A. Champernoicne — Age of the Ashburfon Limestone. 413 



paces takes us to the furthest limestone face, which, distance at 50*^ 

 gives a thickness of more than 300 feet (354, if yards were paced, 

 and I cannot estimate it at much less). Between this and the 

 turnpike road, along the level ground, we must presume the axis of 

 syncline passes. The Eew Mill fault, dying out at this point as 

 shown by De la Beche, probably exercises little or no eifect on the 

 limestone dijDS. 



There are other interesting facts connected with, these limestones, 

 but none more so than the apparent gaps in its continuity. For 

 instance, after the first railway cutting South of Ashburton station 

 there is no limestone until we reach the Pridhamsleigh fault : it is 

 abruptly lost for f of a mile. This is caused by an East and West 

 fault passing Chewley and Summer Hill, and meeting the Pridhams- 

 leigh fault at an angle of about 40°. These two heave the wedge 

 of country between them and " throw out " the limestone fold. The 

 evidence is clear; for the mass of igneous rock constituting Pear 

 Tree hill is shifted towards the East and laid open in the railway 

 cutting (9th milepost from Totnes) dipping about 35° towards E. 

 25° S., the intervening ground towards the station being low and 

 swampy where the fault passes.^ The rocks immediately S.E. of the 

 town appear identical with those on the N.W., the limestone being 

 troughed in them. 



A similar gap occurs immediately S.W. of Buckfastleigh, between 

 that place and the Dean limestone ; but, interesting as the structure 

 is, present space will not admit of an attempt to describe it, more 

 than to say that the Dean band is evidently thrown down by a fault 

 on the north, which is metalliferous, having been once worked as an 

 iron mine. 



In the country to the East and South-East of the whole belt, 

 taking Woodland as a centre between the Dart and the Lemon, the 

 igneous rocks, ash-beds and lavas, rather than the "greenstones," 

 will help to unravel whatever may be obscure in the structure ; my 

 maps already begin to foreshadow the appearance, but we must 

 remember that, igneous rocks excepted, we have to deal with an 

 almost purely argillaceoias series, and that there is little at first 

 sight to dispel the illusion of an ascending series from the Ashburton 

 to the Ipplepen, etc., limestones. 



It is necessary however to point out that, at a certain distance from 

 the South-east of the limestone band, there runs a belt of coloured 

 slates, purple and greenish, which have an important bearing on the 

 structure. They appear about a mile East of Buckfastleigh, very 

 narrow at first, but beyond the Pridhamsleigh fault, in the upcast 

 country about Penrecca slate quarry, are more striking ; they can be 

 traced continuously towards the North-east, only afi"ected by N.W. 

 and S.E. faults which equally shift all the rocks, and they curve 

 round with the strike near Knighton and by Knowle Hill, reappear- 

 ing on the opposite side of the Teign, where they are exposed in the 

 railway cutting near Combe cellars. 



Intrusive rocks, individually of small extent, break out along their 

 ^ This shifted continuation of the Pear Tree rock is omitted on the map. 



