There are a few different kinds of Journals/Magazines/Periodicals.

Popular Journals:   are basically there for entertainment purposes.  They should not be used for scientific reports.
       Examples: Sports Illustrated, People

Substantial Journals:  Attempt to get across complex ideas in a simple way.  Don´t include very many details, or cite many sources.
       Examples: Scientific American, Psychology Today, Time, Newsweek

Scholarly Journals: Report the results of an experiment or investigation.  These articles are very technical, and are written by and for researchers in the field.
       Examples:  American Mineralogist, Journal of Geophysical Research

For this assignment, we´re going to concentrate on Substantial Journals.

Finding Journal Articles of Interest--Using the Indexes:

In order to make it easier to find journal articles relevant to your research, some companies have decided to index the articles from many journals, allowing you to do one search across all the journals to find the articles you want. 

For the Earth Sciences, there are several indexes that may be useful for you:

To find Substantial Articles:

      Wilson´s Reader´s Guide
      ProQuest Research Library

To find Scholarly Articles:

       GeoRef
       Meteorological and Geoastrophysical Abstracts
       INSPEC
      Compendex