ABSTRACT. R ecent measurements of snow acc umulation on undulat ing surfaces around " Byrd station " , Antarctica indicate that the undulations a re tending to be filled in. These resu lts are discussed in the lig ht of c urrent knowledge of the or igin and migration of such features.RESU ME. Relalion mire I' accwnulalion de la "eige el la lopographie sllperjicielle cl la statioll " By rd" , Anlarctique. D e recentes m esures d' accumu lation de la neige sur la surface ondu lee a utour de la station " Byrd", indiquent que les ondulati ons ont une tendan ce it etre comblees. Ces resu lta ts sont discutes it la lumiere de la con naissance courante de l'origin e et de la m igration d e re li es formes. STEPPED surfaces and undulations of wavelengths of 5-30 km . are now know n to characterize much of the surface of the Greenland a nd Antarctic I ce Sheets, particularl y the latter, and there has been som e speculation as to how these features might form. Nye ( 1959) for example would attribute surface waves of these dimensions (mea n amplitudes of about 20 m. ) to irregularities in the underlying bedrock, but Bader ( 196 1) believes that drifting snow is responsible for the formation of wavy surfaces in the high interior of Greenland.A fairly considerable surface relief is to be observed in the general area of new " Byrd station" , Antarctica. New " Byrd station " was constructed under the snow near the bottom of a broad depression and between it and the old " Byrd sta tion" located 10 km . to the west there are two smaller valleys. An examination of the surface in February 1 962 indicated that the valleys were accumulating much m ore snow than the crests of these undulations. In order to obtain some quantitative data on this r elationship between accumul ation a nd surface topography, two stake lines were set up, one oriented pa ra llel to the prevailing wind direction and the other normal to it. The " east-west" line, (Fig. I) comprising 21 stakes emplaced at intervals of 0·5 km. extended from the south-east corner o f the stake farm at o ld " Byrd" to a point about a kilometer north of the radio noise tower at new " Byrd station". The second line of 22 stakes was begun just to the east of the V .L.F. antenna and extended d own-wind in a southerly direction for a distance of 10·5 km . The elevati on at each stake was measured barometrically. In Figures 1 and 2 these elevations have been conve rted to absolute values based on the elevation at the gravity pier at new "Byrd station".As indicated in Figure I , the "east-west" line traversed two small valleys superimposed on a surface that sloped upward to the east. The relief along the " north-south " line of stakes (Fig. 2) differed somewhat in that it took the form of a fa irly steeply sloping surface intersected by two small steps. The impression gained in the field was that the " north-south" stakes traversed a major structural feature of the surface a nd that the undulations a long the "eastwest" line were superimposed upon this structure. However , it is diffic...

Recent measurements of snow accumulation on undulating surfaces around “Byrd station”, Antarctica indicate that the undulations are tending to be filled in. These results are discussed in the light of current knowledge of the origin and migration of such features.

ABSTR ACT. The M cMurd o I ce Shelf a nd assoc iated faun a l rem a ins were exa mined in th e vicinity of th e easternmost D a iley Isla nd. Stra tig ra phi c, petrographi c, a nd chemical compos ition studi es of cores from two holes drilled through th e ice sh elf show th a t at th ese loca tions th e sh elf is composed onl y of fr esh-wa ter ice. Althoug h cores from the d eep e r h ole possessed typi call y glacial tex tures th ro ughout, m u ch of th e ice from this part of the M cMurdo I ce Shelf may have bee n fo rmed from th e freez ing of a layer of fres h wa ter found sandwich ed b e tween shelf b o tto m and th e und erl y ing sea-water . T he existen ce of fresh wa te r under the ice shelf ca n m ost proba bl y be a ttributed to dra inage o f surface melt wa te r during the ab la tio n season. Ther e wa s no eviden ce to indi cate that this pan of th e M c Murdo I ce S helf is b e in g nourished by th e g rowth of sea ice onto its lower surface. Th e fis h rema ins fo u nd o n the ice surface were confin ed to a n a r row zone along the tide c rack and a re beli eved to have been left in t hi s vicinity by d eep di v in g seals. Th e marine in vertebra te rema in s on top of the ice are associa ted with m o ra ina l m a teria l a nd a re b el ieved to have b een incorporated into th e ice at the time of fo rma ti on of th e mora ines. R ESU ME . .NollveLle Iwniere sllr le mode de remolltee de poissoll et morailles dJossiles £lit M cM llrdo Ice Shelf, Alltarctiqlle.Le M cMurd o I ce Shelf et Ies re liquats associes de fa un e ont ete exa min es d a ns le voisin age d e l' il e la plus it l'est d es Dailey I sla nds. D es etu des stra tigraphiques , pet rog raphiqu es e t d e compositio n c himi q ue d e ca rottes provena nt d e d eux forages it trave rs le ice shel f m o nu'e nt q ue, it ces sta tio ns, le ice shelf es t co mpose uni quemen t d e g lace d ouce. Bi en q u e les ca rOttes du b as du trou de fo rage p ossed ent tout a u lo n g d es tex tures glacia ires typiques, la plus g ra nd e pa ni e de la g lace d e cette pa rtie du M cMurdo I ce S he lf a pu se form er pa r le gel d ' une strate d'eau d o u ce sa isie entre le bas d u shelf et I'eau d e m e r sous-j acent e. L 'ex istence d 'ea u douce sous le ice shelf peut le plus proba blement e lre a ltribuee a u dra inage d e l'ea u d e fu sio n superfi ciell e penda nt la saison d 'abla li on . 11 n 'y avail a UCLln e ev ide nce en faveur d' un e cro issance pa r g lace d e mer SLlr la surface infer ieure de cett e par ti e d u M cMLlrdo I ce S h elf. Les rel iqua ts d e p o isson trou ves sur la surface de la glace etai ent confines it une zon e c tro ite le long d es c reva sses de ma ree e t I'on p ense q u' il s y ont e te a ba ndonn es par d es phoques chassa nt it g ra nd e profond eLlr. L es rc1 iqua ts d ' in ve rt e bres m a rins a u sommet d e la glace sont associes a vec du mat eri el mo ra ini q ue, et 1'0n pense qu ' ils ont ete in co rpo res it la glace lors d e la fo rma tion d es lTIora in es. Z USAMM EN FASSUNG . .Neues L i...

The differential thermal method, by determining the thermal reactions undergone by a clay or shale, is a rapid means of identifying the mineral components of such materials, and because the properties of clays and shales depend largely on their mineral composition, it is at the same time a rapid method of evaluathg the properties of such materials.Differential thermal analyses are presented for the pure forms and synthetic mixtures of the common components of clays and shales, namely, kaolinite. halloysite, illite, montmorillonite, quartz, gibbsite, boehmite, diaspore. dolomite, d a t e , gypsum, organic material, pyrite, marcasite, goethite, and limonite.Differential thermal analyses are presented also for a variety of well-known types of clays, and on the basis of the thermal data for the pure components, the mineral composition is indicated. The correlation of mineral composition of clays and shales (as re5ected in the differential thermal curves) with the ceramic properties is discussed as a basis for using this thermal method to indicate the properties of such materials.Finally, differential thermal analyses are presented for sequences of samples from the pits of several operating clay products plants in order to illustrate the way in which the method can be applied in prospecting and in plant control.

The McMurdo Ice Shelf and associated faunal remains were examined in the vicinity of the easternmost Dailey Island. Stratigraphic, petrographic, and chemical composition studies of cores from two holes drilled through the ice shelf show that at these locations the shelf is composed only of fresh-water ice. Although cores from the deeper hole possessed typically glacial textures throughout, much of the ice from this part of the McMurdo Ice Shelf may have been formed from the freezing of a layer of fresh water found sandwiched between shelf bottom and the underlying sea-water. The existence of fresh water under the ice shelf can most probably be attributed to drainage of surface melt water during the ablation season. There was no evidence to indicate that this part of the McMurdo Ice Shelf is being nourished by the growth of sea ice onto its lower surface. The fish remains found on the ice surface were confined to a narrow zone along the tide crack and are believed to have been left in this vicinity by deep diving seals. The marine invertebrate remains on top of the ice are associated with morainal material and are believed to have been incorporated into the ice at the time of formation of the moraines.

Differential thermal analysis (DTA) began soon after the development of the thermocouple. It has progressed through the systematic development of better equipment and the cataloguing of typical DTA curves for a variety of materials until good technique now requires control of the composition and pressure of the furnace atmosphere as well as consideration of the thermodynamics and kinetics of the reactions involved. Although differential thermal analyses have been made for many materials, the major applications have been concerned with clay and carbonate minerals.In DTA curves for clay minerals the low-temperature endothermic loop associated with the loss of water, and the hightemperature exothermic loop accompanying the formation of new compounds, are changed in shape, temperature, and intensity by the kind of exchange cations. The midtemperature-range endothermic loop has a temperature dependence on the partial pressure of water in the furnace atmosphere.For the anhydrous normal carbonates the dissociation temperature and its dependence on the partial pressvire of CO2 are in the decreasing order Ca, Mg, Mn, Fe, and Zn. The lower temperature loop of dolomite, the reaction for which must be preceded by an internal rearrangement, is independent of the pressure of ('()•• but may be shifted to a lower temperature by prolonged fine grinding which accomplishes a similar rearrangement.

The dehydration of sodium, potassium, lithium, hydrogen, calcium, magnesium, and manganese monoionic montmorillonites (prepared with ion-exchange columns) and a vermiculite, was examined by the x-ray powder diffraction oscillating-heating method. The position and intensity of each of the first-order basal spacings were measured at intervals of 5 ~ to 10 ~ C from room temperature to 900 ~ C. Position and intensity measurements were made for the first five orders of the basal spacing of the calcium montmorillonite up to 300 ~ C and compared with computed intensities at these spacings. These data are presented as oscillating-heating x-ray diffraction diagrams showing the intensity change with temperature, with important spacing shifts indicated, and as graphs showing the change in spacing with change in temperature.Like vermiculite, calcium, magnesium, manganese, lithium, and hydrogen montmorillonite have an octahedral coordination of their exchange cation, and upon heating they also pass through two stable hydrates (ca. 14.5 A and 11.5 A). MontmoriUonites of the two larger ions, sodium and potassium, have a regular one-water-layer configuration at 12.4 A, which is distinctly different from the 11.5 A hydrate of the smaller ions.The foreshortened oxygen-oxygen approaches of the lower hydrate (11.5 A) may be accounted for by assuming that the exchange ions take up coordinate positions between silicaoxygen and water levels or, alternatively, that some of the silica tetrahedra are inverted.

Drift, evidently of Illinoian age, was deposited on St. Lawrence Island at the margin of an ice cap that covered the highlands of the Chukotka Peninsula of Siberia and spread far eastward on the continental shelf of northern Bering Sea. Underlying the drift on the northwestward part of the island are mollusk-bearing beds deposited during the Kotzebuan Transgression. A comparison of mollusk faunas from St. Lawrence Island, Chukotka Peninsula, and Kotzebue Sound suggests that the present northward flow through Bering and Anadyr Straits was reversed during the Kotzebuan Transgression. Cold arctic water penetrated southward and southwestward bringing an arctic fauna to the Gulf of Anadyr. Warmer Pacific water probably entered eastern Bering Sea, passed eastward and northeastward around eastern and northern St. Lawrence Island, and then became entrained in the southward currents that passed through Anadyr Strait.