of 13 inches. Below this, core 19 is composed of medium gray silty raud 

 to pebbly silty sand of medium low sphericity, while core 20 is composed 

 of dark greenish gray silty mud of medium low sphericity. Lithologically, 

 both cores have feldspar as their predominant mineral to the 13-inch 

 depth, but below this, rock fragments increase to equal quantity. Quartz 

 is an important constituent throughout these cores. A trace of volcanic 

 glass also is present in both, and pyrite appears as a trace from about 

 the 15-inch depth to the bottom of the cores. Above 13 inches, the 

 biological content is 25 percent or more and is sufficiently high in 

 diatoms in the surface layers for these to be classified as diatomaceous 

 oozes. Below 15 inches, the biological content is never more than 5 

 percent. The 13- to 15-inch layers of both cores appear to be a 

 transitional zone. 



c. Mineralogically and biologically the northern and southern 

 Adelaide Island cores correlate reasonably veil. The top 6 inches of 

 the Matha Strait cores correspond to the top 13 inches of the southwestern 

 cores, while the 6- to 8-inch zone of the one long northern core agrees 

 with the 13- to 15-inch transition zones of the southern ones. In addi- 

 tion, the segments below the transition zones also appear comparable. 

 Texturally, however, these two groups of cores are exactly the inverse 

 of each other. The only place they agree is in their transition zones. 

 This textural anomaly is probably dependent upon debris -carrying ice 

 reaching these localities and partially melting* 



5. Rock Samples 



a. Rock samples were collected from various islands in the 

 Antarctic. A sample of vesicular basalt was obtained from the top of 

 Scott Island (67°2VS, 179°55'W). Samples of diorite were collected 

 from Mulroy Island (71«5U»S, 9T°51'W) and a rock islet off Williams 

 Island, Thurston Peninsula (71 e 5^'S, 100°00'W). Visual identification 

 of a rock sample from Brabant Island, Palmer Peninsula (64 e 25'S, 62»17 , W), 

 appeared to be quartz-diorite. Samples from Penguin Island, Palmer 

 Peninsula (62*05* S, 57"52*w), were of volcanic origin. Lichens and 

 mosses were collected from Scott Island, Mulroy Island, Thurston 

 Peninsula, and Penguin Island. 



51 



