To an Earth-system scientist the difference between the Quaternary period (which includes the Holocene) and the Neogene, which came before it, is not just what was living where, or what the sea level was; it is that in the Neogene the climate stayed stable whereas in the Quaternary it swung in and out of a series of ice ages.
The Quaternary forms part of the 65m-year Cenozoic era, distinguished by the opening of the North Atlantic, the rise of the Himalayas, and the widespread presence of mammals and flowering plants.
Geology deals with the now: the 10,000-year-old Holocene epoch, a peculiarly stable and clement part of the Quaternary period, a time distinguished by regular shifts into and out of ice ages.
Bowen, Quaternary Geology (1978, Pergamon Press, Oxford).
Their formation, which began in the Mesozoic Era (about 250 to 65 million years ago), continued in the Paleogene and Neogene periods and perhaps even in the beginning of the Quaternary Period (i.e., from about 2.6 million years ago).
In the succeeding Quaternary Period (about the past 2.6 million years), there was considerable oscillation of sea level, leading finally to the emergence of a low-lying isthmus that broadened northward to a low-lying open coastal plain.
Quaternary ammonium ions do not undergo such equilibration short of conditions where they decompose; their optical isomers are indefinitely stable and isolable, and the physiological effects of the two enantiomers may be profoundly different.
The principal reaction of quaternary ammonium compounds is the Hofmann degradation, which takes place when the hydroxides are strongly heated, generating a tertiary amine; the least-substituted alkyl group is lost as an alkene.
Iodide is held a hundred times as strongly as fluoride in an 8 percent cross-linked quaternary-ammonium resin; whereas in an 8 percent cross-linked sulfonic resin, cesium is held four times as strongly as lithium.
Uranium can be recovered from low-grade ores by leaching with dilute sulfuric acid oxidizing if necessary to convert uranium(IV) to uranium VI and then absorbing the negatively charged uranium sulfate complex ions on a quaternary-base anion-exchange resin.
She also served as president of the American Quaternary Association from 1978 to 1980, and she was elected to the National Academy of Sciences in 1982.
