‘ParrL§1j] «ARCH AN, ae ee 
of those in true foraminiferal structures. Other observers, notably 
Professors King and Rowney of Galway and Mobius of Kiel, have 
opposed the organic nature of Hozoon, and have endeavoured to 
show that the supposed canals and passages are merely infiltration 
velnings of serpentine in the calcite. In some cases, however, the 
- “canal-system ” is not filled with serpentine but with dolomite, which 
seems to prove that the cavities must have existed before either 
dolomite or serpentine was introduced into the substance. Dr. 
Carpenter contends that the disposition of these passages in his 
decalcified specimens is very regular, and quite unlike any mineral 
infiltration with which he is acquainted. In the Archean rocks of 
Bohemia and Bavaria specimens were some years ago obtained 
showing a structure like that of the Canadian Kozoon. They were 
accordingly described as of organic origin, under the respective 
names of Hozoon Bohemicum and H. Bavaricum. But their true 
-imineral nature appears to be now generally admitted. 
The opinion of the organic nature of Hozoon has been supposed 
to receive support from the large quantity of graphite found 
throughout the Archean rocks of Canada and the northern parts*of 
the United States. This mineral occurs partly in veins, but chiefly 
disseminated in scales and lamine in the limestones and as in- 
dependent layers. Dr. Dawson estimates the aggregate amount of it 
in one band of limestone in the Ottawa district as not less than from 
20 to 30 feet, and he thinks it is hardly an exaggeration to say that 
there is as much carbon in the Laurentian as in equivalent areas of 
the Carboniferous system. He compares some of the pure bands of 
eraphite to beds of coal, and maintains that no other source for their 
origin can be imagined than the decomposition of carbon dioxide by 
living plants. In the largest of three beds of graphite at St. John 
he has found what he considers may be fibrous structure indicative 
of the existence of land-plants. | 
Still further’ evidence in favour of organized existence during 
Archeean time in the North American area has been adduced from 
the remarkably thick and abundant masses of iron-ore associated 
with the Laurentian rocks of Canada and the United States. Dr. 
Sterry Hunt has called attention to these ores as proving the 
precipitation of iron by decomposing vegetation during the Lauren- 
tian period on a more gigantic scale than at any subsequent 
geological epoch. Some of the beds of magnetic iron range up to 
200 feet in thickness. Large masses also of hematite and -titanife- 
rous iron, as well as of iron sulphides, occur in the Canadian Archean 
series. 
Besides the granitic and other veins and bands which are so 
intimately associated especially with the older and more crystalline 
portions of the Archean rocks, there have been noticed, in the 
younger portions, more or less satisfactory traces of contemporaneous 
volcanic action. In the iron regions of Lake Superior beds of 
1 “ Geology of Canada,” 1863, p. 573. 
