University of Alaska Gulkana Glacier Expedition 1961

Glaciological studies initiated during the summer of 1960 on Gulkana Glacier in the central Alaska Range by members of the Department of Geology, University of Alaska, were continued during the summer of 1961. ... The two-man field parties, each led by a graduate student of the University of Alaska, were in the field from June 1 to September 1. The two field parties made, respectively, a detailed ablation study and a study of the surface motion. ... Larry Mayo led the party that concentrated on detailed mapping of ablation and accumulation, and recording local weather and net total radiation. Seventy-nine ablation poles and twenty-five snow pits were used to measure ablation and accumulation on the 3.5-mile-long glacier. Continuous weather observations were made for 3 months. The main weather station was located near the centre line of the glacier at an altitude of 4,800 feet. Every 12 hours measurements were made of wind, precipitation, and ablation on snow, ice, and morainal surfaces. Continuous records were made of temperature, humidity, and net total radiation. ... A second weather station for continuous temperature measurements was at an altitude of 5,600 feet on the glacier. ... Seventy-five of the ablation stakes were used in the surface motion study. This part of the program was led by Eugene Moores and consisted of the following: (1) an overall program of locating weekly, monthly, and bimonthly the position of all 75 stakes, (2) short-interval studies consisting of daily observations of seven stakes and 2-day observations of 32 stakes, (3) resurvey of the transverse profiles established in 1960, (4) extension of the triangulation net, and (5) locating stakes in the tributaries feeding the main ice streams. The short-interval studies concentrated on an area below the ice fall extending across the width of the glacier, including two stakes on different blocks at the top of the ice fall. Differential motion between ice streams was also investigated. ... Gravity measurements were made along one longitudinal and three transverse lines on the glacier. ..

University of Alaska Gulkana Glacier Expedition

During the summer of 1960 glaciological investigations were initiated on Gulkana Glacier in the central Alaska Range by members of the Department of Geology, University of Alaska. The programme is being supported by a grant from the National Science Foundation awarded to Dr. Troy L. Péwé, project supervisor and head, Department of Geology. Interior Alaska is a physiographic and climatic area heretofore almost neglected in glacier studies, in contrast to southeastern Alaska. The little work that has been done indicates that the glaciers in the interior deserve attention from the standpoint of present and historical fluctuations and studies of flow, ablation, and structure. At least two glaciers in the central Alaska Range are of special interest inasmuch as they have undergone advances as rapid, or more rapid than any others in the world. Gulkana Glacier lies on the south side of the Alaska Range 4 miles east of the Richardson Highway and about 135 miles southeast of Fairbanks. This glacier was chosen on account of its accessibility, size, structure, and because a 50-year photographic record of it is available. The glacier is 2.5 miles long and flows essentially to the south, the average width is about 1 mile. On the western side an ice fall divides the glacier roughly in half. The lower half is composed of three ice streams. The altitude of the terminus is 3950 feet and that of the ice in the cirque areas 6500 to 7000 feet. ..

Deposition of Sediment in the Iowa River at Iowa City, Iowa

The Iowa River in the vicinity of Iowa City (Fig. 1.) is a mature stream which meanders over the Kansan and Iowa till plains in its course to the Mississippi River. The river, gathering water and sediment from the 3,230 square miles of the drainage basin which lies up stream from Iowa City, flows by as a muddy stream with an average discharge of 1,432 cubic feet per second (Crawford, 1942). Although sometimes heavily charged with sediment, it is on the whole not a heavy suspended sediment carrier as the average concentration of sediment in parts per million over a three year period as tested at Iowa City was 674 (Lane, 1945)

Genesis of active sand-filled polygons in lower and central Beacon Valley, Antarctica

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Permafrost and Periglacial Processes 20 (2009): 295-308, doi:10.1002/ppp.661.Nonsorted polygons with sand-filled wedges were investigated in lower and central Beacon Valley, Antarctica (77.82ºS, 160.67ºE) using field observations coupled with a 2-m resolution Digital Elevation Model and a high-resolution aerial photograph. A gasoline-powered concrete breaker was employed to expose the sediments of four representative polygon centers and six wedges from geomorphic surfaces containing tills of two different ages. The excavated polygons ranged from 9 to 16 m in diameter (average = 12 m); the sand-filled wedges ranged from 0.2 m to 2.5 m in width (average = 0.9 m). The top of ice-bonded permafrost ranged from 12 to 62 cm in depth (average = 33 cm) in the polygon centers and from 64 to >90 cm (average = >75 cm) in wedges. One active thermal contraction fissure generally was apparent at the surface, but excavations revealed numerous inactive fissures. The wedges contain sand laminations averaging 3 mm in width when viewed in cross section. Although most of the polygons were of the sandwedge type, some contained ice veins up to 1 cm in width and could be classed as composite wedges. Three stages of polygon development were observed, including strongly developed polygons on Taylor II surfaces (ca. 117 ka), moderately developed polygons on Taylor III surfaces (ca. 200 ka), and poorly developed polygons on Taylor IVa and older (ca. >1.1 Ma) surfaces. This retrogressive development may be due to sublimation of ice-bonded bonded permafrost following thermal cracking. With the drop in ice content, the thermal coefficient of expansion is lowered, which causes a reduction in tensile stresses.This research was supported by NSF grant OPP06336629 to MK

Transient Storage as a Function of Geomorphology, Discharge, and Permafrost Active Layer Conditions in Arctic Tundra Streams

Transient storage of solutes in hyporheic zones or other slow-moving stream waters plays an important role in the biogeochemical processes of streams. While numerous studies have reported a wide range of parameter values from simulations of transient storage, little field work has been done to investigate the correlations between these parameters and shifts in surface and subsurface flow conditions. In this investigation we use the stream properties of the Arctic (namely, highly varied discharges, channel morphologies, and subchannel permafrost conditions) to isolate the effects of discharge, channel morphology, and potential size of the hyporheic zone on transient storage. We repeated stream tracer experiments in five morphologically diverse tundra streams in Arctic Alaska during the thaw season (May–August) of 2004 to assess transient storage and hydrologic characteristics. We compared transient storage model parameters to discharge (Q), the Darcy-Weisbach friction factor (f), and unit stream power (ω). Across all studied streams, permafrost active layer depths (i.e., the potential extent of the hyporheic zone) increased throughout the thaw season, and discharges and velocities varied dramatically with minimum ranges of eight-fold and four-fold, respectively. In all reaches the mean storage residence time (tstor) decreased exponentially with increasing Q, but did not clearly relate to permafrost active layer depths. Furthermore, we found that modeled transient storage metrics (i.e., tstor, storage zone exchange rate (αOTIS), and hydraulic retention (Rh)) correlated better with channel hydraulic descriptors such as f and ω than they did with Q or channel slope. Our results indicate that Q is the first-order control on transient storage dynamics of these streams, and that f and ω are two relatively simple measures of channel hydraulics that may be important metrics for predicting the response of transient storage to perturbations in discharge and morphology in a given stream