Home About us Contact
|
Home About us Contact | ||
|
|
||
Geomorphic Settings (geomorphic + setting)
Selected AbstractsThe fluvial and geomorphic context of Indian Knoll, an Archaic shell midden in West-Central KentuckyGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 6 2002Darcy F. Morey Indian Knoll is the largest Archaic shell midden excavated by WPA archaeologists in Kentucky. Situated in a large alluvial valley, the site is not associated with a known river shoal as might be expected, making its fluvial and geomorphic setting of interest. Based on sediment cores and auger samples, undisturbed portions of the site remain despite extensive excavations. In undisturbed portions, a shell-bearing layer is overlain by a shell-free midden layer. Profiles of organic matter and calcium carbonate content for both layers are similar to those of other Green River shell middens. New radiocarbon determinations date the shell deposit at 5590,4530 cal yr B.P. Analysis of mussel species collected from the Indian Knoll indicates that shell fishing took place in a swiftly flowing, shallow to moderately deep setting of the main river channel. Overall, the prehistoric river setting adjacent to Indian Knoll was characterized by deeper water on average with variable but finer-grained substrate compared to other Green River shell midden sites. © 2002 Wiley Periodicals, Inc. [source] Geomorphic and riparian forest influences on characteristics of large wood and large-wood jams in old-growth and second-growth forests in Northern Michigan, USAEARTH SURFACE PROCESSES AND LANDFORMS, Issue 8 2007Arthur E. L. Morris Abstract Large wood (LW; pieces with diameter greater than 10 cm and length greater than 1 m) and large-wood jams (LWJs; two or more pieces of LW in contact with each other) are important components of stream ecosystems that are often distributed along stream channels in response to geomorphic and riparian forest factors that interact hierarchically. As a result, information on these relationships is valuable for predicting patterns of wood accumulation and characteristics of individual pieces of wood. We studied relationships between geomorphic and riparian factors and LW and LWJ structure in different geomorphic settings associated with old-growth and second-growth settings in Upper Michigan. We used redundancy analysis (RDA) and regression tree analysis to evaluate changes in LW and LWJ structural characteristics among geomorphic and riparian forest settings. Geomorphic factors explained 38·5% of the variability in LW and LWJ characteristics, riparian forest factors uniquely explained 18·4% of the variance and the intersection of the two categories of environmental factors (i.e. the redundant portion) was 29·8%. At the landscape scale, our multivariate analyses suggest that the presence of rock-plane bedding was an important predictor of the number of LWJs and the percent of channel spanned by LWJs. Our analyses suggest differences in relationships between geomorphic factors and LW and LWJ structure. Channel width, distance from headwaters, gradient and sinuosity were identified by regression tree analyses as the most important variables for predicting LW characteristics, while channel width and confinement were the most important variables for predicting LWJ characteristics. Old-growth settings generally contained a higher proportion of conifer and LW (both in and out of LWJs) with greater diameter and volume than in second-growth settings. Our study supports the view that restoration of wood to streams will benefit from considering the associations of wood structure with landscape and reach-scale geomorphology. Copyright © 2007 John Wiley & Sons, Ltd. [source] Archaeological site distribution by geomorphic setting in the southern lower Cuyahoga River Valley, northeastern Ohio: Initial observations from a GIS databaseGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 8 2004Andrew Bauer In this study, we compiled unpublished archival documentation of archaeological site locations from the southern part of the Cuyahoga River Valley in northeastern Ohio, USA, registered at the State of Ohio Historic Preservation Office into a Geographic Information Systems (GIS) database. Using digitized soil shapefiles to generate a geomorphic data layer, we assessed the spatial and temporal distribution of 79 known archaeological sites by landform association. This digital compilation indicates that Woodland period, Late Prehistoric, and Historic sites occur in most geomorphic settings along the river valley. In contrast, Paleoindian and Archaic sites only occur on Wisconsinan cut terraces and in upland interfluve settings, indicating that most of these documented sites are in primary contexts and have not been reworked. We discuss the distribution of archaeological sites in the study region as a function of various factors, including cultural activities, taphonomic processes, landform development, and the nature and extent of the original archaeological surveys. Observed spatial patterns of known sites clearly reflect local geomorphological controls; artifactual contexts from the earlier prehistoric periods are underrepresented in the database. We conclude that additional site surveys, as well as the excavation and documentation of new sites in this part of Ohio, are required to understand local prehistoric economies and to ascertain patterns of culturally mediated land use. © 2004 Wiley Periodicals, Inc. [source] Changes in Structure, Composition, and Nutrients During 15 Yr of Hurricane-Induced Succession in a Subtropical Wet Forest in Puerto RicoBIOTROPICA, Issue 4 2010Tamara Heartsill Scalley ABSTRACT The trajectory of hurricane-induced succession was evaluated in a network of forest plots measured immediately before and 3 mo, 5, 10, and 15 yr after the direct impact of a Category 4 hurricane. Comparisons of forest structure, composition, and aboveground nutrients pools were made through time, and between species, life-history groups and geomorphic settings. The hurricane reduced aboveground biomass by 50 percent, causing an immediate decrease in stem density and diversity indices among all geomorphic settings. After 15 yr, basal area and aboveground biomass returned to pre-hurricane levels, while species richness, diversity indices, and stem densities exceeded pre-hurricane levels. Differences in species composition among geomorphic settings had not returned after 15 yr but differences in stem densities and structure were beginning to emerge. Significant differences were observed in the nutrient concentration of the three species that comprised the most aboveground biomass, and between species categorized as secondary high-light species and primary, low-light species. Species whose abundance was negatively correlated with the mature forest dominant also had distinct nutrient concentrations. When total aboveground nutrient pools were compared over time, differences in leaf nutrients among species were hidden by similarities in wood nutrient concentrations and the biomass dominance of a few species. The observed successional trajectory indicates that changes in species composition contributed to fast recovery of aboveground biomass and nutrient pools, while the influence of geomorphic setting on species composition occurs at time scales >15 yr of succession. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp [source] | ||||||||||