ient soil
of good quality for agricultural purposes. They are, however,
largely intersected by mineral veins, containing silver, gold,
and other metals, and they will ultimately doubtless yield a rich
harvest to the miner. The Huronian Rocks have been identified,
with greater or less certainty, in other parts of North America,
and also in the Old World.

The total thickness of the Huronian Rocks in Canada is estimated
as being not less than 18,000 feet, but there is considerable
doubt as to their precise geological position. In their typical
area they rest unconformably on the edges of strata of _Lower_
Laurentian age; but they have never been seen in direct contact
with the _Upper_ Laurentian, and their exact relations to this
series are therefore doubtful. It is thus open to question whether
the Huronian Rocks constitute a distinct formation, to be
intercalated in point of time between the Laurentian and the
Cambrian groups; or whether, rather, they should not be considered
as the metamorphosed representatives of the Lower Cambrian Rocks
of other regions.

As regards the fossils of the Huronian Rocks, little can be said.
Some of the specimens of _Eozooen Canadense_ which have been
discovered in Canada are thought to come from rocks which are
probably of Huronian age. In Bavaria, Dr Guembel has described a
species of _Eozooen_ under the name of _Eozooen Bavaricum_, from
certain metamorphic limestones which he refers to the Huronian
formation. Lastly, the late Mr Billings described, from rocks
in Newfoundland apparently referable to the Huronian, certain
problematical limpet-shaped fossils, to which he gave the name
of _Aspidella_.

LITERATURE.

Amongst the works and memoirs which the student may consult with
regard to the Laurentian and Huronian deposits may be mentioned
the following:[10]--

(1) 'Report of Progress of the Geological Survey of Canada from its
Commencement to 1863,' pp. 38-49, and pp. 50-66.
(2) 'Manual of Geology.' Dana. 2d Ed. 1875.
(3) 'The Dawn of Life.' J. W, Dawson. 1876.
(4) "On the Occurrence of Organic Remains in the Laurentian Rocks
of Canada." Sir W. E. Logan. 'Quart. Journ. Geol. Soc.,'
xxi. 45-50.'
(5) "On the Structure of Certain Organic Remains in the Laurentian
Limestones of Canada." J. W. Dawson. 'Quart. Journ. Geol.
Soc.,' xxi. 51-59.
(6) "Additional Note on the Structure and Affinities of Eozooen
Canadense." W. B, Carpenter. 'Quart. Journ. Geol. S