986 Wisconsin Academy of Sciences, Arts, and Letters. 
gradual, and the whole range was originally heavily timbered. 
In the immediate vicinity of Duluth the forest has been re¬ 
moved, except in a few parks, which still retain some of the 
old pines. Fortunately, outside of the city limits there is a 
good growth of hardwood, and northward along the lake shore, 
more virgin conditions prevail. The rock is Archean-gabro, of 
volcanic origin. Similar rock formations occur in the Adiron- 
dacks and in the neighborhood of Baltimore, Md. In fact the 
Lake Superior basin itself may be regarded as a primitive de¬ 
pression of the earth crust, antedating the Huronian period. 
There are many intrusions of eruptive rock, arranged more or 
less concentric to the basin, with the newest nearest the lake, 
and it is thought that the depression is an ancient and deep 
seated centre of volcanic activity. 1 Faults occur in the rock 
formation, especially at Carlton, Minn., where the Huronic 
slates appear. It is here that the water of the St. Louis Biver 
finds egress to Lake Superior, rushing over the displaced ledges, 
and eroding a gorge of great extent and beauty. 
The whole North Shore Bange which really begins at Carl¬ 
ton, Minn., twenty miles up the St. Louis Biver, is cut by 
many small streams and rivers which drain the upland val¬ 
leys and swamps. These streams make the drop to the lake 
level, sometimes within a short distance. This produces a 
series of cascades, waterfalls, and rapids, rocky ravines and 
eroded ledges. Each of these streams has its own peculiar 
charm, and when heavily wooded afford to the bryologist as well 
as the angler, a paradise of interest. Within the city limits of 
Duluth the places referred to in this report are Oneota ravine 
with its bald peak, and canyon cliff; Spirit Lake ravine, with 
its narrow, deep perpendicularly-walled watercourse often 
bridged by old logs, and large rocks; Chester Creek and Lester 
Bivers preserved a's public parks, and still growing a rich 
hepatic and moss flora. Beyond the city along the north shore, 
at intervals of every few miles are the larger rivers, Sucker, 
French and Knife. On account of the accessibility of these 
places, the collecting done in Minnesota has been along these 
rocky water-ways. Swamps and bogs, and deep wood at the 
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