Summary of Quaternary geology of the Municipality of Anchorage, Alaska

Schmoll, Henry R.; Yehle, Lynn A.; Updike, Randall G.

doi:10.1016/s1040-6182(99)00004-x

Cited by 12 publications

(23 citation statements)

References 58 publications

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“…Abbott and Brochmann, 2003;Cook et al, 2005;Dawson et al, 2014;Pruett and Winker, 2005) whose polymorphy has been shaped by rapid, dynamic geologic processes throughout the region (Hopkins, 1959(Hopkins, , 1973. The final formation of Cook Inlet as a geographic feature is believed to have occurred ∼14,000 years ago (Reger et al, 2007;Schmoll et al, 1999) and fossil evidence indicates immediate colonization of the region thereafter by Macoma (Schmoll et al, 1972). Cook Inlet is the most northerly site in the region with abundant benthic food supplies that occur in the absence of permanent sea or shore-fast ice during winter (Ruthrauff et al, 2013b).…”

Section: Discussionmentioning

confidence: 99%

Ways to be different: foraging adaptations that facilitate higher intake rates in a northerly-wintering shorebird compared to a low-latitude conspecific

Ruthrauff

Dekinga

Gill

et al. 2015

Journal of Experimental Biology

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At what phenotypic level do closely related subspecies that live in different environments differ with respect to food detection, ingestion and processing? This question motivated an experimental study on rock sandpipers (Calidris ptilocnemis). The species' nonbreeding range spans 20 deg of latitude, the extremes of which are inhabited by two subspecies: C. p. ptilocnemis that winters primarily in upper Cook Inlet, Alaska (61°N) and C. p. tschuktschorum that overlaps slightly with C. p. ptilocnemis but whose range extends much farther south (∼40°N). In view of the strongly contrasting energetic demands of their distinct nonbreeding distributions, we conducted experiments to assess the behavioral, physiological and sensory aspects of foraging and we used the bivalve Macoma balthica for all trials. C. p. ptilocnemis consumed a wider range of prey sizes, had higher maximum rates of energy intake, processed shell waste at higher maximum rates and handled prey more quickly. Notably, however, the two subspecies did not differ in their abilities to find buried prey. The subspecies were similar in size and had equally sized gizzards, but the more northern ptilocnemis individuals were 10-14% heavier than their same-sex tschuktschorum counterparts. The higher body mass in ptilocnemis probably resulted from hypertrophy of digestive organs (e.g. intestine, liver) related to digestion and nutrient assimilation. Given the previously established equality of the metabolic capacities of the two subspecies, we propose that the high-latitude nonbreeding range of ptilocnemis rock sandpipers is primarily facilitated by digestive (i.e. physiological) aspects of their foraging ecology rather than behavioral or sensory aspects.

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Section: Discussionmentioning

confidence: 99%

Ways to be different: foraging adaptations that facilitate higher intake rates in a northerly-wintering shorebird compared to a low-latitude conspecific

Ruthrauff

Dekinga

Gill

et al. 2015

Journal of Experimental Biology

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“…One possibility is that sediment supplies from glacial sources were limited. Schmoll et al (1999) have summarized the Holocene glacial history of the Anchorage area, particularly that of the adjacent Chugach Mountains, which contain the Matanuska and Knik glaciers. They recognize three broad age groups of Holocene moraines, Winner Creek, Deadman, and Tunnel, from oldest to youngest.…”

Section: Discussionmentioning

confidence: 99%

“…Winner Creek moraines could be f8000 14 C yr B.P., Deadman moraines could be f3500 14 C yr B.P., and Tunnel moraines apparently date to the Little Ice Age of the past few hundred years. Schmoll et al (1999) have mapped and correlated moraines of these three age groups in the Knik valley. Thus, it is possible that loess sedimentation did not begin until sometime after recession of the glaciers that built the Winner Creek moraines, if they are f8000 14 C yr B.P.…”

Section: Discussionmentioning

confidence: 99%

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Holocene loess deposition and soil formation as competing processes, Matanuska Valley, Southern Alaska

et al. 2004

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Although loess -paleosol sequences are among the most important records of Quaternary climate change and past dust deposition cycles, few modern examples of such sedimentation systems have been studied. Stratigraphic studies and 22 new accelerator mass spectrometry radiocarbon ages from the Matanuska Valley in southern Alaska show that loess deposition there began sometime after f6500 14 C yr B.P. and has continued to the present. The silts are produced through grinding by the Matanuska and Knik glaciers, deposited as outwash, entrained by strong winds, and redeposited as loess. Over a downwind distance of f40 km, loess thickness, sand content, and sand-pluscoarse-silt content decrease, whereas fine-silt content increases. Loess deposition was episodic, as shown by the presence of paleosols, at distances >10 km from the outwash plain loess source. Stratigraphic complexity is at a maximum (i.e., the greatest number of loesses and paleosols) at intermediate (10 -25 km) distances from the loess source. Surface soils increase in degree of development with distance downwind from the source, where sedimentation rates are lower. Proximal soils are Entisols or Inceptisols, whereas distal soils are Spodosols. Ratios of mobile CaO, K 2 O, and Fe 2 O 3 to immobile TiO 2 show decreases in surface horizons with distance from the source. Thus, as in China, where loess deposition also takes place today, eolian sedimentation and soil formation are competing processes. Study of loess and paleosols in southern Alaska shows that particle size can vary over short distances, loess deposition can be episodic over limited time intervals, and soils developed in stabilized loess can show considerable variability under the same vegetation.

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“…The majority of the geomorphic features used in this study were already mapped in previous studies, such as Reger and Updike (1983), Yehle et al (1990), Schmoll et al (1999), and maps produced by the Alaska Division of Geological & Geophysical Surveys (DGGS; www.dggs. dnr.state.ak.us/pubs) and the United States Geological Survey (USGS; http://www.usgs.gov/pubprod/publications).…”

Section: Geomorphologymentioning

confidence: 99%

Latest Pleistocene advance and collapse of the Matanuska – Knik glacier system, Anchorage Lowland, southern Alaska

Kopczynski

Kelley

Lowell

et al. 2017

Quaternary Science Reviews

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Summary of Quaternary geology of the Municipality of Anchorage, Alaska

Cited by 12 publications

References 58 publications

Ways to be different: foraging adaptations that facilitate higher intake rates in a northerly-wintering shorebird compared to a low-latitude conspecific

Ways to be different: foraging adaptations that facilitate higher intake rates in a northerly-wintering shorebird compared to a low-latitude conspecific

Holocene loess deposition and soil formation as competing processes, Matanuska Valley, Southern Alaska

Latest Pleistocene advance and collapse of the Matanuska – Knik glacier system, Anchorage Lowland, southern Alaska

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