Part I of this paper was published in the April, 1947, issue of the Transactions pages 162 to 170.The principal questions upon which interest has centered are the origin of the shelf ice, the natural causes which have maintained it almost unchanged over the years, the causes and directions of its movement, and the causes for the persistence of the various breaks along the Barrier and of deeply crevassed areas at various points over the sheet.As a result of the scientific work of the Byrd Antarctic Expedition II from 1933 to 1935, information on most of these points is now available for about five thousand square miles of the Ross Shelf Ice. Using the geophysical equipment described in the first part of this paper, the author and his associates took soundings over an area extending from the Barrier south to latitude 80°07′ and in an east‐west direction from Kainan Bay to Discovery Inlet.Attempts to measure the rate of accretion of the shelf ice by snow gauges of various sorts must be regarded as unreliable. Widely as the records vary, it is quite apparent from the observations that the net accumulation on the surface of the ice in regions 100 miles or more from open water is only a small per cent of that occurring within 50 miles or less of open water.The two most important processes whereby the density of the shelf ice is changed are: First, settling, either slow, or rapid through snow tremors; and, second, recrystallization. Although the density at the surface may be only one or two tenths, the average for the first five feet will be about five‐tenths; but even at considerable depths the density is always appreciably less than that of solid ice.A modified McComb‐Romberg seismograph was used as a tilt meter, and a recurrent tilting of the ice was observed, having a period of about 25 hours and in the proper phase with the moon for a tidal effect. While it is impossible to determine the magnitude of the tide by this method, it is not unreasonable to suppose that a tide at least equal to that at Ross Island, namely, three feet, exists at the Bay of Whales.Triangulations made in 1934 on some of the markers established in 1929, combined with accurate fixes from star sights of the position of Little America, provide the data from which the shift in position of the ice surrounding the Bay of Whales during this five‐year period was determined.The contour map presented in the preceding Part is now extended to several thousand square miles. Most of the seismic records show marked stratification of the bottom and two cross sections (Figs. 12 and 13) have been constructed. The cross sections of the Ross Shelf Ice, one across the Bay of Whales to Roosevelt Island, and the other south into the shelf ice east of Lindbergh Inlet, throw a great deal of light upon the condition of equilibrium that exists today.A current of from one to three knots enters Okuma Bay and moves in a southwesterly direction, partly along and partly under the ice at Kainan Bay. It enters the Bay of Whales along the Barrier or emerges from under the shelf Ice on the east side of the Bay, particularly through Eleanor Boiling Bight, crosses the Bay in a southwesterly direction, and again goes beneath the ice along the west side of the Bay. The current then travels west under the ice past or south of Lindbergh Inlet and out from under the ice in a northwesterly direction through Discovery Inlet.The current underneath the ice where it projects out over the moraine causes a maximum amount of melting to occur along this path, thereby causing the major portion of the glacial material being carried by the shelf ice to be deposited on the forward edge of the moraine. This process is sufficient in itself to account for the origin of the Ross Shelf Ice.The present seismic measurements of the Ross Shelf Ice have provided the first real information,on its thickness, the thickness of the water layer under the floating portion, the contour of the bottom under the ice, the existence of large moraines and the contour of the undisturbed rock surface below. It has been shown that a much larger proportion of the shelf ice is actually or practically in contact with the bottom than has hitherto been suspected. These data have provided the answers to many of our questions relative to the origin of the shelf ice and the persistence of its characteristic features.