Page:Cyclopedia of Western Australia, volume 1.pdf/39
is a very persistent boulder bed, the component pebbles of which are covered with striæ of such a nature as to suggest that they owe their origin to ice action. Sections occur which show that this bed does not attain any great thickness, and that it is crowded with pebbles and boulders of granite, etc., embedded in a calcareous, fossiliferous matrix, which contains fragments of Spirifera, Productus, and Polyzoa, in addition to Aviculopecten tenuicollis. The fossil contents imply a marine origin for the boulder bed. It, therefore, can hardly be a glacial moraine, and it is more than likely that the materials were transported by floating ice, which deposited its burden on the sea floor. Wherever seen in situ it has been found that this glacial boulder bed (the Lyons Conglomerate) does not lie quite at the base of the Permo-Carboniferous rocks as developed in Western Australia. The Lyons Conglomerate marks an important geological horizon, which has been proved to extend for a distance of about 200 miles.
In the Irwin River district the Permo-Carboniferous rocks present an uninterrupted series of shales, clays, and sandstones, with occasional beds of limestone which are arranged in a very broad anticlinal fold, the axis of which trends generally north and south. About the middle of the series there occurs a zone of argillaceous limestones, containing a heterogeneous collection of striated boulders such as ice action alone can produce. The stratigraphical position of the boulder bed shows the horizon to be interbedded with marine strata, the equivalents of those in the Gascoyne.
The Collie River beds, which attain a thickness of at least 2,000 ft., are of considerable importance by reason of the fact that they contain coal seams to a total thickness of over 140 ft. The beds, which cover an area of about 500 square miles, consist of shales, sandstones, and grits. The boundary of the field is, with one local exception, everywhere defined by faults, one of which has been estimated to have a downthrow bo the north-east of at least 2,000 ft. The Collie River beds have yielded the following plants:—Glossopteris browniana; G. browniana, var. indica; G. browniana, var. communis; G. browniana, var. angustifolia; G. browniana gangamopteroides; and the following Foraminifera: Endothyra, Valvulina plicata, Bulimina Truncatulina haidinyeri, and Pulvinulina exigua.
The Permo-Carboniferous rocks of Western Australia have yielded a rich assemblage of fossils, among which are:—
- Rhizopoda. Nubecularia Stephensi, How.
- Anthozoa. Amplexus pustulosus, Hudl.; A. Selwyni, De Kon.; Cyathophyllum depressum, Hinde; C. virgatum, Hinde; Pleurophyllum Australe, Hinde; P. sulcatum, Hinde; Alveolites obscurus, De Kon.; Hexagonella (Evactinopora) crucialis, Hudl.; H. dendroidea, Hudl.; Syringopora reticulata, var. patula.
- Crinoidea. Actinocrinus, sp.; Platycrinus, sp.
- Tubicola. Spirorbis ambiguus, Flem.
- Bryozoa. Fenestella plebeia; F. fossula; Polypora Australis, Hinde; Protoretepora ampla, Lonsd.
- Brachiopoda. Aulosteges Baracoodensis, Eth. fils; Chonetes Pratti, Davidson; Derbyia cf. senilis, Phill.; Orthis cf. Michelini, Martin; Orthotetes (Streptorhynchus) senilis, Phill.; Productus brachythœrus, Sow.; P. cf. Cora, d'Orb; P. cf. margaritaceux, Phill.; P. scabriculus, Martin; P. semireticulatus, Martin; P. pugilis, Phill.; P. subquadratus, Morris; P. tenuistriatus, De Vern; P. Foordi, Eth. fils; P. undatus, Defr.; Strophalosia Clarkei, Eth. fils; Strophomena analoga, Phill.; Actinoconchus cf. planosulcatus, Phill.; Cleiothyris (Athyris) Macleayana, Eth. fils; C. var. Baracoodensis, Eth. fils; C. Roysii, Lev.; Cyrtina carbonaria, var. Australasica, Eth. fils; Dielasma (Terebratula) nobilis, Eth. fils; D. sacculus, Martin; D. Lastata, Sow.; D. amygdala, Dana; D. cymbalformis, Morris; Reticularia crebristria, Morris; R. lineata, Martin; Rhynchonella (Hypothyris) cuboides, Sow.; R. pleurodon, Phill.; R. pugnus, Martin; Seminula subtilita, Hall; Spirifera avicula, Sow.; S. convoluta; S. disjuncta, Sow.; S. glabra, Martin; S. Hardmani, Foord; S. Kimberleyensis, Foord; S. lata, McCoy; S. Musakheylensis, var. Australis, Foord; S. striata, Martin; S. Stutchburii, Eth. fils; S. trigonalis, Martin; S. vespertilio, Sow.; Syringothyris exsuperans, De Kon.
- Pelecypoda. Aviculopecten multiradiata, Eth. père; A. sprenti, Johns; A. tenuicollis, Cardiomorpha oblonga, Sow.; Deltopecten (Aviculopecten) Illawarensis, Morris; D. tenuisulcus, Dana; D. leinœformis, Morris; D. subquinquelineatus, McCoy; Myalina Mingenewensis, Eth. fils; Parallelodon (Palœarca) subarguta, De Kon.; Stutchburia cf. Randsi, Eth. fils; Pleurophorus (Pachydomus) carinatus, Morris.
- Gastropoda. Baylea (Ivania) Levellii, De Kon.; Bellerophon costatus, Sow.; B. decussatus, Flem.; Ptychomphalina Maitlandi, Eth. fils.
- Cephalopoda. Cœlonautilus Chesterensis, De Kon.; Discites cf. Omalianus, De Kon.; Gastrioceras Jacksoni, Eth. fils; G. sphœricum, Goldf.; Agathiceras micromphalum, Morris.
- Crustacea. Phillipsia grandis, Eth. fils.
- Pisces. Edestus Davisii, H. Wood.
Jurassic. The Jurassic rocks of the State have a fairly wide extent, especially in the Champion Bay district, near Geraldton. Rocks of this age have also been recorded from Shark Bay and also from Cape Riche to the east of Albany. From this latter locality Ammonites (Perisphinctes) Championensis, sp. nov., has been recorded, but there is some doubt as to whether or not this specimen has been correctly localized, or that it really came from Champion Bay. The Champion