24 TACONIC SYSTEM. 



Canada, in the Report of Progress for the year 1847, described the rocks on the 

 north side of Lake Huron, and constituting many of the adjacent islands, under the 

 name of "quartz rocks and sandstones, conglomerates, slates, and limestones," and 

 correctly identified them as resting unconformably upon the older granite and 

 syenitic gneiss, and succeeded unconformably by the Potsdam, but he did not call 

 them by any geological name. If he had read Emmons's " Taconic System," it is 

 difficult to conceive why he should have hesitated in referring the rocks to that System. 

 In the Report of Progress of 1856, he redescribed the rocks, under the name of the 

 " Huronian Series," which was adopted by the officers of the Canadian Survey, 

 without once mentioning the Taconic System. From that time forward authors 

 have generally used the name Huronian, and have almost annihilated the name 

 Taconic. The word Taconic, however, has priority over Huronian. It is equally 

 appropriate, and the definition of the fossils in the Upper Slates at once furnished 

 the means of traciDg it and determining it at different and distant places. The 

 word "Huronian" is, therefore, a synonym for Taconic, and comprehended, as used 

 originally by the Canadian Geologists, substantially the same series of rocks, though 

 not ascending quite so high. 



§ 43. A section of the so-called Huronian, but more properly called the Lower 

 Taconic, between Missisquoi and St. Mary's Rivers, in ascending order, is as follows : 



1. Gray quartzite, 500 feet. 



2. Greenish, red-weathering chloritic and epidotic slates, 2,000 " 



3. White quartzite, etc., 1,000 " 



4. Slate conglomerate, 1,280 " 



5. Limestone, ...••• 300 " 



6. Slate conglomerate, etc., 3,000 " 



7. Red quartzite, etc 2,300 " 



8. Red jasper conglomerates, etc., 2,150 " 



9. White quartzite, etc., 2,970 " 



10. Yellowish chert, etc. 400 " 



11. White quartzite, etc 1,500 " 



12. Yellowish chert, etc 200 " 



13. White quartzite 400 " 



Total, 18,000 " 



Another section adds to this one 4,000 feet, and even then the maximum thick- 

 ness of the series in that locality has not been reached. 



§ 44. Throughout the Huronian region, the whole series bears evidence of great 

 disturbance, and is frequently cut with intrusive masses of greenstone, granite, or 

 other igneous rocks. The more recent disturbances frequently bear metalliferous 

 veins, which give to the country its value as a mineral region. Copper and iron 

 are the chief minerals, and abound in nearly every section. Gold and silver some- 

 times occur. The Taconic of Michigan contains vast beds of iron ore. The ores are 

 magnetic, red specular hematite and soft hematite resembling the brown hematite 

 of other States. The magnetic and specular ores are the most prized, and usually 

 contain from 60 to 70 per cent of iron, and hardly a trace of phosphorus or 

 sulphur. (Phosphorus makes iron brittle when it is cold, and is therefore called 

 cold-short, though it is malleable when hot, while sulphur makes it brittle when 

 it is hot, and it is therefore called red-short.) The Lake Superior region is the 

 chief locality of the world for native copper. It is so pure the aborigines 

 manufactured it into implements. The copper-bearing rocks extend eastward 



