Donald P. Schwert

Changes in late Quaternary vegetation and insect communities in southwestern Ontario

Abstract The Gage Street site in Kitchener, Ontario, is a peat/marl sequence representing continuous lacustrine sedimentation from the time of deglaciation (ca. 13,000 yr B.P.) through 6900 yr B.P. Insect, pollen, and plant macrofossil remains isolated from the sediments indicate that from ca. 13,000 to 12,500 yr B.P. the region was characterized by parkland-tundra vegetation existing within thermal conditions more analogous to those today of the midboreal forest. The transition from parkland to coniferous forest at ca. 12,500 yr B.P. occurred within a climate that was only gradually warming. By the time of the spruce/pine transition at 10,500 yr B.P., an insect fauna had become established that is typical of southwestern Ontario today. The replacement of this fauna at ca. 8400 yr B.P. by one characteristic of the lowlands of the east-central United States represents the beginning of Hypsithermal conditions in southern Ontario. Vegetation and insects indicate that the climate continued to gradually warm through the mid-Holocene.

Plant and insect fossils at Norwood in south-central Minnesota: A record of late-glacial succession☆

Abstract The Norwood site in Sibley Co., Minnesota, contains 1.6 m of silt resting on till and overlain by peat. The base of the peat has been radiocarbon dated at 12,400 ± 60 and the top at 11,200 ± 250 yr B.P. The pollen, plant macrofossils, and insect remains in the basal silt consist of boreal species inhabiting open environments, but not tundra. No modern analogue exists for the insect assemblage, which includes elements of boreal forest, tundra-forest, and western affinities. The transition from an unstable open environment to a stable coniferous forest is reflected by both plant and insect fossils and is interpreted as a successional rather than a climatic event. During this time of significant biologic change, the climate is inferred to have been relatively uniform, with temperatures similar to those presently existing in the boreal forest south of the tundra-forest transition zone. The geologic and ecologic succession at Norwood is generally similar to that presently associated with ice stagnation of the Klutlan Glacier in the Yukon Territory. Localized successional sequences similar to those at Norwood are conceived to have occurred repeatedly during the melting of the Laurentide ice, and thus the proposed model has potentially broad application to the interpretation of late-glacial sequences.

Plant and insect remains from the Wisconsinan interstadial/stadial transition at Wedron, north-central Illinois

Abstract Organic material exposed within a small swale fill in Pit 6 of the Wedron Silica Sand Co. near Wedron in LaSalle County, Illinois, includes well-preserved pollen, plant macrofossils, and insect remains. This material occurs in slackwater sediment in the lower part of the Peddicord Formation, which was deposited as existing valleys were dammed by fluvial aggradation during the initial late Wisconsinan advance of Laurentide ice into the Wedron area. Wood from the organic horizon has a radiocarbon age of 21,460 ± 470 yr B.P. (ISGS-1486). The pollen spectrum is dominated by Picea, Pinus , and Cyperaceae. Plant macrofossils comprise a mix of boreal-forest taxa, including Picea, Larix laricina , and the moss Campylium stellatum ; subarctic species including Betula glandulosa, Empetrum nigrum , and Selaginella selaginoides ; along with the predominantly arctic Vaccinium uliginosum var. alpinum, Dryas integrifolia , and Rhododendron lapponicum . The insect fauna contains the western montane ground beetle Opisthius richardsoni ; several arctic-subarctic ground beetles including Diacheila polita, Helophorus sibiricus , and Pterostichus (Cryobius) caribou ; and a diverse assemblage of insects that today inhabit the boreal forest. We interpret the biotic record to record a phase in the transition from closed boreal forest to open tundra as climatic conditions deteriorated in advance of continental glaciation.

Virtual environments for education

WWWIC, the NDSU World Wide Web Instructional Committee, is engaged in developing a range of virtual environments for education. These projects span a range of disciplines, from earth science to anthropology, and from business to biology. However, all of these projects share a strategy, a set of assumptions, an approach to assessment, and an emerging tool set, which allows each to leverage from the insights and advances of the others.

Impact of Euro-American settlement on a riparian landscape in northeast Iowa, midwestem USA: an integrated approach based on historical evidence, floodplain sediments, fossil pollen, plant macrofossils and insects:

European settlement and attendant forest clearance and agricultural activities in northeastern Iowa caused changes in the landscape, vegetation, insect fauna and water quality unequalled in rate and magnitude since the melting of Wisconsinan glaciers. Historical documents show that the upper part of the Roberts Creek drainage basin was settled between AD 1840 and 1856, and the area was under intensive cultivation by 1880. Extensive soil erosion beginning at this time resulted in increased runoff and more frequent flooding; aggradation rates increased by one to two orders of magnitude over those in presettlement times, and the entire floodplain was covered with up to 1 m of sediment. Channel widening between about 1880 and 1930 allowed the stream to accommodate greater floods, overbank deposition decreased, and further deposits were restricted mostly to the channel belt. The presettlement vegetation was a stable mix of wet meadows and riparian shrubs on the floodplain, a rich aquatic community in the stream, and oak savanna on the valley walls and upland. Disturbance from soil erosion, floodplain erosion and floodplain deposition almost completely replaced both lowland and upland communities with ruderal (disturbed ground) plants, many of them introduced weeds. Regional insect communities were simultaneously affected by changes in land use. The presettlement aquatic beetle fauna was dominated by species of dryopoid beetles that today inhabit only streams of high water quality. Terrestrial beetle taxa included species of undisturbed grasslands and riparian forest. The changes in the landscape resulted in a decrease in the diversity of terrestrial beetle taxa and caused the near total elimination of dryopoid beetles in stream waters. Dominating the historic assemblages are beetles associated with dung, polluted waters and cultivated plants, including host-specific immigrant beetle species that are associated with immigrant plant species.

Mid-Wisconsinan stratigraphy and paleoenvironments at the St. Charles site in south-central Iowa

A sequence of loess-mantled sediments exposed along Clanton Creek provides the first evidence of fluvial, pedologic, and biotic environments before the last glacial maximum in south-central Iowa. Two fining-upward fluvial sequences, one inset into the other, are exposed. Radiocarbon ages indicate that the alluvial fills are about 34,000 yr old. Basal gravel in the oldest fill contains well-preserved mammoth ( Mammuthus ) bones. Sparse seeds from this horizon suggest weedy flood-plain conditions. The younger alluvial fill contains well-preserved pollen, plant macrofossils, and insects. The pollen is dominated by nonarboreal taxa and Pinus , suggesting a prairie border or savanna environment. Vascular-plant and bryophyte macofossils indicate a variety of aquatic and marsh environments on the flood plain. Insects are mostly sympatric in mixed conifer and hardwood forest that extends along latitude 47° to 49° between eastern North Dakota and New England, but forest beetles are rare, and the fauna is dominated by openground forms. The site is interpreted as an open flood plain dotted with marshes and oxbow lakes; it was surrounded by open woodland or savanna similar to that in north-eastern North Dakota at present. July temperatures at the St. Charles site were probably 3 to 5 C° cooler than those at present. The pre-loess stratigraphy of the site differs markedly from that of upland sites and demonstrates that correlation between upland and lowland sequences cannot be done without adequate dating.

Research on role-based learning technologies

One of the goals of science education is to familiarize students with an intellectual framework based on established scientific principles and general approaches that can later be used to solve science-based problems. Science is also content-based, and students must master the content of a discipline in order to succeed. The challenge for science educators is to develop educational tools and methods that deliver the principles but at the same time teach the important content material, but in a meaningful way. The paper describes research based on experimental virtual role-based environments built to explore the following beliefs: educational technology should capitalize on the natural human propensity for role-playing; students will be willing to assume roles if the environment makes it easy to do, and if the environment reinforces role-playing through careful crafting of explicit tutorial components; that educational software should be engaging, entertaining, attractive, interactive, and flexible: in short, game-like. The experiences provided to the student within these virtual worlds can be both meaningful and authentic, although some trade-offs are required to make them fun, challenging, and occasionally unpredictable.

Software tutors for scaffolding on Planet Oit

Planet Oit is a multiuser virtual environment used to teach geologic concepts and the scientific method. It is built on a structured system of modules and goals arranged so that students have freedom, but have direction as well. Intelligent software tutors explain geologic concepts, guide the players in achieving their goals, and assist them in understanding the environment. Planet Oit and its system of goals, tutors, and scaffolding are described.

Geometric Analyses of Rotational Faults.

Analyses of rotational faults in undergraduate-level structural geology laboratories can provide students with interesting applications of both orthographic and stereographic techniques. For the demonstration problem described, an orthographic/stereographic solution and a reproducible block-model demonstration pattern are provided.