CAMBRIAN 235 



be considered Cambrian. In this case it is not unreasonable to class the older 

 series as Pre-Cambrian. 



CAMBRIAN 



Rocks provisionally referred by us to this horizon are rejjresented in the form 

 of a limestone breccia at the foot of the great granite cliffs at Lower Glacier Depot 

 on the north-west side of the entrance to the Beardmore Glacier, about 8 miles 

 southerly from Mount Hope. The specimen of this breccia, in which what we 

 considered to be Cambrian fossils were obtained, was collected by Wild of the 

 Southern Party of the Shackleton Expedition. This rock has been described 

 in detail by Professor E. W. Skeats, D.Sc, in Part II. of this work. Professor 

 Skeats states that about forty sections and eight hand-specimens of limestone were 

 submitted to him for description, possibly all of Cambrian age. The rock referred to 

 from Lower Glacier Depot is described as strictly a dolomitic breccia ; the breccia 

 is dark grey in colour, the fragments contained in it being darker than the cementing 

 material, which is calcareous. Professor Skeats considers that the rock was com- 

 pletely dolomitised before it was broken up. He mentions that intermixed with the 

 dominant dolomite are occasional small fragments of calcareous and micaceous sand- 

 stone, chert, dark cherty shale or silicified oolitic limestone. Angular fragments 

 of quartz are sometimes abundant. The breccia occurred in very large blocks, and 

 form apparently part of the left lateral moraine of the Beardmore Glacier. The 

 great interest which attaches to this breccia is that it contains two dominant types of 

 fossils, of which one has been determined by Mr. T. Griffith Taylor as being referable 

 to the Archwocyathince. Remains of the sponge spicules, and what appeared to 

 be fragments of crusts of trilobites, may also be recognised. Mr. Taylor confidently 

 asserts that the bulk of the calcareous organisms are fragments of the Arch(BOcya- 

 thinoe. As the individual fragments in the breccia are small, as a rule not 

 exceeding one-third of an inch in diameter, it is only the embryonic forms of the 

 Archwocyathince that are at all complete. Mr. Taylor believes that he can identify 

 the following : — 



Archceocyathus akin to A. profundus. 



A hand specimen of Protopharetra, akin to P. radiata (Bornemann), P. rete 

 (Taylor), P. duhiosa. 



The following is Mr. Taylor's detailed description, with figures : — 



Introduction* Amongst the specimens collected on the Beardmore Glacier by Sir 

 Ernest Shackleton's Expedition was a piece of yellowish limestone breccia. This was 

 cut into sections at the University of Sydney, and was found to contain numerous 

 microscopic fossils, which it was suspected were allied to the Archceocyathinas. 



I was able to confirm this, and the sections, numbering about twenty, were 



* By Griffith Taylor, B.Sc, B.E.,'B.A., F.G.S., Senior Geologist, Brit. Ant. Exped., 1910-1913. 



