part 2] GEOLOoi* of the meldon valleys. 7£> 



lie counter to the dip. These planes have been more or less, 

 successfully invaded by at least three successive series of igneous 

 rocks, the order of which, commencing with the earliest, is as 

 follows : — 



(a) A felsite with phenocrysts of micropegmatite. 



(b) A series, hereafter called the ' Dark Igneous.' 



(c) Granitoid veins, subdivided into 



(1) The Meldon aplite and its associates. 



(2) Fine-grained granites of the ordinary Dartmoor type. 



The evidence on which this chronology has been based seems 

 fairly clear. The felsite with micropegmatite phenocrysts occurs 

 as inclusions in the ' dark igneous ' rocks. The ' dark igneous ' 

 rocks occur as inclusions in the Meldon aplite. The Meldon 

 aplite occurs as veins in the ' dark igneous ' rocks. No evidence is 

 available as to the relative age of the Meldon aplite and the 



granite-veins. 



III. Tile Shales. 



The shales fall clearly into two divisions, the calcareous and the- 

 aluminous. These meet without any apparent transition-beds, 

 but without unconformity, on a well-defined boundary, which may 

 be approximately taken as passing immediately south of LXXYI, 

 S.E. 27, on the Eedaven ; a little north of LXXVI, S.E. 8, by the 

 Flushcombe brook; and between LXXVI, S.E. 9, and LXXVI, 

 S.W. 7, probably rather nearer the latter. 



South of this line all the shales are aluminous, and north 

 of it all the shales are calcareous, until the London & South- 

 Western liailway quarry is reached, where an aluminous rock 

 comes in abruptly and again without apparent unconformity. 



The limestone has place as one of the upper members of the 

 calcareous series, if the apparent succession is the real succession, 

 which there seems no reason to doubt. 



The Earlier Aluminous Hocks. 



Most of the rocks lying above the granite and below the cal- 

 careous series are in reality iine-grained impure grits. They lie 

 well within the metamorphic aureole surrounding the granite, and 

 have been subjected not only to the consequent general alteration, 

 but locally to more intense action where the granite- and aplite- 

 veins penetrate them. 



Hard by and for some little distance from the granite the shales 

 are red-brown and rather soft. Specimens from LXXVI, S.E. 34, 

 near Moor Brook, may be taken as a type. The rock varies somewhat 

 macroscopic-ally, and of the two sections described [31 «, 34 b] the 

 former is grey-brown, without any tint of red. All specimens 

 look gritty, and are minutely banded. 



No. 34 a contains much very pale mica in scales with occasional 

 larger forms, there are small cinnamon-brown tourmalines scattered 

 through the slide, and rutile in grains and minute well-formed 



