24 A NEW FLOKA OF 



Megaceros Ifihi'rniom, Cervus Alces, Cervus ehpJms, the wild boar, 

 and remains of a horse. 



IGNEOUS ROCKS. 



There are two groups of igneous rocks in this district, of 

 different age and mineral composition — the felspathic and the 

 augitic ; or the porphyries and the basalts ; the former being of 

 a much greater age than the latter. 



1. Porphyry. — The Cheviots, a range of hills protruding 

 through, and rising high above, the stratified rocks in the north- 

 ern part of Northumberland, and extending into Roxburghshire, 

 are composed of porphyry, which, however, varies in its cha- 

 racter. Usually, the rock is a porphyrite, with a red felspathic 

 base, in which are scattered crystals of felspar. In some parts 

 it is a dark coloured dolerite, composed of labradorite and augite ; 

 and near to Yetholm it is a pitchstone porphyry. Not unfre- 

 quently it passes into a syenite, a crystalline compound of felspar, 

 hornblende, and mica ; and in some few cases it becomes a granite, 

 formed of felspar, quartz, mica, and a little hornblende. On the 

 north side of the Cheviot, in the Diamond Burn, there are masses 

 of quartz rock in which appear crystals of quartz, some white or 

 translucent, and a few others brown or amethystine. On the 

 Ridlees Burn, where stratified rocks abut against it, the por- 

 phyry is amygdaloidal, with geodes, in which are developed fine 

 quartz crystals, or which are filled with agates and calcedonies. 

 The great mass, however, is felspathic. 



The boundary line of this porphyritic range begins on the 

 borders, at Presson, and goes eastward to Brankston, where the 

 battle of riodden was fought ; it then bends southward to Yea- 

 vering, and by a series of undulations passes by Akeld, Wooler, 

 Ilderton and Brandon, to Ryle, whence it bends westward to 

 Prendwick, and thence, in a south-west direction, crosses the 

 Coquet, above Linn Brig, to Eidlee Hill ; after which it bends 

 to the north-west, and crossing the Coquet again, above Philip, 

 extends into Roxburghshire. Another part of the range is pro- 

 longed from Roxburghshire into the north side of the Reed above 



