164 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. (Dec. 22, 
value of this ore. The poorer kind, as lithomarge, may be used as a 
flux, while the richer bole and pisolite are made to yield a superior 
iron, suitable alike for steel- or machinery-purposes*. 
The growing demand for this Antrim ore proves its utility; during 
the past year upwards of 50,000 tons were shipped to England from 
several ports along the Antrim coast. The mining has become a 
steady and increasing industry in the county. 
VI. Grnerat Conciustions. 
1. That during the period of volcanic activity in the N.E. of Ire- 
land, there was a cessation of igneous eruption over certain areas, 
during which lacustrine deposits were formed, and a growth of ter- 
restrial plants took place. 
As to the extent of the lake, or of the land-surface, the data are 
incomplete to form any conclusions. The lignite in the Giant’s- 
Causeway basalt, the leaf-beds of the Isle of Mull, and the bituminous 
deposits in other localities may be on the same horizon. However, 
it is perhaps more probable that these several land-accumulations 
may have been formed in isolated areas, though during the one 
period of rest in the volcanic forces. 
2. The preceding remarks imply that there were at least two 
periods of volcanic activity, the plant-beds or lignite marking an 
unconformability of an upper basaltic series to alower. The plants 
being of Upper-Miocene age enables us to assign a position in the 
scale of geological time to the superior basalts. What may be the 
age of the inferior series, is a question that can only be approxi- 
mately answered. That itis newer than the White Limestone (Upper 
Chalk) and older than the upper Miocene, is apparent. 
3. The older basaltic series has undergone metamorphic changes 
in the composition of some of its interstratified lavas. The boles 
and ochres, which are decomposed basalts, are probably con- 
nected with subaqueous igneous flows, whilst the pisolitic iron-ore 
band, which is a metamorphosed bole, indicates subaerial action, and 
that during the period of emergence the bole was subjected to further 
metamorphism by heated superimposed basalt. 
Discussion. 
Mr. D. Forzus was not prepared to admit some of the theoretical 
conclusions of the authors, and objected to calling in metamorphism 
to account for all that was hard to be understood. He could not 
recognize the division of beds so similar in character into two classes. 
He wished to know, assuming that the iron-ore merely resulted 
from the decomposition of the basalt, what became of all the silica 
and alumina which constituted three-fourths of the mass. The 
origin of the -pisolitic ores was in fact organic. In Sweden certain 
lakes were regularly dredged each year for the pisolitic ore still in 
* It would be of great importance to the prosperity of the north of Ireland if 
the ore could be smelted at home. Furnaces might easily be erected near the 
mines for the reduction of the richer pisolite; limestone is abundant ; and coal 
can be procured easily and cheaply from Scotland. 
