11. In general, the aquifer comprises a variety of quartz sand, well-rounded format, and has low clay content . 12. In addition, an increase in clay content of the subsoil above the hardpan was described in some places. 13. No more than half the clay content should be expansive clays with the remainder non-expansive illite or kaolinite. 14. Blocky structures are common in subsoil but also occur in surface soils that have a high clay content . 15. Combined with arable soil, high with eroded clay content makes this a most favourable area to grow grapes. 16. Colonies of " M . viator " produce initially small, conical mounds on soil with sufficient clay content . 17. Materials used in the render are commonly local sands with little clay content with fine to coarse grains. 18. The remaining clay content , such as those in the Gatower Feldflur Nature Reserve, offer the best conditions for agriculture. 19. It has a high clay content which causes it to expand when wet leading to sliding of the terrain. 20. Good dirt, Orozco said, is salt-free, contains little sand and has a clay content of at least 20 percent.
