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A set of activities designed to help students discover properties about order-3 spirolaterals on square grid paper is presented. The materials are prepared on worksheets designed for easy duplication. The lessons can lead to investigations involving spirolaterals of many other orders and shapes. (MP)

The Chariton Conglomerate is a quartz/limestone conglomerate of Middle Pennsylvanian age sparsely exposed in southern Iowa and northern Missouri. In Iowa it is characterized by quartz granules and rounded crinoid columnals. The objective of this study was to use detrital zircon ages to determine the provenance of the Chariton Conglomerate and possibly associated Marmaton Group sandstone beds. Detrital zircon ages were obtained for five conglomerate and two sandstone beds of the Chariton Conglomerate in Iowa, three conglomerate beds of the Chariton Conglomerate in Missouri, and two sandstone beds of the Marmaton Group in Iowa. According to the Kolmogorov-Smirnoff Test, the 12 detrital zircon age spectra were statistically indistinguishable, consistent with a common provenance for all beds. The combined age spectrum (879 zircons) showed both a young cluster (1.1 % of zircons) in the range 320-364 Ma (Late Devonian Period - Late Mississippian Subperiod) and a much older cluster (0.3% of zircons) in the range 3198-3269 Ma (Paleoarchean - Mesoarchean Eras). The Devonian Period - Mississippian Subperiod (318--416 Ma) and the Paleoarchean-Mesoarchean Eras (2800-3600 Ma) accounted for 2.8% and 3.6% of zircon ages, respectively. A model consistent with the above ages and the paleocurrent directions in the Chariton Conglomerate is an Early - Middle Pennsylvanian river originating in the Devonian - Mississippian crystalline rocks of New England and entering Minnesota - Wisconsin from the northeast to collect sediments from crystalline rocks of Paleoarchean - Mesoarchean age. However, a Middle Pennsylvanian uplift in the Minnesota - Wisconsin region is also required to produce the headwaters necessary for the production of quartz granules, which is consistent with the model of hotspot epeirogeny. [ABSTRACT FROM AUTHOR]