320 Cc. F. LASERON. 
At Yalwal Creek the Devonian consist nearly wholly of 
quartzite, and dip to the north-west. As no marine fossils 
had ever been found in these beds, considerable search was 
made, but for a long time without success. Boulders con- 
taining Devonian fossils were found at last in Yalwal Creek, 
and eventually in situ at the junction of Yalwal and 
Ettrema Creeks. At this spot the folding is very sym- 
metrical, regular anticlines and synclines being formed. 
The strike is invariably N.E. and S8.W. The rocks consist 
of quartzites, sandstones and grits containing several fossil- 
iferous horizons, which consist of bands of sandstone up to 3 
feet in thickness, practically made up of the remains of 
pelechypods. 
Mr. Dun identified the following genera—Allorisma ? 
Sphenotus, Leptodomus, Pterinea, and Goniophora? No 
other fossils at all occur with the exception of several 
specimens of Lepidcdendron. The shells are unfortunately 
very badly preserved, and no specimens perfect enough to 
describe were obtained. The internal casts of the specimens 
were often encrusted with minute doubly terminated quartz 
crystals, of which there was usually a cluster of somewhat 
larger ones on the beak. There is an absence of pebbles 
of any sort among these strata. 
Following the course of Yalwal Creek above its junction 
with Ettrema Creek for about a mile, a very interesting 
section occurs. A high cliff runs back at right angles to 
the creek, sectioning the hillside. The strata at its base 
are quite vertical and even inverted, while about half way 
up the face they are sharply bent to the right, until they 
are past the horizontal. In the face of the cliff, on closer 
examination, it is seen that the various layers have stood 
the enormous strain unevenly. Some of the bands have 
yielded, producing a number of miniature thrust faults. 
The appearance of the fold suggests that it was just on the 
