was generally good in all areas, being observed as 10 nautical miles 

 or over 67 percent of the time in the Ross Sea area, 90,5 percent of 

 the time in the Cape Colbeck to Palmer Peninsiila area, and 72,5 percent 

 of the time in the Weddell Sea area. 



Rain or drizzle was not observed during the ATKA's stay in the 

 Antarctic, but snow showers were reported 12 percent of the time in 

 the Ross Sea area and 1,8 percent of the time in the Weddell Sea areaj 

 snow showers were not observed in the Cape Colbeck to Palmer Peninsula 

 area. Snow was observed 23,6 percent of the time in the Ross Sea, 8 

 percent in the Cape Colbeck to Palmer Peninsula area, and 18.7 percent 

 in the Weddell Sea area. Very little fog was noted in any of the areas, 

 light fog being observed only U»5 percent of the time in the Rors Sea 

 and 1,2 percent in tho Weddell Sea area. Fog was not observed in the 

 intermediate area between Cape Colbeck and the Palmer Peninsula, The 

 maximum observed barometric pressure occurred on 9 February in the upper 

 Weddell Sea (996,0 millibars )j the lowest barometric reading was made 

 pn 17 February at Atka Bay (971,8 millibars). 



It wi3J. be noted from the above summary of weather conditions en- 

 countered during the ATKA's brief stay in the Antarctic, that opportunities 

 for sun observations for periods of 2I4. hours or more are extremely limited, 

 bright clear days being the exception. The high percentage of low over- 

 cast is largely responsible for this condition, plus frequent snow and 

 snow showers. Visibility at sea level is good and fog is not a problem, 

 but an unobscured view of the sun is a rare phenomenon during the summer 

 months in the Ross Sea, Cape Colbeck to Palmer Peninsula, and Weddell 

 Sea areas. 



D, Bottom Sediments 



1, General 



There are three zones of bottom sediment types surrounding the 

 Antarctic Continent, according to the most recent information. The 

 deeper parts of the surrounding oceans (outer zone) have sediments of 

 Globigerina ooze which intergrade with diatomaceous ooze in the inter- 

 mediate zone as one nears the' approaches to the continent. The inner- 

 most zone is a wide belt from 100 to 500 miles wide ^ich extends out 

 from the continental borders at least as far as the 3,500 meter line. 

 The bottom sediments of tho innermost zone are of terrigenous origin 

 and are referred to as glacial marine deposits. The sediments in this 

 zone have originated mainly from the adjoining land and have been carried 

 to thoir present position by rafting ice and icebergs. Subsequent to 

 their deposition, there has been little change in the physical or 

 chemical characteristics of the sediments, or in their position. 



U7 



