Hello Dave, > Perhaps some of you can explain something regarding soils to me This may confuse you thoroughly, but I'll try. The terms relating to soil textures are based upon the relative proportions of the 3 basic mineral sizes making up the soil. These terms were developed for use in geology and the study of land profiles They are, in descending order, sand, silt, and clay. Within these groupings are subdivisions that are used in certain specific applications. . In addition, some countries may have different definitions of the exact size of each of these basic particles. For the most part these subdivisions don't matter in our potting soils. To determine a soil type by texture, the soil triangle is used. See http://www3.hcs.ohio-state.edu/wiki/index.php/… for an example. Note well that these terms apply to the soil's texture based on the mineral content of the sample, and do not include organic matter. In gardening both in the ground and in containers, we do add organic matter, and thus create "a clay soil, rich in organic matter" and other such mixes. The addition of organic matter will affect the texture as we describe it using the same terms as the geologist's soil triangle. Therefore, (sounds like I know what I'm talking about, sort of) adding organic matter that has the sample sort of looking and feeling like the mineral definition is our definition. Obviously, the size of the organic matter will alter the mix; pine cones and sawdust as organic additions may both be pine, but size does matter! The finished soil mix does cause many chemical and mechanical things to happen. Absorption and adsorption of other additions such as fertilizers or insecticides, perviousness of liquids and gasses and the degree of retention or rejection of these, and the esthetics of the mix - "Does my bright orange soil really make my Clivia stand out?" Of the many sites available under "soil triangle', one of the easiest to follow in my opinion is from NASA http://soil.gsfc.nasa.gov/pvg/texture1.htm And, an abstract concerning porosity of soils can be read at http://springerlink.com/content/y67522x3100h8411/ I really like your upside down description, thank you for it. Gary in Hilo, HI, zone 14 If there was a number that high, where it rains every day and in the winter it rains all day. 5000mm/year