Mapping the physiography of Michigan with GIS

Abstract

We present a new physiographic map of Michigan, that is also available interactively, online. Only four, small-scale physiographic maps of Michigan had been previously published. Our mapping project made use of a wide variety of spatial data, in a GIS environment, to visualize and delineate the physical landscape in more detail than has been done previously. We also examined many of the unit boundaries in the field, using a GIS running on a GPS-enabled laptop. Unlike previous physiographic maps, the online version of the map enables users to query the criteria used to define each of the 224 boundaries of its 10 major and 91 minor physiographic units. The interactive nature of the online version of the map is a unique enhancement to physiographic maps and mapping. Our study also provides data on the number and types of criteria used to define each of the 224 unit boundaries within the map. Most of our unit boundaries are based on data derived from 10-m raster elevation data and NRCS soils data, e.g., relief, soil wetness, escarpments, landscape fabric, and parent material characteristics. Data gleaned from NRCS SSURGO county-scale soil maps were a strength of the project. [Key words: Michigan, physiography, landforms, soils, GIS, mapping]     

Introduction: Geographic Contributions to Agrobiodiversity Conservation

Abstract

Since the period of bank deregulation in the 1980s, deferred deposit loan operations, better known as payday lenders, have become commonplace in the landscapes of many American cities. At the same time, traditional banking facilities have become less common, especially in the inner city. Growing disparities in the type of and accessibility to credit in the inner city has generated calls for greater regulation to curb practices by payday lenders that critics claim disproportionately affect poor and minority consumers. Payday lenders argue that they serve communities neglected by traditional banks. This article analyzes the site-location strategies of banks and payday lenders in metropolitan Louisiana, and in Cook County, Illinois, and finds that disenfranchised neighborhoods are simultaneously targeted by payday lenders and neglected by traditional banks. The implications these findings have for public policy and for ongoing discourses on the urban condition, race, and class are briefly discussed.

     

The use of diatom records to establish reference conditions for UK lakes subject to eutrophication

A knowledge of pre-disturbance conditions is important for setting realistic restoration targets for lakes. For European waters this is now a requirement of the European Council Water Framework Directive where ecological status must be assessed based on the degree to which present day conditions deviate from reference conditions. Here, we employ palaeolimnological techniques, principally inferences of total phosphorus from diatom assemblages (DI-TP) and classification of diatom composition data from the time slice in sediment cores dated to ~1850 AD, to define chemical and ecological reference conditions, respectively, for a range of UK lake types. The DI-TP results from 169 sites indicate that reference TP values for low alkalinity lakes are typically <10 μg L⁻¹ and in many cases <5 μg L⁻¹, whilst those for medium and high alkalinity lakes are in the range 10–30 and 20–40 μg L⁻¹, respectively. Within the latter two alkalinity types, the deeper waters (>3 m mean depth) generally had lower reference TP concentrations than the shallow sites. A small group of shallow marl lakes had concentrations of ~30 μg L⁻¹. Cluster analysis of diatom composition data from 106 lakes where the key pressure of interest was eutrophication identified three clusters, each associated with particular lake types, suggesting that the typology has ecological relevance, although poor cross matching of the diatom groups and the lake typology at type boundaries highlights the value of a site-specific approach to defining reference conditions. Finally the floristic difference between the reference and present day (surface sample) diatom assemblages of each site was estimated using the squared chord distance dissimilarity coefficient. Only 25 of the 106 lakes experienced insignificant change and the findings indicate that eutrophication has impacted all lake types with >50% of sites exhibiting significant floristic change. The study illustrates the role of the sediment record in determining both chemical and ecological reference conditions, and assessing deviation from the latter. Whilst restoration targets may require modification in the future to account for climate induced alterations, the long temporal perspective offered by palaeolimnology ensures that such changes are assessed against a sound baseline.     

Abstract databases as information sources in economic geography

The limitations of existing information sources on mergers/acquisitions within the EU are a serious obstacle to the study of the restructuring of the European production system. The experience of using a computerized abstracting service as a source of information on mergers/acquisitions in the chemical industry is reviewed. This experience informs an assessment of the strengths and weaknesses of similar databases as information sources in economic geography. The proliferation of such databases, together with advances in text management software, suggests that their potential has not been fully appreciated. This potential is considerable in providing easy access to detailed factual information on economic events and processes at continental and global scales. It is, however, strictly limited when it comes to interpreting the corporate strategies and motivations responsible for these developments.     

The Swedish model for groundwater policy: legal foundations, decision-making and practical application

Public policy concerning groundwater is often complex, with diverse competing interests. With many countries facing similar challenges, it is instructive to examine the policy approaches that have and have not worked abroad. This article contributes to an international exchange of ideas on how best to approach these common problems by explaining how Sweden regulates its groundwater resources. From constitutional foundations to the practical details associated with applying existing policy, a synopsis is provided of groundwater jurisprudence in Sweden. Multiple governmental agencies are involved with groundwater policy in Sweden; this decentralized approach is probably a function of the natural abundance of clean aquifers throughout the country. Historically, the easy accessibility of high-quality groundwater made it a low priority in the context of environmental policy. It has simply never been an economic necessity to control groundwater resources through a single, unified governmental agency. Sweden is lagging behind many industrialized countries when it comes to implementing policies that protect and manage groundwater. Despite this, there are elements of Sweden’s approach that are highly innovative and possibly unique globally and which therefore merit discussion.     

An ancient seismite response to Taconian far-field forces: the Cane Run Bed, Upper Ordovician (Trenton) Lexington Limestone, Central Kentucky (USA)

The Cane Run Bed is a prominent unit of micrograined limestone and shale of distal storm origin in the lower part of the Late Ordovician (late Chatfieldian; late Caradoc) Lexington Limestone (Trenton) in central Kentucky, USA. The unit's prominence relates to presence of up to three horizons of penecontemporaneous, soft-sediment deformation that form a distinctive event bed; equivalent horizons of different lithology are also deformed. Concurrence of four lines of evidence, including deformation consistent with a seismogenic origin, widespread distribution in temporally and stratigraphically constrained horizons, a pattern of increasing frequency or deformation intensity toward likely epicentral areas, and the ability to exclude other likely causes, points strongly to a seismogenic origin for each horizon. This interpretation is bolstered by the facts that the deformation contains random fold axes, crosses facies boundaries, is associated with a periodically reactivated basement structural lineament, and crosscuts undeformed beds from both above and below. Moreover, mapping the distribution of deformation intensity allows for the interpretation of possible epicentral areas. The association of Cane Run deformation with other sedimentologic-stratigraphic anomalies related to reactivated basement faults, as well as their coincidence with the inception of a Taconian tectophase, suggest that Cane Run seismites are one of several responses to the distal transmission of far-field forces from the coeval Taconian orogeny into the foreland, largely via zones of basement structural weakness. Units like the Cane Run Bed and its equivalents, whose seismogenic origins can be confidently demonstrated, suggest that seismicity must have had a substantial influence at times on epicontinental sedimentation, even in seas far removed from orogenic sources of stress.     

Ecological consequence of the introduction of the polychaete Marenzelleria cf. viridis into a shallow-water biotope of the northern Baltic Sea

Effects of the North American polychaete Marenzelleria cf. viridis on a simple shallow-water benthic community of the northern Baltic Sea were studied in a field experiment combining natural densities of dominating macrofaunal species. The presence of M. cf. viridis increased benthic production (chlorophyll a) and reduced the survival of the native polychaete Nereis diversicolor. Adult Macoma balthica caused a significant mortality on M. cf. viridis whereas adult Cerastoderma glaucum had no effect on M. cf. viridis. We suggest that the competitive interactions between M. cf. viridis and M. balthica are a possible key factor determining the distribution pattern of M. cf. viridis in the Baltic Sea.     

Temporal patterns of arid-humid transitions in the south-eastern Arabian Peninsula based on optical dating

The Rub Al Khali aeolian system of the Arabian Peninsula is the world's largest erg. While the region is presently hyper-arid, evidence for multiple past humid periods has been documented in previous studies. Radiocarbon dating of lacustrine, travertine and palaeogroundwater deposits suggests that the climate was humid at 10–6 and 35–25 ka. These phases have been associated with summer rainfall increases occurring in tandem with an intensification and northward migration of the monsoon system during Northern hemisphere precessional maxima. Published optical dating studies have focused on preserved sand dune and aeolianite deposits to establish ages for the intervening arid phases. Here we present a summary of this work and additional optical dating results for samples of aeolian sediment from a deep drill core, which provides insights into the style of barchan dune accretion in the Liwa region of the United Arab Emirates. The large dune accreted rapidly during the mid-late Holocene. The results suggest that the transitions from humid to arid conditions and resulting accumulation of aeolian sediment in the form of large bedforms occurred abruptly at around 6 ka. Further aeolian sedimentation has not been constant since that time, with initial gradual dune growth followed by rapid vertical accretion, and possible termination of accumulation around c. 2 ka.