11. The iron and humus particles released by the topsoil precipitate onto this impervious hardpan . 12. A thick layer of humus with a phosphate hardpan lies under the Pisonia forests. 13. Nine houses were flooded with mud and water when flooding poured through the hardpan desert. 14. Strong trade winds blew away most of the topsoil, leaving behind red hardpan dirt. 15. The results are primarily determined by how extensive and / or intractable the hardpan is. 16. The ditches around the circles penetrated the hardpan , helping to drain the prairie soil. 17. This block consists of the broad alluvial plains of Turee Creek flanked by hardpan plains. 18. Q . My driveway is on hardpan , and is too long to pave with asphalt. 19. There is little doubt that coarsening beaches by reducing them to hardpan and gravel affects salmon. 20. It is ingeniously and pridefully designed, with a frayed Persian carpet on the hardpan floor.
