GEOL 3235 : Introduction to Petrography

Laboratory 2a - Sedimentary Rocks

The rocks for the first exercise in Sedimentary Petrography are stored in the wooden trays.

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 wooden trays labeled Sedimentary. 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 four lab periods.

When you are finished hand in your "work sheet".