mid-December, a replacement helicopter arrived, mountains. Attempts also were made to isolate air- and the investigations proceeded on the scale origi- borne plant propagules at the base camp. nally planned, except for delays caused by the Paleomagnetic investigations were undertaken by weather, with geophysical studies being conducted in Washington University (St. Louis) to determine the the third aircraft. From November 1, 1966, until magnetic-pole positions indicated by rocks of Juras- January 25, 1967, when the base camp was evacu- sic age. Comparisons of these positions with those ated, flights could be made on only 27 days. On those exhibited by rocks of the same age collected in other days, operations were carried out around the clock antarctic regions will aid in elucidating the tectonic if weather permitted. history of the Continent. The topographic program was carried out by the Scientific Programs U.S. Geological Survey to establish control for aerial Geological studies were conducted by Texas photographic mapping of this part of Marie Byrd Technological College and the University of Minne- Land and to determine the locations of some gravity sota in all mountains of the area except the stations in cooperation with the geophysical pro- northernmost part of the Ford Ranges. A major ob- gram. (Because the topographic program involved jective of this work was to determine if the Fosdick work in other parts of Antarctica, discussion of the Mountains are made up of very old rocks, perhaps work done in Marie Byrd Land is included in the of the basement complex, or if they are part of the general report, which is presented on page 118.) plutonic masses which are distributed with some The geophysical investigations consisted of mak- regularity throughout the Ford Ranges. ing a 6,500-km aeromagnetic survey and obtaining Botanical studies, which were conducted by the ice-thickness, magnetic, and gravity measurements. Institute of Polar Studies, Ohio State University, It was carried out by the Geophysical and Polar consisted primarily of the collection of algae, li- Research Center, University of Wisconsin. chens, and mosses and the recording of rock-sur- These programs are described in the following face, subsurface, and water temperatures in the articles by the investigators who conducted them.

Geology of the Marie Byrd Land Coastal minimum thickness of 4,600 m. The section is com- prised of a monotonous sequence of nonfossiliferous Sector of West Antarctica quartzites and graywackes and minor beds of quartz- ose shale. During a period of orogeny, these sedi- F. ALTON WADE ments were intensely folded and intruded by huge Department of Geosciences plutons of granodiorite and granite. Numerous basic Texas Technological College dikes and irregular plutons cut the granitoid intru- sives and metasediments. The axes of the major folds trend roughly west-northwest and plunge gently Between October 25 and December 30, 1966, a in the same direction. Radiometric age determi- geological field party from Texas Technological Col- nations made of granites and a biotite schist which lege studied and mapped bedrock exposures in an were collected in 1940 by the writer in the Rocke- area of approximately 50,000 square km in the feller Mountains place the time of the orogeny in western portion of the Marie Byrd Land coastal sec- the Cretaceous period. Extrusions of olivine basalts tor. The four-man group was accompanied by Dr. and associated tuffs occurred in the northern portion L. V. Klimov, Soviet exchange scientist, whose con- of the Ford Ranges during the Tertiary and may tributions to our geologic interpretations are grate- have continued into the Recent. fully acknowledged. One anomalous unit was found in the Ford The investigations were confined largely to the Ranges. It is a roughly rectangular block 100 km Ford Ranges and the mountains of Edward VII long and 15 km wide. It includes Mitchell Peak, Peninsula. Portions of these ranges had been investi- Birchall Peaks, the Fosdick Mountains, and the gated by the writer in 1934 and 1940, by L. A. Griffith Nunataks. It is composed of gneisses and Warner and C. F. Passel in 1940, and by G. A. schists which represent intensely folded and grani- Doumani in 1959. These previously surveyed seg- tized sediments. Two explanations are given: ments have now been tied together, completing the (I) A higher degree of metamorphism occurred reconnaissance survey of western Marie Byrd Land. in the area of the anomalous unit, thereby producing With one possible exception, the oldest rocks in gneisses and schists from the same type of metasedi- the area are a sequence of metasediments with a ments that are widely distributed to the south and

July-August, 1967 93 west. In addition, localized metasomatic emanations toward the middle, traveling in separate helicopters. occurred, causing considerable migmatization and On these flights, biologists, a paleomagnetist, or a granitization. geophysicist accompanied the geologist. Dr. L. V. (2) This elongated segment of the ranges is an Klimov, Soviet exchange scientist, also worked with upfaulted block of the basement complex from the group on the Ruppert Coast; valuable exchanges which the overlying, younger rocks have been re- of ideas on geological questions resulted from his moved by erosion. The schists and gneisses are thus presence. the metamorphosed and granitized rocks of an older On many days, bad weather either prevented heli- sedimentary sequence. copter flights or caused them to be terminated pre- The writer favors the latter explanation. Because maturely. Nevertheless, due to the great mobility of the importance of this unit in the overall interpre- afforded by the aircraft, all significant outcrops in tation of the geology of the Marie Byrd Land coast- the area were visited. Approximately 140 rock spec- al sector, detailed petrologic, structural, and geophy- imens (mainly gneisses, metavolcanics, metasedi- sical investigations are recommended. ments, and granites) were collected, structural data The relationships of this portion of West Antarc- were obtained, and photographs were taken of sev- tica to the rest of the Continent have not been es- eral well-exposed contacts. Considerable time was tablished. It is hoped that the continuation of the spent in the area of Mount Gray, where the largest Marie Byrd Land Survey, scheduled for 1967-1968, group of outcrops on the Ruppert Coast occurs. The will provide the information necessary to solve the results of these investigations are now being evalu- problem. ated at the University of Wisconsin. Age determi- nations and other studies of the rock collections should elucidate the relationship of this region to the rest of West Antarctica. Geology of the Ruppert Coast On December 30, a successful reconnaissance flight was made to the Kohler Range to establish a campsite near some nunataks where both massive BERNHARD SPORLI and (possibly granitic) and layered (possibly sedimen- CAMPBELL CRADDOCK2 tary) rocks are exposed. A group of four scientists, Department of Geology and Geophysics including the writers, were to have spent about two weeks in this area with motor toboggans after work of Minnesota University on the Ruppert Coast was completed, but attempts to place this party in the field on January 18 and 24 The field work undertaken by the University of were unsuccessful because of very bad weather in Minnesota party in the 1966-1967 season was part the landing area. of the Marie Byrd Land Survey, which was to have operated from several base camps in the coastal areas of West Antarctica. Because various circum- stances prevented this traverse from proceeding beyond the first camp, the outcrops originally sched- Paleomagnetic Investigations in uled for study could not be reached. Thus it was Marie Byrd Land decided to concentrate on the Ruppert Coast be- tween Mount Shirley and Cape Burks, an area LeROY SCHARON and THOMAS EARLY which had not been studied previously and which lay within range of the helicopters based at Camp Department of Earth Sciences No. 1 in the Ford Ranges. The field work was done Washington University, St. Louis between December 30, 1966, and January 18, 1967. Because outcrops in this area are isolated nuna- The value of paleomagnetic investigations in de- taks or groups of peaks separated by large, rather termining large-scale tectonic movements has been strongly crevassed glaciers, transportation by heli- demonstrated in various parts of the world. A few copters is essential. During the initial reconnais- such investigations have been conducted in Antarc- sance, the two party members visited exposures to- tica, but the tectonic history of the Continent is yet to gether, then each worked from one end of the region be fully established. Paleomagneti& data obtained by other investiga- Now Project Associate, University of Wisconsin. tors from Cretaceous and younger rocks in the 2 Now Professor of Geology, University of Wisconsin shield area of East Antarctica have established

94 ANTARCTIC JOURNAL