Vol. 70.] OF THE COUNTRY AROUND HUWTLT. 269 



III. The Nox-Foliated Igxeous Rocks. 

 (1) General Characteristics. 



The period of great foliation did not, however, terminate the 

 igneous activity of the region, as is proved by the presence of the 

 non-foliated (acid and basic) intrusive rocks which form the subject 

 of this paper. They lie in the concavity formed by the changing 

 strike of the foliation. Other non-foliated igneous rocks include 

 muscovite-granite and pegmatites, lying (outside the area now 

 under consideration) south and west of the Hill of Milleath 

 among foliated rocks. To the action of these, or more probably of 

 the serpentine, may be due the beautiful garnet-chlorite-schists of 

 this area. Near the farm of Bogmoon, also, a non-foliated felspar- 

 porplmy occurs in an area of foliated rocks. 



(a) The norite group. — In this area there are three non- 

 foliated intrusions and a laro;e number of associated dvkes. The 

 largest and earliest of these intrusions — a norite — extends from 

 Fourman Hill to Battlehill. Passing out of sight beneath the 

 alluvium about Huntly, it reappears with slight modifications in 

 Bin Quarry. 



This type presents variations, both in texture and in composition. 

 The normal intrusion is a norite with ophitic texture ; but in 

 Kinnoir Park it is a gabbro with granitic texture, and on the 

 slopes of Mungo a finely-granular norite. A troctolite is also met 

 with on the western slopes of Mungo. 



On the west the norite appears to pass into olivine-gabbros, trocto- 

 lites, and picrites. No line can be laid down separating these 

 types one from the other, or separating the series, as a whole, from 

 the norite. The western limit of the intrusions is sharply defined 

 by an outcrop of hornfelsed mica-schists near Cairnford Bridge, 

 west of the Deveron. A garnetiferous modification of the magma 

 occurs, apparently in situ, near Drumdelgie ; but the boundary 

 north of this point is conjectural, until the northern edge of Bin 

 Wood is entered. Here a series of contact-rocks is found lying 

 on the south side of the Cairnie Burn. The} 7- can be followed for 

 some distance, but are finally lost in the low-lying ground termed 

 in the Ordnance Survey map Mortlach Loch. 



Of the various types in the western portion of the area, the more 

 basic members occur farthest west. Thus the picrite is best deve- 

 loped close to the margin, and occurs at the following localities : — 

 Queels, Cairnford Bridge, quarry east of Broadland, Pyotbush, 

 quarry near Lower Sinsharnie. In the last-named occurrence, the 

 rock is closely related to the troctolite type. 1 An essentially- 

 similar rock forms the main portion of the rail way- cutting at 

 Bothiemay, showing the quaquaversal dip of the flat joints. 



1 As used throughout this paper, the term picrite denotes an olivine- 

 pyroxene-rock containing an appreciable amount of bytownvte. 



