The crossword solution for the term 'Firm, Dry Ground' is 'HARDPAN', which is a seven-letter word. Hardpan is a dense layer of soil that is found beneath the surface of the ground. It is usually composed of clay, silt, and other minerals, and it is very difficult to penetrate. Hardpan is often found in arid regions, where the lack of moisture prevents the soil from becoming soft and pliable. Hardpan can also be found in areas with high levels of human activity, such as construction sites, where the soil has been compacted by heavy machinery.