BINNIE: MESOZOIC rocks of the north-east coast of IRELAND. 59 
collection profitable, it also contains siliceous nodules. The sand is 
sometimes quite red, sometimes yellow, and sometimes cliloritic. 
When green, the colour is due to the presence of glauconite. 
The Greensand is the most constant of the Mesozoic strata, 
having been found nearly everjrsvhere along the whole line of section. 
Everywhere, where the two can be compared, it seems to follow 
the dip of the Lias, It is sometimes hardened into a sandstone, con- 
sisting of the Glauconite and quartz gTaius imbedded in a cement of 
Calcium Carbonate, probably derived from the chalk. When indu- 
rated by an intrusive dyke there seems to be no chemical change, 
but merely a hardening. 
Mr. Tate considers the Hibernian Greensand to belong to the 
^tage cenomanien of D'Orbigny. The upper part of the formation is 
very intimately associated with the overlying chalk. Tate gives the 
following typical section at Woodburn river : — 
(ci) Glauconite Sands. These are dark gTeen, consisting of Glau- 
conite, with arenacious grains in a slightly argillaceous paste. 
This is the most persistent of the sub-divisions of the Upper 
Greensand. The fossil contents are chiefly confined to a bed 
characterised by the abundance of Exogyra conica, which bed 
occupies a median position in this sub-division, and forms a 
very good feature by means of which this sub-division may be 
traced. There are a few phosphate" nodules in the lower bed. 
This zone has yielded thirty-six species mostly obtained from 
Whitehead during the construction of the railway. A few of 
them are named in the following list : — 
Exogyra conica. Area carinata. 
Pecten orbicularis. Belemnites ultimus. 
Pecten quinquecostatus. Ditrupa deformis. 
(6) Grey marls, yellow sandstones and chert. These contain few 
species and are limited in thickness ; the heading gives their 
character. They are found at Woodburn River, Cave Hill, and 
Island Magee. Their characteristic fossils are : — 
Ostrea carinata. Vermicularia quinquecarinata. 
„ Dutempleii. 
Avicula lineata. 
Ammonites varians. 
Pecten virgatus. 
