Sedimentary Rocks

As previously stated in last weeks notes, sedimentary rocks are made from sediments, or broken pieces of rock. All sedimentary rocks have been deposited in some way, usually in a water environment (as opposed to igneous rocks, which are formed by solidification from melted rock). Sedimentary rocks are classified into three groups based on how they were deposited: clastic, chemical, and organic.

Sedimentary rocks are generally formed in four basic steps:

  • Layers of sediment are transported and deposited at the bottom of rivers, lakes and oceans.
  • Over millions of years, layer after layer of sediments is deposited on top of each. Each layer gets buried and compressed more and more through time.
  • The salts that are present in the layers of sediment start to crystallize out as the water is squeezed out from the buried layers. These salts help to cement the particles together.
  • Finally, the bottom layers slowly turn into rock.
Homework:

See homework due for Friday, 12/19/08. We will review the homework questions on Tuesday.

Test on Igneous Rocks: Monday, 12/22/08

En Español

Las piedras sedimentarias son formadas generalmente en cuatro pasos básicos:
  • Capas de sedimento son transportadas y son depositadas en el fondo de ríos, los lagos y los océanos.
  • Sobre millones de años, capa encima de capa de sedimentos son depositada. Cada capa es enterrado y comprimido cada vez más por tiempo.
  • Las sales que son presentes en las capas de sedimento se cristalizan cuando el agua es exprimida de las capas enterradas. Estas sales ayudan a cementar las partículas juntos.
  • Por fin, las capas en el fondo lentamente se vuelven piedra.

HAPPY HOLIDAYS!

"FELIZ NAVIDAD"

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