GEOLOGY 



her of species, though most of them are badly preserved. They include 

 several corals, polyozoa, crinoids, brachiopods, with more rarely Actinoceras, 

 Orthoceras and trilobites. Mr. C. W. Peach records remains of the 

 Devonian trilobite, Phacops latifrons. 



North of St. Columb Forth we have a range of a| miles of 

 brightly variegated slates, purple, green, buff and grey, similar to those 

 between Fowey and Polperro, the Devonshire counterparts of which 

 have been named by Mr. Ussher the ' Dartmouth and King's Wear Slate 

 Group.' These rocks contain fish-remains. In Watergate Bay the 

 fossiliferous beds are thin and not plentiful. In some beds the fossil 

 scales, spines and plates are abundant, in others more scattered. Pteraspis 

 cornubica is one of the most frequent forms and may be reckoned a 

 Lower Devonian fossil. There are occasional fossiliferous beds in Step 

 Cove, the northern boundary of Watergate Bay, in Beacon Cove and 

 Mawgan Forth, but it is not till we reach Bedruthan Steps that we are 

 rewarded with any determinable zonal fossil. Bedruthan is a most 

 interesting locality. Huge blocks are constantly falling from the high 

 cliffs, and some of them come from fossiliferous beds inaccessible to 

 the climber. The coast is open to the Atlantic seas, and these lift the 

 sand and dash it on the rocks, creating such a scour that fresh fossils are 

 weathered out constantly, and the fossil seeker may find a rich treasure 

 when he least expects it. The rocks in situ on the foreshore are in cer- 

 tain places crowded with organic remains, a few of which may show 

 good structure and some others may be in a fair state of preservation, 

 though the great majority are indeterminable. The most abundant are 

 corals, crinoids, polyzoa, brachiopods, gastropods, Orthoceras, fish remains, 

 with an occasional trilobite and starfish, etc. To this list fragments of a 

 new fossil have lately been found in abundance, which may be looked on 

 as a zonal fossil, 1 Pteroconus mirus, Hinde (Nereitopsis, Upfield Green). 

 The most perfect specimen is in the British Museum. 



Both Samaritan Island and Diggory Island yield fossils, the latter 

 some good examples of Pleurodictyum ; and ascending Pentire Steps at the 

 north end of the Bedruthan range we pass the bold igneous peninsula 

 of Park Head, and if we descend into Lower Butter Cove may find a 

 Petraia, Conularia, or fragment of Pteroconus, and for certain some crinoidal 

 fragments. There are several distinct fossiliferous horizons at Porth Mear. 

 Trescore Islands and mainland, and Boathouse Cove adjoining, show many 

 fossils, some of which are interesting ; amongst others Phacops latifrons (?) 

 has been found. Porth Cothan exposes a great surface of blue slate with 

 occasional corals, trilobites and Conularia. 



Pleurodictyum occurs in Rowan Cove north of Porth Cothan, and 

 northward of that we have found no fossil of value until we reach Con- 

 stantine Bay and its northern division Booby's Bay, immediately south of 

 Trevose Head. Here an Upper Devonian fossil, Cardiola retrostriata, is 

 found with Bactrites, Zaphrentis, Pachypora, Phacops, a brachiopod, Pleuro- 

 dictyum, Tentaculites, etc. The fossil however which characterizes the 



1 Geol. Mag. decade iv. vol. vii. No. 430, 1900 ; Trans. R. Geol. Soc. Corn. vol. xii. pt. 5, 1900. 



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