676 EEFORT— 1886. 



In conclusion, Tate's admirable classification presents us with well-defined 

 types, generally recognisable almost at a glance by the practised eye, and bounded 

 by lines as good probably as from the complications of the structure (faults, 

 obscurities, &c.) could be expected. His names, if not high-sounding, are at 

 least sufficiently expressive. 



33 



g 

 o 



8. Tlie Culm Measures of Devonshire} By W. A. E. Usshee, F.G.S. 



The late Professor Phillips contributed the most considerable and important 

 part of the literature of this subject in ' The Palaeozoic Fossils of Somerset, Devon, 

 and Cornwall,' a work from which several quotations are given ; Mr. T. M. Hall 

 and other writers are cited as to the occurrence of anthracite in the neighbourhood 

 of Bideford, &c. 



After having observed the Culm Measures on the borders of the Triassic area 

 for some years, the author was enabled to study them in detail during the years 

 1876 and 1877, his researches being confined to the area east of a line between 

 Hartland Point and Okehampton. In this area he discovered that the Culm 

 Measures were broadly divisible into three groups, which, however, owing to the 

 passage of one group into another, to local intercalations, and to the innumerable 

 flexures and disturbances by which the main synclinal structure is obscured, 

 cannot be separated by hard and fast lines — at least, on the one-inch scale. 



The following is the general classification given : — 



/uDoer Effo-esford tvnel^^^^', ^^*^*^^ ^Y^^^' ^"^^^ bedded grey grits, and 

 ft^ • 6c 1 dark grey shales and slaty beds. 



{Thick-bedded, grey, greenish, and reddish sandy 

 grits, associated with marly splitting shales in 

 _, places ; irregular grits, slates, and shales. 



{Dark grey shales with grit-beds, generally thin and even, slaty 

 and splintery shales (St. David's, Exeter, type), even-bedded 

 cherty shales and grits (Coddon Hill type), limestones and 

 dark grey shales. 



Some leading characters in each group are then pointed out. The Lower 

 Culm Measures are assigned a breadth of from two to three miles on their northern 

 outcrop, and of about fifteen miles in the southern area on each side of Dartmoor. 

 The impersistent character of the limestones of this series, and the frequent 

 absence of their most marked characters from the beds on the (Joddon Hill 

 horizon, is also mentioned. The apparent passage of the Cukn Measures into 

 Devonian in the north is contrasted with the seeming unconformity between these 

 strata in the south. 



The Middle Culm Measures attain a breadth of about four miles in their 

 northern, and from four to five in their southern outcrop. Some structural pecu- 

 liarities in this series, and a part of the coast section between Portledge Mouth 

 and Westward Ho, are briefly described. 



Tlie Upper Culm Measures are said to form a band of from six to seven miles 

 in wirlth. The even character of the bedding and the iuterstratificatious of dark 

 grey shales render the contortions of this series on the coast between Portledge 

 Mouth and CloveUy very apparent. 



9. Denudation and Deposition by tlie Agency of Waves experimentally 

 considered. — By A. R. Hunt, F.0.8. 



The author, after referring to the importance of waves as agents of denudation, 

 said that endless cases might be cited in proof of the conflict of authority as to 

 the depth at which wave-action practically afiected the sea-bottom. Until this 



' Printed in full in the Geol. Mag. Dec. 3, vol. iv. p. 10, 1887. 



