Radiocarbon Dates of Pre-Mankato Events in Eastern and Central North America.

摘要: 1) A group of samples from horizons previouslycorrelated with the upper part Cary substageconfirms correlation as reasonable and is consistently related in time to dates peat layerat Two Creeks subsequent Mankato events. 2) major glaciation affected Great Lakes region beginning 25,000 or more yr ago reachingits maximum extent about 18,000 ago. It represented by drift correlated Ohio substage and, at least part, Tazewell substage; Illinois adjacent states it correlatedwith most theFarmdale loess. 3) The ecology other associations implied bythe dated are consistent glacialthan nonglacial conditions. 4) lower till Sidney, (W-188), onwhich developed a soil considered correlative ofthe Fox series on gravels also buried tillof ago, indicates an earlier extensively exposed inOhio believed be early Wisconsin event. Table 2. List arranged agegroups. See PDF for Table 5) An glaciation, glaciations, impliedat several localities peat, gyttja, wood morethan 30,000 old, overlain till. 6) interval between middle andthe old samples, which has been determinedwithin conservative radiocarbon limits greaterthan 3000 yr, possibly order 16,000 yr,as suggested depth leaching Ohio.(The ages all discussed listed inTable 2.) 7) attempt should now made fix moreclosely reexaminein field stratigraphic sequence light discussed.