There is no one classification of soil types. People describe it in all kinds of ways - sandy, clay or loam; good or poor; heavy or light; and also by how much sand, silt and clay are present it in. Here is where you can find a listing of soil types according to one such classification with their characteristics.
The University of Illinois' extension web site tells about the formation and composition of soil, types of soil, soil profiles and conservation of soil. It also has some interesting soil-related experiments.
BBC's gardening site is an useful resource should you want to analyse the soil in your yard, and the Chemistry.org portal has an interesting experiment you can download as a PDF to test the pH of soil to discover how acidic it might be.
Not surprisingly, the ground beneath our feet is a key focus of conservationists. Soil conservation is a subject of much scientific enquiry.It is essential to know what are the different ways in which we can conserve soil and prevent erosion. For details visit this website.
Read more here about how scientists have developed an innovative new test for a quick and reliable diagnosis of potential contamination sites.