GEOL 3235 : Introduction to Petrography

Laboratory 2b - Sedimentary Rocks

The rocks for the second exercise in Sedimentary Petrography are stored in the cardboard boxes marked S-40. A few of the samples may be missing. Don't worry about that.

Prepare a Table with the following columns -- Sample Number -- Gross Characteristics -- Name. Look at each sample. The first question you should ask your self is "What Type of Rock Is This". Remember that rocks don't come in a box labeled S(edimentary)-40. Are there individual grains? Do the grains interpenetrate? Do the grains show signs of shape modification?

Is it a coarse clastic ... a fine clastic ... a "biochemical" or something else. Do this for each sample. Then, look at all of the coarse clastics ... work together and try and name each of the samples. Then do the same for the fine clastics and then for the biochemical rocks.

For each of these broad groups you will need to do what ever is appropriate to provide an appropriate name. That is, for the coarse clastics you will need to identify and estimate the percentages of the framework grains. For the fine clastics you will need to determine if the samples are fissle or non-fissle. For the biochemical folks you will need to use Folks classification and determine the nature of the allochems and the orthochems.

Try and get this done in the next two lab periods.

When you are finished come find me and I will find some other samples that you can look at.