Alan F. Halfen

NEOICHNOLOGICAL STUDY OF THE TRACES AND BURROWING BEHAVIORS OF THE WESTERN HARVESTER ANT POGONOMYRMEX OCCIDENTALIS (INSECTA: HYMENOPTERA: FORMICIDAE): PALEOPEDOGENIC AND PALEOECOLOGICAL IMPLICATIONS

Abstract New observations of burrowing behaviors, nest construction, and sediment-mixing patterns of the western harvester ant Pogonomyrmex occidentalis are described from a neoichnological laboratory study and compared with ichnofossil evidence. Fifty ants burrowed for six weeks in a glass-sided enclosure filled with silty clay simulating a soil with A, C, Ab, and Cb horizons. The galleries, chambers, and mound were mapped and digitally recorded every 12 hours to monitor nest development and changes in architecture. After six weeks the nest was cast with dental plaster to study above- and belowground architectural and surficial nest morphologies. Numerous, intricately interconnected galleries and chambers were constructed, with galleries averaging ~0.9 cm in diameter and chambers varying from ~3 to 10 cm long and up to 1.5 cm high. Burrowing behaviors included pulling, raking, pushing, forcing, cutting, and carrying. Sediment was removed from all horizons and deposited at the surface, resulting in a large mound. Sediment was moved upward and downward within the nest and used to reinforce walls and backfill galleries and chambers. Sediment mixing occurred within and between all horizons as well as from the surface down into the nest. This study demonstrates (1) that ants play a significant role in soil formation, and (2) that these modern ant structures are similar to those found in continental deposits as old as the Late Jurassic, including trace fossils composed of networks of interconnected, variably curved, subhorizontal to subvertical tunnels, some of which are larger in diameter than those described here and have been interpreted as chambers.

Holocene stratigraphy and chronology of the Casper Dune Field, Casper, Wyoming, USA

Activation chronologies of dune fields within the North American Great Plains are significant sources of paleoclimate information. Although many regional chronologies exist, several dune fields have been understudied, including the Casper Dune Field of central Wyoming. This study investigated aeolian dune sediment and buried soils of the Casper Dune Field. Complex parabolic and hairpin parabolic dunes dominate the eastern dune field, while simple parabolic and linear dunes dominate the western dune field. Buried soils are found throughout the dune field, though their distribution and degree of development varies. Buried soils in the eastern dune field are weakly developed with typical A-C profiles, whereas soils in the western dune field typically exhibit A-Bt-C profiles. Optically stimulated luminescence (OSL) and radiocarbon ages were used to provide a chronology of dune field activation that spans most of the Holocene. At the onset of the Holocene, alluvium was deposited first, followed by widespread dune activity ~ 10.0—6.2 ka. Following activity, the dune field stabilized until about 4.1 ka. During this stabilization period, however, reactivation occurred in at least one locality within the dune field at 5.1 ka. Subsequent aeolian activity occurred at 4.1 ka and between 1.0 ka and 0.4 ka. The resulting activation chronology is compared with those obtained from elsewhere in Wyoming and from other west-central Great Plains dune fields.

The Cockpit Country, Jamaica: Boundary Issues in Assessing Disturbance and Using a Karst Disturbance Index in Protected Areas Planning

The Cockpit Country is Jamaica’s only remaining pristine karst area and is perhaps the most significant karst landscape in the Caribbean. It may be a candidate for UN World Heritage status but its boundaries are contentious. The Karst Disturbance Index (KDI) is an important tool for karst conservation, providing an objective numerical measure of the extent to which karst landscapes have been disrupted by human activities. Its application is, however, constrained by issues of boundary determination and location, and the Cockpit Country exemplifies this phenomenon when different boundaries are determined on geomorphic, historical, existing, and proposed management criteria. Analysis of land use data from 1998, together with extensive field surveys, reveals that the measure of the extent of human disturbance is closely related to the positioning of the boundary, with the incremental inclusion of peripheral areas beyond the core forest reserve resulting in a dramatic increase in the disturbance index. Not only is this a methodological concern in using the KDI, but it also illustrates how the KDI may be useful in planning and establishing potential protected area boundaries.

Vegetation dynamics during the Pleistocene–Holocene transition in the central Great Plains, USA

The Holocene–Pleistocene transition in the upland loess-mantled regions of the central Great Plains is punctuated by the Brady Soil, which separates the late-Pleistocene Peoria Loess and the Holocene Bignell Loess. Previous research on the Brady Soil at the Old Wauneta Roadcut site in Southwestern Nebraska has produced paleoenvironmental information based on well-constrained luminescence and radiocarbon ages, stable carbon isotope data, and chemical and physical data. While the research indicated high effective moisture during formation of the Brady Soil and a shift to warm-season C4 vegetation from the cool-season C3-dominated vegetation of the Peoria Loess, those data do not provide any detail as to plant community composition and significant underlying climatic inferences. Assemblages of phytoliths and other biosilicates extracted from the Brady Soil provide specific information on vegetation communities and indicate shifts of plant taxa comprising these assemblages. Short-cell phytolith count data reveal a shift from dominance of Pooideae (C3) grasses, with relatively large numbers of arboreal dicot spheres and a few Cyperaceae (sedge) present in a savannah or open woodland in the Bølling-Allerød, to a mixed, open Chloridoideae (C4) and Pooideae (C3) grassland in the early-Holocene. Stipa-type Pooideae, a cool-season grass preferring drier soil conditions, marks the onset of the Younger Dryas. Large-cell phytoliths such as long cells, bulliforms, and trichomes, provided further definition of the climate history. This comprehensive biosilicate study of the Brady Soil has provided a more detailed paleoclimatic reconstruction than that generated with bulk sediment-derived δ13C data, or even with short-cell phytolith data alone.

A New Stereoscopic (3D) Media Database and Teaching Strategy for Use in Large-Lecture Introductory Geoscience Courses

ABSTRACT Stereoscopic displays provide geoscience instructors with the ability to teach students the fundamental, and inherently three-dimensional, components of landforms and landscapes; yet the prevalence of such displays in higher education is limited. As costs of these systems continue to decrease, more instructors may wish to take advantage of stereoscopic display systems in their classroom. This paper serves as a guide for instructors who wish to install and use their own stereoscopic display systems using a case study conducted at the University of Kansas. The operational aspects covered include: creating stereo images, displaying stereoscopic images, selecting a stereoscopic display, and developing a new teaching strategy that incorporates the stereo system into the classroom environment. Additionally, a new database of stereoscopic media is provided to help promote the implementation of stereoscopic displays and free and open distribution of 3D teaching material.

Book review: The Geoarchaeology of Lake Michigan Coastal Dunes

Inland and coastal dune fields of North America contain important geomorphic and stratigraphic records of environmental change that can be tied to shifts in late Quaternary climate, particularly during the Holocene. Additionally, the affinity of early Americans and aeolian dune fields is well documented (e.g. Holliday, 2001), providing archaeologist sites to investigate the early peopling of North America. The Geoarchaeology of Lake Michigan Coastal Dunes is the second volume in the Michigan Environmental Research Series, edited by James A. Robertson, a staff archaeologist within the Michigan Department of Transportation (MDOT). The first volume of the series, which some readers may find interesting, is by Monaghan and Lovis (2005). The present volume begins with an introduction aimed at providing important context to archaeological studies within dunes. This context includes basic background information on dune field activation and evolution in relation to changing climate. The chapter outlines some basic research design such as site selection and field data collection. Chapter 1 could be lightly skimmed by the experienced scientist. However, this basic background information is crucially important for novice researchers and the general public, as much of the text in later chapters relies on an understanding of these concepts. Chapter 2 provides a historical and interpretive perspective of Lake Michigan coastal dune archaeological sites by highlighting key research since the early 1900s. Although some site investigations predated the 1960s, most of the significant research in the Lake Michigan Basin took place in the 1960s and 1970s. Significant research included the University of Michigan Museum of Anthropology 1962–1963 survey, the Michigan State University 1972–1973 survey and excavation, and the detailed studies of several sites – each of these sites are briefly described within the chapter. Aeolian processes, dune formation and modification and dune activation and stabilization cycles are described in Chapter 3. The information provided on these topics is cursory, yet sufficient for the text. A brief historical perspective of coastal dune research is also provided. The chapter concludes by providing new chronological control of dune formation from the northern part of the Lake Michigan Basin. The new chronology suggests a cyclic nature of dune formation that dates to c. 5 ka BP. Unlike previous dune studies, the ages provided in this report suggest that dune activity was not directly driven by lake-level fluctuations associated with the Nipissing transgression and regression. Instead, dunes appear to have been formed episodically with major building episodes between c. 3.5 and c. 2 ka BP and a rebuilding episode after c. 1 ka BP. Chapter 4 discusses the relationships between dune formation, lake levels and human settlement within the Lake Michigan Basin. In particular, the authors highlight the timing of major lake transgressions and regressions, including high water levels from c. 6 to c. 4.5 ka BP, low water levels between c. 4 and c. 3.5 ka BP and cyclic high and low water levels within the last 2000 years, which the authors contend relate to major global climate change events (e.g. the Mediaeval Warm Period and ‘Little Ice Age’). Six new dune archaeological sites that were investigated between 2006 and 2008 are described in Chapter 5. Like in previous chapters, each site is described in terms of location, stratigraphy, chronology and regional context. Information from each site has helped contribute to the overall larger-scale patterns of dune formation within the Lake Michigan Basin. Chapter 6 provides a summary, a discussion and a synthesis on the data described in previous chapters. Particular emphasis is given to the chronology of dune formation and modification and the environmental/climatological factors responsible for dune formation in the Lake Michigan Basin. The chapter also presents a spatio-temporal model of coastal dune formation, in which dune formation events are related to a lagged response to coastal erosion as well as to other extrinsic climatological factors, such as storms and drought. Finally, Chapter 7 is a case study in which local land managers are tasked with identifying landscapes and dune areas to be managed to varying degrees in proximity to a major roadway. The authors use their interpretations from previous chapters to identify specific areas to be put under land management. This chapter is relatively short, but provides a useful guide directed to the general public and the MDOT engineers/scientists in matters concerning the true complex nature of these dune systems. Following the main text are three appendices. Appendix A details the chronological methods employed including optically stimulated luminescence (OSL) sampling and dating techniques. Appendix B is a table of all radiocarbon and OSL ages reported in the text. Finally, Appendix C provides detailed archaeological site descriptions. Overall, the book is written by three respected scientists with several decades of experience researching the topic. Furthermore, the scientific reasoning behind the data presented is sound, including the sampling and dating methods of the chronological data. The effort of the authors to condense such large quantities of data in a succinct text is also appreciated. The text likely has a limited audience, which the authors themselves acknowledge as MDOT scientist/engineers, archaeologists, earth scientists, park interpreters, land managers and the general public. Nevertheless, those interested parties will find great quantities of useful data and contextual synthesis. Perhaps the most important contribution of this compilation is the collection and dissemination of geographical, chronological, stratigraphic and anthropological data associated with dune landscapes in Michigan. As the authors note throughout the text, data from individual sites provide important local information. However, the larger-scale questions of changing regional environments can only be answered through regional synthesis of all data. Other researchers in the fields of aeolian science have recognized the importance of compiling data for regional synthesis, and similar projects aimed at compiling data on dune fields have been undertaken in the Great Plains (Halfen and Johnson, 2013) 497449 HOL23910.1177/095968361349 7449The HoloceneHolocene book review 2013