A description of the floating Ross ice shelf in Antarctica, determined from miscellaneous studies between 1957 and I960, is provided by contoured maps giving values of ice thickness, ocean floor depth, surface snow density, average annual temperature, and average annual snow accumulation. The low surface densities and low average annual surface temperatures encountered in the central part of the shelf are explained by meteorological parameters. The thickness of the ice varies from about 700 meters in the southeastern area of the shelf to about 250 meters near the barrier edge, and it is demonstrated from theoretical strain values for floating ice that the main portion of the shelf must be under abnormally large horizontal stresses which prevent the ice from thinning more rapidly, thus accounting for its presence over such a large area. Snow densities at 40 meters depth, derived from an empirical relation between seismic refraction velocities and densities, vary widely over the shelf areas, and these differences can be explained in part by variations in the strain rates. The horizontal velocity components of the ice particles are obtained from the amount of accumulation and the area of the ‘snowshed,’ on the assumption that elevations are not changing in time. In order for these inferred velocities to conform to observed values near the shelf barrier, considerable melting is required at the ice‐water boundary at the bottom of the shelf. This melting is confirmed by local data and is shown to increase from east to west. Vertical velocities of ice particles with respect to the surface are determined from snow accumulation and strain rates. These velocity components are combined in a numerical‐integration method to allow the ice particle paths to be followed forward or backward in time or in space. The method is illustrated by reference to the area of Little America station, where a 250‐meter hole was drilled in 1957. Ice cores from this hole, which include three large ash layers, have a maximum age of about 4500 years.

A survey of the ocean tide in the southern Ross Sea was done by measuring tidal variations of gravity at nine locations on the floating Ross Ice Shelf. Tidal water level fluctuations were calculated from recordings between 29 days and 58 days long of the periodic variation in gravity on the ice shelf surface that is caused by tidal changes in elevation and water mass. Conventional tide gauge measurements from McMurdo Sound were included in the survey. The data indicate that the Ross Sea tide is principally diurnal. Along the northern margin of the Ross Ice Shelf the tropic (diurnal spring) tidal range is between I m and 1« m. The range increases to more than 2 m in the southernmost part of the Ross Sea. It is more than 3 times larger than the equatorial (diurnal neap) tidal range. Amplitudes of the principal diurnal constituents Kl Pl and 01 are apparently magnified by a condition of diurnal resonance in the Ross Sea. This would be expected because wavelengths of the diurnal harmonic constituents are approximately 4 times the length of the Ross Sea in the direction of propagation. The diurnal constituent amplitudes also appear to vary proportionally with the fourth root of the water depth as predicted from the theory of long wave propagation in a canal. Semidiurnal constituents Me, S2, and N2 have small amplitudes and appear to progress clockwise around amphidromes located beneath the northwestern part of the Ross Ice Shelf. 6 kw diesel generators. An attendant at each site was responsible for maintenance of the generator and heating stove, veri-fying that the gravimeter was operating normafly, and placing calibration and hourly time signals on the record. PREVIOUS WORK The early Antarctic expeditions traveled by ship, and naturally made observations of the ocean tide. Near the turn of the century, four British expeditions made tidal observations in the Ross Sea at (Table 1) Cape Adare [Bernacchi, 1901], Hut Point [Darwin, 1908], Cape Royds [Shackelton, 1909], and Cape Evans [Doodson, 1924]. The Cape Adare observations were made near 70 ø5 I'S, 170 ø 10'E for 1 day only and thus cannot be analyzed for harmonic constituents. The tide appeared to be diurnal and had a 1 m range at the time of a solar eclipse. This is the only published measurement of the tide in the northern Ross Sea. The remaining three locations are all on McMurdo Sound (near McM in Figure 1) where major United States and New Zealand base camps are situated, and where lengthy, higher quality records of the tide have been made since 1957.

able values of specific storage, barometric increment in the aquifer, V a is the total volume efficiency, porosity, and matrix bulk modulus were of that increment, V m is the volume of the solid calculated, but the accuracy of these values is portion, and V w is the volume of the pore space. limited by the imprecise measurements of water level and barometric pressure and the possibility of leakage from imperfectly confined aquifers.

The ocean tide in the southern Ross Sea is principally diurnal. The tropic tide range (double amplitude) is between 1 and 2 meters, depending on the location, and is closely related to the local water-layer thickness. The range of the tropic tide is more than three times the range of the equatorial tide. Cotidal and coamplitude charts were made for the largest diurnal constituents, K 1 and O 1 and a provisional cotidal map was made for the semidiurnal constituent M 2 . The amplitudes of the diurnal tide constituents are larger in the Ross Sea than in the adjacent southern Pacific Ocean, indicating the existence of a diurnal resonance related to the shape and depth of the sea. Waves related to ocean swell propagate into the ice-covered region from the northern Ross Sea. These waves have amplitudes near 1 centimeter, and periods in the range 1 to 15 minutes. The speed at which these waves travel is successfully predicted by flexural wave theory.

Flexural waves related to the ocean swell are identified more than 600 km from the open sea in the Ross Ice Shelf, Antarctica, where the ice cover is in places more than 500 m thick. An equation relating the power spectra of the flexural wave and the ocean swell is derived, based on the continuity of pressure in the fluid layer across the ice front. Correcting for the effect of the ice, the power spectrum of the wave in the ice compares to that of the ocean swell elsewhere in the Pacific Ocean.