92 
The Queensland Naturalist. 
Sept., 1924 
A FEW NOTES ON THE GEOLOGY AND 
PHYSIOGRAPHY OF MORETON ISLAND. 
By Dr. E. 0. Marks, B.A., B.E. 
Our Easter excursion to Moreton Island Avould make 
a geolog'ist anxious for Ihe examination of solid rocks, 
symi)athise with the walrus and the carpenter at se(un^' 
such (piantities of sand. Solid rocks occur at Cape More- 
ton, hut Cowan Cowan was too far away to allow of a 
visit to this, and during- our trip we saAV no solid rock, 
only sand. In spite of this the excursion Avas of consid- 
erable geological interest, for Ave were examining what 
must be among the highest sand-dunes in the Avorid- 
Mt. Tempest, the highest point of the island, is. according 
to the surA’ey map. 910 feet high, and is all sand, or at 
any rate there is no indication of any solid rock on the 
surface so far as we could see. 
The topography of the island is very interesting, the 
hills being A'ariable in outline and sometimes very steep; 
the holloAvs both V-shaped valleys and Avide basins. 
iSeen from the summits the V valleys give one the 
impression of being the result of denudation, but a closer 
examinatioji shows this not to be the ease, for there is 
no evidence in the valley bottoms of anything in the 
natnia* of a stream, Avhile many of the A'all'eys are 1)1 ind. 
haA'ing no outlet. There AA'as no sign of water liaAung 
ever collected, and the whole island, so far as Ave saw it, 
ap])ears to act like a gigantic sponge absorbing all the 
rain falling on it. This apparently oozes out to the mauA' 
SAvamps near sea leAml at the margin of the island. At 
loAv tide the Avater oozing from the beach is in many 
places fresh or only slightly brackish. That the form of 
the hills is frequently unlike the usual rounded dune is 
probably duo to the Au^getation anchoring irregularly 
Avhat otherwise Avould ha\'e been drifting sand. 
HcA'eral loose fragments of a coarse silicibed sand- 
stone were found, mostly haA'ing one side somewhat 
rounded. It Avas suggested that these had probal)Iy been 
brought there' by the aborigines for grinding fern roots. 
Vo ])ossihle local origin for them Avas obseiwed and they 
were formed of a much coarser sand than the sand 
coin])r>sing the island. 
A A'isit Avas ])aid to the sandy desert, an area of bare 
sand, about half a mile S(piare, behind Tangaloorna light- 
house. This is not('d for the ocenrenee of fulgurites, 
some of which Ave Avere fortunate enough in obtaining. 
