This investigation will help you to:
Soils Photo Gallery, USDA-NRCS National Cooperative Soil Survey
This site includes a written description of different soil types. Also includes pictures and desciptions for the state soils.
Soil Types, University of Illinois
This site discusses soil types and particle sizes.
Soil: What is It?, USDA-NRCS
A slide presentation about soil with explanations.
Keys to Soil Taxonomy, USDA-NRCS
Online textbook covers a wide range of topics, including which soils scientists classify and how they classify them.