Welcome to your assignment for today, Wednesday, March 7, 2007
Follow all instructions carefully.

Procedure: Sedimentary Rock Observations.  Use your lab (the PDF file you downloaded).

The Report Sheet page of the lab (page 78 of the lab) has a list of Rock names.  The rock names correspond to the links in the table below.

Click on each link in the table to see a picture of each rock you will be observing and describing.  Describe each rock on the Report Sheet (page 78 of the lab) in terms of clastic, chemical, or organic; composition from your reference tables, page 7, Scheme for Sedimentary Rock Identification and describe each method of lithification (see below for assistance).

Method of lithification (fill in the blanks below and write the following description for clastic sedimentary rock):

Clastic Sedimentary Rock = weathering of rock into sediment --> (fill in the blank) --> Deposition into a (fill in the blank) --> vertical sorting which forms graded (fill in the blank) --> sediments are compacted or (fill in the blank) together.

Below are the descriptions for both chemical and organic sedimentary rock:

Chemical Sedimentary Rock = oceans and large lakes can become saturated with NaCl or CaCo₃ (carbonates) as these weathered/eroded sediments are deposited by streams and rivers.  If the climate goes through an extended period of very warm temperatures and dry (arid) conditions evaporation of the body of water would occur.  As the water converts to a gas as a result of this evaporative period, these NaCl and carbonate solids will sink to the bottom of the ocean/lake and build up like other sediments (same process that leaves salt on the bottom of a glass if you allow saltwater to evaporate from the glass except on a much larger scale).  Evaporation after millions of years can leave whole oceans completely dry.  The bottoms of these evaporated oceans will contain large deposits of these evaporite (NaCl) and precipitate (carbonates).  Compaction and cementation of these evaporated solids (called evaporites/precipitates) would occur producing rock salt (NaCl), and Limestone (CaCo₃).

Organic Sedimentary Rock = produced from organic material which is basically dead plants and animals (detritus) that have been compacted and cemented together.

Use your reference tables, page 7, Scheme for Sedimentary Rock Identification to complete the Report Sheet on page 78 of the lab.

Rock Pictures: use your browser's back button to come back to this page after viewing a picture.

Watch what happens when hydrochloric acid (HCl) is dropped onto Limestone.  Why does the limestone react like this?  What is the composition of limestone that would cause this.
(allow the movie to download to your computer which may take a couple of minutes).

Once you are finished with the rock observation procedure you can go on to answering the follow-up questions at the end of the lab.

DataDrop the lab at the end of class, even if it is unfinished.  Labs that are not datadropped will be awarded a ZERO!

back to top