110 
NOTES ON THE GEOLOGY OF THE NINETY=MILE 
DESERT. 
By Epwarp VINCENT CLARK, B.Sc. 
[Read April 14, 1896.] 
Prats, I. 
The geology of the area enclosed between the River Murray 
on the north and west, and the Victorian frontier on the east, 
is little known, with the exception of the more southerly portion, 
where the Eocene beds of the Mount Gambier District are found. 
The object of this paper is to bring into notice several Tertiary 
deposits occurring in or near the Ninety-Mile Desert. 
The Mount Gambier beds are fairly well known, and have 
frequent outcrops from Kybybolite, where they have an altitude 
of about 300 feet, and Narracoorte, 279 feet, to MacDonnell 
Bay, where they pass below sea level, thus having a dip of about 
three feet per mile, as Kybybolite—according to the Rev. 
Tenison-Woods, the most northerly point in this district having 
an Eocene outcrop—is about 100 miles from the coast. 
A well sunk at Bordertown by the Railway authorities re- 
vealed a polyzoal limestone some distance below the surface, and 
a short time ago I obtained several fossils from various wells, five 
or six miles south of Bordertown. The matrix of the bed is 
very similar to that of the Mount Gambier Eocene, being almost 
a pure limestone, composed mostly of broken pieces of polyzoa, 
with a few large fossils. This limestone forms the base of the 
wells, which are about 70 feet deep, but as, unluckily, I was 
not present at the. digging of any well, I am unable to say how 
near to the surface these beds extend. As the Bordertown Rail- 
way Station is 268 feet above sea level, these beds have an alti- 
tude of about 200 feet, or perhaps more. According to the dip, 
above mentioned, of the Mount Gambier beds, they should have 
an altitude of about 400 feet, but although they may originally 
have had this altitude and have been worn down before the de- 
position of the present surface material, this is not likely. Still, 
considering the similarity in the lithological features of the bed 
here and further south, there is no reason to doubt the continuity 
of the Bordertown bed, and the Eocenes of Narracoorte and 
Mount Gambier. 
The fossils found at Bordertown were not numerous, either as 
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