formation of sedimentary rocks!
Where are sedimentary rocks formed?
Sedimentary rocks are only formed on the Earth's surface.
How do sedimentary rocks form?
Sedimentary rocks form on the Earth's surface in two ways:
- from clastic material (pieces of other rocks or fragments of skeletons) that have become cemented together, and
- by pressure- as layer after layer of sediments are deposited, the lower layers are pressured very tightly together under the weight of the layer above.
Characteristics of Sedimentary Rocks
- Classified by their texture and composition
- May often contain fossils
- Comprised of many layers, flat, or curved
- The pieces in the rock are pressed together or cemented tighter
- Many colors are visible
- Usually have pores between pieces
- Particle size may be the same or vary in size
Types of Sedimentary Rocks
- Sandstone: Usually red or gray in color, composed of small sand grains cemented together
- Limestone:White to gray, composed of calcite or fossils
- Conglomerate: Various colors, usually rounded pebbles and cobble stones that are cemented togther
- Shale: Dark gray, compacted mud
- Chert: White to black (mostly gray), comprised of small fossils
- Arkose: Brown color, comprised of cemented grains
Dear Geologists,
Grab your science notebooks and click here to view your assignment on sedimentary rocks!
- Geologist Joe
Grab your science notebooks and click here to view your assignment on sedimentary rocks!
- Geologist Joe