CHAPTER III. 
METAMORPHIC rocks (SLATES, SCHISTS, GNEISSES, &c.) OE 
UNDETERMINED AGE. 
ineral Areas— viz., Cloncurry Gold and Copper Fields, McKinlay Gold Field, Charters Towers 
and Cape Gold Fields, Gilbert and Woolgar Gold Fields, Coen Gold Field, ITormanhy and 
Marengo Gold Fields, Peak Downs Gold Field, Peak Downs Copper Field. 
LTnouan tlie area of metamorpliic rocks, of wkich the age had not been deter- 
mined when T issued my Geological Map of the Colony in 1886, has been considerably 
reduced in the present edition, it will be seen that a considerable area still remains. 
1872 Mr. R. Etheridge, E.R.S., stated* that the Broken River limestones 
(Middle Devonian), which he called “ Siluro-Devonian,” were the lowest fossiliferous 
™cks in Queensland. The late Rev. W. B. Clarke (I think, erroneously) ascribed to 
r. Etheridge the view that “nothing lower than Siluro-Devonian rock has been found 
m Queensland.” No older ybMifc have yet been discovered, but lower and older stratified 
rocks certainly exist. 
Ihe granites and syenites of Charters Towers appear to be the ultimate stage in 
e metamorphism of the series of stratified rocks described in my Report “ On the 
eo ogy and M ineral Resources of the District between Charters Towers Gold Eield 
and the Coast.”t 
^ These rocks arc older than the Burdekin Beds. They are all metamorphosed in 
greater or less degree. The metamorphism must have taken place prior to the deposi- 
th^^^ Burdekin Beds, pebbles and granules of the metamorphosed rocks forming 
e material of which the conglomerates of the latter series are built up. 
^ These once horizontal beds are now thrown into broad folds, and probably do not 
ccupy more than one-fourth of the surface over which they were deposited. The 
Ta 1 ed rocks occur to the north and west of Charters Towers. They consist of 
qnar zites, slates, and shales. The slates do not differ from the shales in mineral 
mainly silicate of alumina, with a high percentage of peroxide of iron — 
simply in being intersected by cleavage planes. Both the slates and the greywackes 
as a m^le, highly impregnated with iron, being in places “ iron-masked” to such a 
^ gree that they might almost be taken for weathered clay-band ironstones, 
^^ecasionally , where the greywackes are fresh and contain little iron, they somewhat 
Corelli e blue limestone, while their joint- surfaces are often coated with calc-spar. A 
fel^^ of small quartz-pebbles, enclosed in a matrix of fine sandstone (mainly of 
spa ne materials), coloured dark red with peroxide of iron, is met with in two places 
e Ween Charters Towers and the Burdekin. In these stratified rocks no fossils have 
as yet been detected. 
Again, in the valley of the Reid, the Middle Devonian limestones rest unconform- 
f greywackes, &c., which are probably of the same age as the stratified rocks west 
arters Towers, and have interstratified with them some thick beds of brecciated 
volcanic ash. 
* Quart. Journ. Geol. Soo., vol. xxviii., p 384. 
+ Brisbane : by Authority : 1879 p. 15. 
