Core Studies and Related Glaciological Investigations
tion occurred in a motor within, the probe, creating an emergency situation that resulted in freezing-in of the probe at the 200 m depth. Initial attempts to free the probe by using a glycol solution and hydraulic jacks were not successful. The field trials showed that the melt-extraction principles are sound. Valuable experience gained during the tests will lead to improved design and construction criteria being incorporated into the new probes that are currently being built at the Institute of Physics, University of Bern, for use at Byrd Station in 1969-1970. In addition to the borehole sample, five CO 2 samples were extracted from different depth levels in the "Lead-Mine" ice tunnel at Byrd Station. Each sample consists of a few hundred liters of air pumped from the firn and trapped on molecular sieves. These samples will contribute to the understanding of the processes of air inclusion durine flfi,wll glacier ice.
transferred by refrigerated truck to cold storage facilities at Littleton, New Hampshire. The assistance of the drill crew and personnel of Task Force 43, who together performed most of this work, is gratefully acknowledged. The drill hole at "Old Byrd" (drilled in the 19571958 summer) is still accessible for temperature and deformation measurements above 200 m. Originally 14.6 cm in diameter and 309 m deep, this hole has closed off to less than 6.0 cm at 200 m. Closure rates in the top 200 m have remained essentially linear at these lower stresses, in marked contrast to the accelerating closure rates observed at the higher stresses below 200 M.
Results of seven years' measurements along two 10-km-long accumulation-stake lines that traverse the undulating snow surface around Byrd Station show that the snow has been accumulating at the rate of
References Langway, C. C., Jr., H. Oeschger, B. Alder, and A. Renaud. 1965. Sampling polar ice for radiocarbon dating. Nature, 206 (4983): 500-501. Oeschger, H., B. Alder, H. Loosli, and C. C. Langway, Jr. 1966. Radiocarbon dating of ice. Earth and Planetary Science Letters, 1: 49-54. Oeschger, H., B. Alder, and C. C. Langway, Jr. 1967. An in situ gas-extraction system to radiocarbon date glacier ice. Journal of Glaciology, 6(48) : 939-942. Ueda, H. T., and B. L. Hansen. 1967. Installation of deepcore drilling equipment at Byrd Station (1966-1967). Antarctic Journal of the U.S., 11(4): 120-121.
Ueda, H. T., and D. E. Garfield. 1968. Deep-core drilling program at Byrd Station (1967-1968). Antarctic Journal of the U.S.,III (4): 111-112.
Core Studies and Related Glaciological Investigations
5cm
ANTHONY J . GOW U. S. Army Cold Regions Research and Engineering Laboratory Participation in the 1968-1969 antarctic field season was limited to processing cores from the deep drill hole at Byrd Station, conducting further measurements of closure in the 309-rn drill hole at the old Byrd Station, and remeasuring accumulation at snow stakes around Byrd Station. Approximately half of the total length of ice cores (1,100 m) from the deep drill hole was packed and returned to the United States aboard USN Wyandot. The shipment reached Davisville, Rhode Island, on March 15, 1969, and the cores were then 124
Dirt-ice bands and a fragment of granite in core from 2,162-rn depth (2 m from bottom of ice sheet) at Byrd Station.
ANTARCTIC JOURNAL
10 to I cm of water equivalent annually. This is approximately 50 percent less than that measured at "Old Byrd" during the IGY. Depressions are still accumulating appreciably more snow than the crests of these undulations. Surface elevations were remeasured to determine if these undulations are actually migrating, but the results were inconclusive. Core studies in the laboratory at Hanover, New Hampshire, show that the cores are still relaxing (manifested by a density decrease with time) and that expansion due primarily to crack formation has been greatest (0.6 percent in 16 mon t hs) in brittle ice from between 800- and 900-m depth. Deeper bubblefree ice shows little evidence of brittle cracking; this lack of cracks is attributed to the strongly oriented crystal structure of the ice, which is apparently able to dissipate much of the strain associated with expansion upon release from high confining pressures. The disappearance of air bubbles in the ice between 900 and 1,100 m, after bubble diameters have decreased to about 0.15 mm, suggests attainment of a critical diameter of bubble, which at the prevailing overburden pressures (80 to 100 bars between 900 and 1,100 m) encourages air molecules to diffuse into the ice, possiLly as clathrate hydrates of air. Bubble-like inclusions of air are now appearing in some abundance in ice originally devoid of all trace of bubbles.
MACARONI POINT 6255 •S LAND ERUPTION CENTER 1967 IF
CHILEAN BASE MOUNT X POND 542 In BLACK GLACIER
•ARGENTINE BASE 1;
BAILY HEAD BRITISH BASE .
CRATER LAKE 63O0S
. MOUNT KIRKWOOD KWOOD 460
62
Fig. 1. Deception Island.
UNNAMED GLACIER GI DECEPTION ISLAND 0 - 00
Glaciology and Glacial Geology on Deception Island
800 EQUILIBRIUM 900 LINE
JEAN-ROLAND KLAY'
and
1000
OLAV ORHEIM2
DO
Institute of Polar Studies The Ohio State University
Deception Island (63°S. 60°10'W.) is a circular volcanic caldera with a radius of about 6 km (Fig. 1). In November and December 1967, a series of explosive volcanic eruptions occurred NNhich blanketed part of the island with volcanic material. The effects of this eruption on the glaciers and geomorphology were investigated during January and February 1969 by a three-man party from the Institute of Polar Studies. Through stratigraphic studies (carried out under glaciological investigations conducted by Orheirn, measurements of snow thickness and ablation, and meteorological observations, the mass balance was determined for an unnamed valley glacier (G 1 in Fig. 1, Fig. 2). The ash layer from the 1967 eruption (from ' Glacial Geology.
'Glaciology.
July—August 1969
00
DIVIDE
100 0
I
300 0
500m
I I
1500 ft
CONTOUR INTERVAL 100 ft Fig. 2. Unnamed glacier G 1, Deception Island. Based on Directory of Overseas Survey map of Deception Island, scale 1:25,000. The circles and the numbers refer to the stakes.
1-2 cm thick in the accumulation area) was extremely well marked and will be an excellent reference horizon for future stratigraphic studies. In the abla125
transferred by refrigerated truck to cold storage facilities at Littleton, New Hampshire. The assistance of the drill crew and personnel of Task Force 43, who together performed most of this work, is gratefully acknowledged. The drill hole at "Old Byrd" (drilled in the 19571958 summer) is still accessible for temperature and deformation measurements above 200 m. Originally 14.6 cm in diameter and 309 m deep, this hole has closed off to less than 6.0 cm at 200 m. Closure rates in the top 200 m have remained essentially linear at these lower stresses, in marked contrast to the accelerating closure rates observed at the higher stresses below 200 M.
Results of seven years' measurements along two 10-km-long accumulation-stake lines that traverse the undulating snow surface around Byrd Station show that the snow has been accumulating at the rate of
References Langway, C. C., Jr., H. Oeschger, B. Alder, and A. Renaud. 1965. Sampling polar ice for radiocarbon dating. Nature, 206 (4983): 500-501. Oeschger, H., B. Alder, H. Loosli, and C. C. Langway, Jr. 1966. Radiocarbon dating of ice. Earth and Planetary Science Letters, 1: 49-54. Oeschger, H., B. Alder, and C. C. Langway, Jr. 1967. An in situ gas-extraction system to radiocarbon date glacier ice. Journal of Glaciology, 6(48) : 939-942. Ueda, H. T., and B. L. Hansen. 1967. Installation of deepcore drilling equipment at Byrd Station (1966-1967). Antarctic Journal of the U.S., 11(4): 120-121.
Ueda, H. T., and D. E. Garfield. 1968. Deep-core drilling program at Byrd Station (1967-1968). Antarctic Journal of the U.S.,III (4): 111-112.
Core Studies and Related Glaciological Investigations
5cm
ANTHONY J . GOW U. S. Army Cold Regions Research and Engineering Laboratory Participation in the 1968-1969 antarctic field season was limited to processing cores from the deep drill hole at Byrd Station, conducting further measurements of closure in the 309-rn drill hole at the old Byrd Station, and remeasuring accumulation at snow stakes around Byrd Station. Approximately half of the total length of ice cores (1,100 m) from the deep drill hole was packed and returned to the United States aboard USN Wyandot. The shipment reached Davisville, Rhode Island, on March 15, 1969, and the cores were then 124
Dirt-ice bands and a fragment of granite in core from 2,162-rn depth (2 m from bottom of ice sheet) at Byrd Station.
ANTARCTIC JOURNAL
10 to I cm of water equivalent annually. This is approximately 50 percent less than that measured at "Old Byrd" during the IGY. Depressions are still accumulating appreciably more snow than the crests of these undulations. Surface elevations were remeasured to determine if these undulations are actually migrating, but the results were inconclusive. Core studies in the laboratory at Hanover, New Hampshire, show that the cores are still relaxing (manifested by a density decrease with time) and that expansion due primarily to crack formation has been greatest (0.6 percent in 16 mon t hs) in brittle ice from between 800- and 900-m depth. Deeper bubblefree ice shows little evidence of brittle cracking; this lack of cracks is attributed to the strongly oriented crystal structure of the ice, which is apparently able to dissipate much of the strain associated with expansion upon release from high confining pressures. The disappearance of air bubbles in the ice between 900 and 1,100 m, after bubble diameters have decreased to about 0.15 mm, suggests attainment of a critical diameter of bubble, which at the prevailing overburden pressures (80 to 100 bars between 900 and 1,100 m) encourages air molecules to diffuse into the ice, possiLly as clathrate hydrates of air. Bubble-like inclusions of air are now appearing in some abundance in ice originally devoid of all trace of bubbles.
MACARONI POINT 6255 •S LAND ERUPTION CENTER 1967 IF
CHILEAN BASE MOUNT X POND 542 In BLACK GLACIER
•ARGENTINE BASE 1;
BAILY HEAD BRITISH BASE .
CRATER LAKE 63O0S
. MOUNT KIRKWOOD KWOOD 460
62
Fig. 1. Deception Island.
UNNAMED GLACIER GI DECEPTION ISLAND 0 - 00
Glaciology and Glacial Geology on Deception Island
800 EQUILIBRIUM 900 LINE
JEAN-ROLAND KLAY'
and
1000
OLAV ORHEIM2
DO
Institute of Polar Studies The Ohio State University
Deception Island (63°S. 60°10'W.) is a circular volcanic caldera with a radius of about 6 km (Fig. 1). In November and December 1967, a series of explosive volcanic eruptions occurred NNhich blanketed part of the island with volcanic material. The effects of this eruption on the glaciers and geomorphology were investigated during January and February 1969 by a three-man party from the Institute of Polar Studies. Through stratigraphic studies (carried out under glaciological investigations conducted by Orheirn, measurements of snow thickness and ablation, and meteorological observations, the mass balance was determined for an unnamed valley glacier (G 1 in Fig. 1, Fig. 2). The ash layer from the 1967 eruption (from ' Glacial Geology.
'Glaciology.
July—August 1969
00
DIVIDE
100 0
I
300 0
500m
I I
1500 ft
CONTOUR INTERVAL 100 ft Fig. 2. Unnamed glacier G 1, Deception Island. Based on Directory of Overseas Survey map of Deception Island, scale 1:25,000. The circles and the numbers refer to the stakes.
1-2 cm thick in the accumulation area) was extremely well marked and will be an excellent reference horizon for future stratigraphic studies. In the abla125
