(b) Cape Bird

The excursion to Cape Bird (40 kms north of Cape Barne) proved more rewarding than expected. A number of fossils have been recorded here previously by Speden (1962). Belonging to the Scallop Hill Formation, they are presumed to belong to at least the Penultimate Interglacial, and have since been uplifted to at least 600 m above sea level. They are now found within moraines being deposited by the Mt. Bird ice cap. A search throughout this area revealed many of the fragmented pectens (Chlamys andersoni) and bryozoans collected previously, together with the rarer solitary coral Gardineria antarctica and a whale bone about six inches long.

Traversing along the coastline to Cape Bird B, twenty-three successively raised beaches were discovered, and considerable time was spent in measuring these features along a number of parallel traverse lines. The formation of the beaches on this spit is considered to have formed by a current flowing around Cape Bird from the east, eroding and carrying material along the coast (probably by longshore drift) until it reaches the principal northward current of McMurdo page 17 Sound. Here the gravels have been deposited and under favourable weather conditions the moving ice flows express the surface currents exceedingly well.

The highest of the sequential raised beaches was only about 6.9 m above sea level, but raised beaches found at other localities along the coast range up to 11.4 m a. s. l.. A bench found between 36 m and 39 m a. s. l. is attributed as being of Last Interglacial age.

A one day excursion was made to the more southerly region of the ice-free area at Cape Bird. Here a number of quite different volcanic rock types are exposed (Cole and Ewart 1968), and a collection was made for detailed geochemical work. Rock types include hornblende - pyroxene trachytes, olivine basalts and olivine - augite basalts. Additional features observed and described along the coastline include gravels being deposited by the ice-foot (the rim of ice along the shoreline). Samples have been obtained (in conjunction with the Waikato and Canterbury Expeditions) of soils developed on variously aged, raised beaches from the Northern Penguin Rookery to compare the effects of addition of guano to the regolith.

Dr. C. Hendy is intending to radiometrically date a number of the beaches (assuming that the penguins are rapid colonisers of ice-free areas as soon as they become available). If this dating is successful, it will enable us to determine the build-up of concentrations of major elements at the sites with respect to time. This may form an interesting chronosequence with few variables involved in the system. Such opportunities are rare.