70 
GEOLOGY OF NORTH AMERICA 
The second group of the Eruptive rocks consists of trap and greenstone , that have made their 
appearance during the New Red Sandstone epoch ; they have spread over this formation , filling up 
the faults, and sometimes capping the strata, without causing much disturbance in the stratification. 
The trap contains numerous veins of pure copper mingled with pure silver, as well as copper, 
zinc, lead, and other ores. The famous copper mines of Lake Superior are among this trap. It 
is found on the Magdalen islands, on the northern coast of the bay des Chaleurs, on both shores 
of the hay of Fundy, in the valley of the Connecticut river, and in the New Red Sandstone basins 
of New Jersey. The palisades of the Hudson river, near New York, are formed of this trap , which 
here has the appearance of basalt. At Lake Superior it is found on the islands of Michipicoton , 
Stignace, du Pate and Royale, at Thunder Cape, near Fort William, and near Kakabekka falls; 
it forms the greater part of Keevenaw point, and the Ontonagon mountains, and occurs again on 
the river S' Croix, and near the rapids of the Upper Mississippi. The Rlack mountains, west of 
Fort Laramie, and the vicinity of Fort Webster or Coppermine in New Mexico, are also of this 
formation. 
Finally, the third group of Eruptive rocks includes all the varieties of rocks produced by ac- 
tive or extinct volcanoes. No volcanoes exist in the Eastern or Atlantic region, hut they are 
found in the Central and also in the Pacific region. They run from east to west, beginning with 
Raton mountain near the sources of the Canadian river, then the Cerrito between Santa Fe and 
Algodones; Mount Taylor, between Albuquerque and Fort Defiance, is an enormous extinct vol- 
cano, whose lava streams extend in all directions round the principal cone, fora distance of thirty 
miles. West of the Pueblo de Zuni are two large volcanoes, one of which attains gigantic pro- 
portions, its highest summit being more than thirteen thousand feet above the level of the sea. 
Five or six volcanic cones are grouped together in Soda lake , where the Mohavee river empties ; 
and north-east of the Great Salt Lake, near Fort Hall, there are two large volcanoes called Three 
Bates and Three Tetons. There is still another series of volcanoes running from north to south, 
following the line of the Sierra Nevada. One of these volcanoes is in Lower California , opposite 
the town of Guaymas, another in the Sacramento valley, where it forms isolated mountains, cal- 
led Bates. Farther north is Shasty Peak, then come Mounts Hood; S* Helen, Rainier, and Baker, 
in the Cascade Range. The three last are still in activity , and Mount Baker especially sends forth 
frequently large lava streams. 
Sauns (Jura) , July 1855- 
