Glossary of Soil Science Terms - Browse

quantity intensity ratio The change in quantity sorbed with change in quantity in solution. It is determined from the slope of the plot of concentration in solution vs. the quantity sorbed. Refer tosorption.

quarries [soil survey] A miscellaneous area (map unit) applied to excavation areas, open to the sky, usually for the extraction of stone (USDA, 1993).

quarry Excavation areas, open to the sky, usually for the extraction of stone ( Jackson, 1997).

quartz A framework silicate composed exclusively of silica tetrahedra.

Quaternary The period of the Cenozoic Era of geologic time, extending from the end of the Tertiary Period (about 2.6 million years ago) to the present and comprising two epochs, the Pleistocene (Ice Age) and Holocene (Recent); also, the corresponding (time-stratigraphic) “series” of earth materials ( Jackson, 1997).

quorum sensing Bacterial gene expression regulated by small molecular weight compounds (i.e., N-acy-homoserine lactones) that are synthesized only when the appropriate density (quorum) of bacterial producers is present.