i8 The American Geologist. J"i>'' i^*^*- 
and their number, indicate .that the workable parts of the 
domes themselves occupy but a small proportion of the thick- 
ness of the Goldcnville. It is probable that the slate composes 
3% or less of the total thickness exposed in the formation. 
A source of slight error arises in neglecting the slate beds 
and partings which lie in the thick whin belts between the an- 
ticlines ; but observations indicate that this would not increase 
the total by more than .5%. Another source of uncertainty 
is the discontinuity of the strata. Between Moose River and 
the contact with the Halifax formation on the north, there is 
probably less than i% of slate, in a thickness of over 16,000 
feet. If we could get similar sections at some other place, on 
one dip, there might be found several times that amount. 
Vertical distribution of slate horizons. — Ixloreover, these 
slate horizons have a very erratic distribution in vertical suc- 
cession. Instead of a rhythmic alternation of whin and slate, 
there appear to be great depths of quartzyte almost barren of 
slate, between horizons which have a considerable proportion 
of slate to whin . And the thickness of these whin belts varies 
in different examples, ranging from somewhat less than a 
thousand to many thousand feet. It is impossible to give 
any average interval between the slate-bearing horizons, be- 
cause a study of the field shows no probability that these ho- 
rizons are of sufficient lateral extent to run under and over one 
another to a degree that would give a vertical arrangement in 
tiers. 
Continuity of strata: on the dip. — The question of the 
continuity of individual strata or groups of strata is a puzzling 
one. The absence of any distinctive horizons within the 
group, except the formation contact plane, makes exact state- 
ments impossible. But the slate horizons exposed by denuda- 
tion of the domes ofl'er a partial substitute. At about the 
longitude of Moose River there are five anticlines, from the 
ocean on the south to the Carboniferous lowland on the north, 
and excepting the Moose River and Caribou folds These 
are, from north to south, the Gold Lake-Goldenville, ]\Ioose- 
land-Gegogan, Lake Catcha-Salmon River. Tangier-Harrigan 
Cove, and Southern anticlines (z-id . Geol. Surv. Can., docs. 
611, 624, 634; N. S. sheets 49, 50, 51). Within a few min- 
utes of lons^itude east and west the mining districts of Gold 
