120 REPORTS ON THE STATE OF SCIENCE. — 1915. 



h,. Red, sandy and micaceous Limestone in nodules ; trilobite frag- ft. in. 



ments very plentiful 10 



a. Ijower Comley Sandstone. 



a,. Mottled red and green micaceous sandstone, soft and somewhat 



fissile above, harder and more compact below 4 



a.,. Green micaceous sandstone with rusty spots, and one specimen of 



Hyolithellus 6 



a,. Green micaceous sandstone ; base not seen 60 



Western End of the Section. 



The dip of the beds throughout is 80°, N.75° E. 



This section is now filled in. It repeats in all its main features tie 

 sequence shown in the Quarry Ridge ■* of Comley, which is aboxit one 

 and a half miles away. It is noteworthy that the dividing line between 

 the Taconian and Paradoxidian (=the plane of erosion) lies at exactly 

 the same horizon (the top of the Black Limestone) in the two places, 

 though at Robin's Tump, which is about half-way between them, the 

 Taconian strata are seen to have been eroded to a much lower level.* 

 In a few particulars the section now being dealt with supplements the 

 information given by Excavations Nos. 1 and 2. 



(i) The Conglomerate (r-) has here a distinctly sandy bed at the top [c^] 

 and another at the base {c.2), indicating that it is complete and not affected 

 by the strike faulting, so prevalent in the Quarry Ridge of Comley. 



(ii) This Conglomerate contains many angular blocks of Black Lime- 

 stone of both the granular and the compact varieties (beds h^ and h^ of 

 the section) which had not been noted from the Conglomerate at Comley. 

 There are also, as at Comley, numerous blocks of the Grey and Olenellus 

 Limestones. It is now clear that all the Limestone bands were subject 

 to erosion at the time when the Conglomerate was formed. 



(iii) The black skin (c, ) at the base of the Conglomerate has its counter- 

 part at Comley in a similar black deposit, which contains Paradoxides, 

 Dorypyge, and a species referred to Acroihyra. The same species of 

 Acrothyra is found in the sandy bed c^, but the Trilobites in that bed 

 have not been identified. 



(iv) In the Cwms section the compact or lower portion (64) of the 

 Black Limestone is crowded with fragments of Trilobites, many of which 

 have the reticulate surface characters of Olenellus or some other genus 

 of the Mesonacidse. This necessitated a further study of Excavation 

 No. 2 at Comley (see following page). 



Excavation No. 55, — The Cwms Brooh. 



The Lower and Middle Cambrian rocks are naturally exposed in the 

 bed of this stream for about 300 yards to the southward. The section 

 across the junction was opened out and the contact was proved to be 

 a faulted one, the whole of the Limestones of the lower series being cut 

 out at this point. 



Excavation No. 56. — The Lower Ridge in the Cwms. 



A few small trials were made where the Qaartzite composing the ridge 

 outcrops, but no continuous section could be observed, without undue 

 disturbance of the cultivated ground. The presence of greenish-grey 

 and mottled sandstone lying above the quartzite was noted. 



' O-p. jam cit. 



• Bep. Brit. Assoc. 1911, Portsmouth, 1912, pp. 112, 113, and figs. 1, 2, and 3, 



