Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/54

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A. W. H0WITT ON THE PHYSICAL GEOGRAPHY AND

about 80 feet above the river, and they present almost the same tri- plicate appearance of compact beds with either porphyritic ortho- clase and quartz crystals, or quartz crystals alone, in a compact base, and one well-marked bed of nodular and geodic felstone. The re- markable persistence of these well-marked divisions over so large an area leads me to regard this as a contemporaneous sheet.

Dykes and masses of diorite and of other basic igneous rocks, which I have not as yet been able satisfactorily to determine, of porphy- ritic and quartziferous felstones, have penetrated, cut off, and gene- rally disturbed the nearly vertical Tabberabbera shales, but do not seem to have risen up through the Iguana-Creek beds.

In Maximilian Creek, about 16 miles to the westward of Iguana Creek, which I lately visited in company with Mr. Reginald Murray, of the Geological Survey of Victoria, I found the series of strata shown in the subjoined sketch (fig. 9), which has been condensed from several natural sections.

Fig. 9. — Diagram Section of Group of Beds at Maximilian Creek.

a. Quartzite.

6. Coarse quartz and slate conglome- rate.

c. Coarse reddish sandstones with pebble bands.

d. Porphyritic, quartziferous,

and concretionary felstones.

e. Shales.

/. Quartz conglomerates. g. Sandstones with pebbles.

I need only point out that, making due allowance for slight litho- logical differences, we have here identically the same series of rocks, both sedimentary and igneous, as that seen at Tabberabbera and the Mitchell River near Cobbannah Creek.

In following the northern edge of the Iguana-Creek beds no break is found to the westward, and they appear continuous with those at Maximilian Creek.

In the absence of any palseontological evidence the indications afforded by the groups of strata themselves are stratigraphically so strong that I have no hesitation in regarding the Maximilian-Creek