PRELIMINARY REPORT ON THE 1967-68 RENNICK GLACIER GEOLOGICAL SURVEY EXPEDITION, NORTHERN VICTORIA LAND, ANTARCTICA.

From a geological point of view the trip was a very successful one. Its success was due in no small way to the interest shown by the filed men and to the efficient and enthusiastic way in which they handled the logistics side of the expedition.

This season's geology expedition tackled all the above problems and it is considered that the area was covered in sufficient detail to enable reliable conclusions on most of the above problems to be made after examination of samples and evaluation of field data has been completed.

(1)	Several good sections through rocks of the Bowers Group were examined between the Quartzite Ranges and the Carryer Glacier but descriptions of Bowers Group rocks north of the Carryer Glaciers in the Explorers Range were severely restricted as access to the exposed rock by a ground party was impossible due to heavy crevassing in the tributary glaciers and the generally rugged nature of the terrain. It is considered that further work in this part of the Bowers Mountain would be impracticable without helicopter support The contact between the Robertson Bay Group and the Bowers Group was traced for 90 miles mostly between close limits and although the contact itself was never found exposed, it can be interpreted either as a conformable or a fault contact. The latter is preferred. Field relationships indicate that the Bowers Group is younger than the Robertson Bay Group. Detailed mapping within the Bowers Group will allow subdivisiion of these rocks into at least three major formations one of these being the previously recognised Camp Ridge Quartzite. A huge thickness of conglomerates in excess of 20,000 feet thick, of varying lithologies was also mapped near the base of the exposed Bowers Group sequence. Several facies variations along the strike were also mapped but these will be dealt with in some detail in a more comprehensive report at present in preparation. In addition a good collection of Archaeocyathid corals, of probable Cambrian age, was obtained from a reef-like limestone body near the top of the exposed Bowers Group sequence. Bowers Group rocks have been folded into a broad synclinal fold and faulted against Rennick Schist and Beacon Group to the west.
(2)	Two similar granite plutons (one in the Narazumi Range, the other in the Freyberg Mountains) and their relationships to the biotite schists which they intrude were also examined. The biotite schist can probably be correlated with the Rennick Schist but the nature of the relationship of this schist to the Bowers or Robertson Bay Groups will have to await a more detailed laboratory analysis. The results of the latter investigation will be submitted in a more detailed report.page 5
(3)	Several outcrops of Beacon Group sandstones and Ferrar Group dolerites were also examined and a good macrofloral collection wasobtained from carbonaceous sandstones at Takrouna Bluff in the loner Canham Glacier. Perfectly preserved leaves and stems were obtained and several species appear to be represented. It can also be shown conclusively that the Beacon sandstones and the Camp Ridge Quartzite of the Boners Group are separated by a considerable interval in time. The Quartzites are stratigraphically older than the Cambrian archaeocyathid limestone and the Beacon sandstones in Northern Victoria Land have a mid Mesozoic age. Strong structural discordancy between these two rock types was also found on the west side of Leitch Massif where non-folded gently west dipping Beacon sediments are in probable fault contact with folded steeply dipping Camp Ridge Quartzite.
(4)	The coarse grained quartz porphyries and rhyolites at Gallipoli Heights occur adjacent to a large granite pluton in the Freyberg Range but no direct contacts were found exposed. A fault contact is considered to be most likely but a genetic relationship between the acid volcanics and the granite pluton is strongly suggested despite the more recent faulting.
(5)	A number of processes contribute towards present day weathering phenomena. Of these, salt weathering is probably the most effective especially on crystalline rocks. A number, of types of salts were collected for analysis. In addition, wind abrasion, front heaving and running water were observed to have minor effects on slope erosion. The glaciers themselves do not appear to be actively eroding. Detailed meteorological observations were made daily and frequently twice daily, the information being radioed back to Scott Base on normal radio schedules. The meteorological data was passed on from Scott Base to the McMurdo meteorological office. A detailed analysis of meteorological data will be submitted to R.D.R.C., when completed. A limited number of biological observations were also made. These include reports of bird sightings and descriptions of mosses and lichens and will be summarised in due course. Approximately 170 rock samples wore also collected including large samples of igneous and metasedimentary rocks for potassium-argon age determinations.