ECOLOGY OF NORTHERN MICHIGAN. 21 



referred to in this report are, unless otherwise specified, above the level of 

 Lake Superior. The elevation above sea level may be obtained by adding 

 601.19 feet to the given altitude (Wright, '05, p. 36). 



The first ridge, rising from the shore of Lake Superior, reaches a height 

 of 850 to 900 feet within a mile and a half. It then decends abruptly 400 

 feet into the valley of Carp river. This cliff consists of about 200 feet of 

 vertical face, with a steep bare talus slope at the bottom which is composed 

 of angular fragments of trap and sandstone rock weathered from the cliff 

 above. As may be seen from the contour map, this talus slope grades down 

 into the flood-plain of Carp river, except on Sections 21 and 22, T. .51 N., 

 R. 43 W. ; here the river widens out to form Carp lake and the talus decends 

 into the lake. This great cliff extends nearly continuously across T. 51 N., 

 R. 43 W., a distance of over six miles. Beyond Carp river the mountains 

 rise in steep ridges and knobs, but with no precipitous cliffs, to the valley 

 of the Little Carp river. 



About three miles south of the west end of Carp Lake, on T. 50 N., R. 

 44 W., Section 2, Little Carp river widens out to form Little Carp Lake. 

 This lake, which marks the end of the line of survey, is about half a mile 

 long and a quarter of a mile in width, with very irregular shores formed 

 by the surrounding hills. 



The mountains are most easily reached from Ontonagon, Michigan. From 

 here to Union Bay, there is a good but sandy road. After leaving Union 

 Bay the road enters the mountains and runs along the north slope of the 

 first ridge. This slope is terraced by old beaches which mark higher levels 

 of Lake Superior, and the road ascends the mountains by these natural 

 driveways, ascending from one beach to another in the less difficult places. 



It is important to bear in mind that the present topography is not in a 

 static condition but is being constantly changed by the forces acting upon 

 it, and that it will continue to be changed and modified until the land has 

 been reduced to base-level. It must also be borne in mind that forms of 

 life are dependent on the environments formed by the physical conditions. 

 These facts are as important from the ecological as from the physiographic 

 standpoint, for with changes in the physical conditions there are associated 

 changes in the dependent habitats. The present conditions are not sufficient, 

 therefore, to explain the distribution of the present biota, and the past con- 

 ditions can only be understoo'd through a knowledge of the action of present 

 forces in producing changes in the environments. It is for this reason that 

 the present geological and topographical conditions have been considered. 



4. LOCATION OF THE FIELD STATIONS. 



The line of survey began at Lake Superior on the north and south line 

 of Sections 11 and 12, Township 51 North, Range 43 West, and from here 

 ran southwest up the north slope of the first range to a saddle in the crest 

 at an elevation of 750 feet on Section 14. From this point a transverse line 

 was run along the top of the range, to the west on Sections 14, 15, and 21, 

 and to the east on Sections 14 and 13. From the saddle on Section 14, 

 the main line was continued due south down the escarpment on the south 

 side of the range, across the valley of Carp river to the east and west line of 

 Sections 14 and 23. From this point it was run southwestward across the 

 intervening ranges to the top of Government Peak on Section 27. Another 

 line was run down the valley of Carp river from the north and south line of 

 Sections 24 and 25 to the West end of Carp Lake on Section 21. Here it 



