')() BTNNIE: MESOZOTC ROOKS OF THE NORTH-EAST COAST OF IRELAND. 
touch, sometimes hardened by intrusive dykes. The colouring matter 
is no doubt iron in the form of sesquioxide in the first case. These 
beds contain some bands of common salt, which is mined near 
Carrickfergus. The line of demarcation between the red and green 
colour is very sharp, the same hand specimens being parti-coloured. 
It is sometimes very difficult to distinguish the bluish-green marls from 
the Lias clay. The Trias is very nearly constant throughout the 
entire length of the section, being often of considerable thickness. 
The Rhretic or Avicula contorta" shales underlie the Lias, and 
are, generally speaking, tlie last to die out. Sections have been 
examined for a distance of twenty-four miles, from Lisburn to White- 
head. The bed is sometimes only one or two inches thick, but in Colin 
Glen it is nineteen feet, and at Waterloo fifty feet, its maximum 
development. The shales are often ver}^ much hardened, and some- 
times contain bands of argillaceous limestone. Portlock long ago 
drew attention to the fact that there were certain strata linking the 
Liassic and Triassic formations. 
Tate gives the following section of the occurrence of these beds 
in Cave Hill, near Belfast : — 
Dyke. 
1. Upper GreenBand. 
2. Marly Shales, 8 ft. 10 ins. 
Micaceous Sandstone, 2 ins. 
4. Shales with " Cardiura Rh?eticum," 1 ft. 
5. Indurated Shales, 1 ft. 3 in. 
The following fossils serve to indicate the age of these beds : — 
Aximis cloacinus. Pacunopsis. 
Cardium rhreticum, Pecten valoneusis, 
