ROCKS OF SOUTH DEVON. 515 



The following may be mentioned : — 



Stromatopora ffupschii, Barg., from Langs Copse, Compton 



near Marldon, Buckley Wood. 

 Datiia, sp., South of Colway Cross, west of Bishopsteignton. 

 Actinostroma hehhornense,W\Q\\.^ Coorabes End Quarry, south of 



Whiteway Farm, Daddyhole Knoll, Yarneford Copse 



Quarry. 

 Actinostroma clathratum, IS'ich., Broadridge Wood. 

 Actinostroma verrucosum, Goldf., Old Quarry, Coombes End. 

 Stromatopo7'a bucJialiensis, Barg., 8tantor. 

 Clathrodictjfum, Highlands, Totnes. 



§ VIII. Conclusions. 



From the above observations it will be seen that by detailed 

 investigations, aided by the discovery of characteristic fossils, the 

 Devonian rocks of this part of South Devon fall naturally into 

 Upper, Middle, and Lower groups, each possessing distinctive litho- 

 logical and palseontological characteristics, yet also exhibiting in 

 both respects points of similarit}* which prevent the definition of 

 sharp boundary-lines. 



The structure of the country, owing to faulting and plication, and 

 to a still greater degree owing to the impersistence of the limestones, 

 either from the abrupt termination of organic growth, from, gradual 

 or irregular replacement by slate, or from episodes of vulcanicity 

 during their accumulation, is only to be interpreted by piecing the 

 evidence and amalgamating disconnected data to form a connected 

 sequence. 



Although there is no evidence of atolls, and barrier and fringing 

 reefs are out of the question, in a district where volcanic materials 

 were being spread beneath the sea during a period in which coral- 

 line growth was taking place, and the debris of organic existence 

 actually strewed the sea-bottom upon which the earliest volcanic 

 ejectamenta were outpoured, it cannot be denied that we have con- 

 ditions manifested somewhat similar to those which are known to 

 be favourable to coralline growth in the present day in the Java 

 seas. 



The discovery of Goniatites near Whiteway Farm in beds which 

 directly overlie massive limestones of the Chudleigh type, them- 

 selves succeeded by bedded limestones containing Strimjocephalus 

 and Heliolites poroses, which are separated b}^ inverted aphanites 

 and schalsteins from slates with both Middle- and Lower-Devonian 

 affinities, affords, notwithstanding inverted dips, at once the most 

 important and the most connected succession to be met with in 

 the district. 



It will be seen that the irregular unfaulted junctions between 

 the Upper-Devonian slates and the limestones in some places give 

 colour to the supposition that the limestones were partly accumu- 

 lated as coral-banks, and that the muddy sedimentation on their 

 margin may have taken place at a much slower rate. 



