iW S. i S^tL if»Y 



PRELIMINARY REPORT 



ON 



THE DREDGING IN LAKE SUPERIOR. 



New Haven, Connecticut, October 9, 1871. 

 General : I have the honor to submit herewith a preliminary report on the dredging 

 carried on, under your instructions, in Lake Superior, during August and the early 

 part of September. I regret that the short time since the dredging was completed has 

 been insufficient for more than a hasty examination and review of the materials col- 

 lected, and that consequently the following report is quite imperfect as regards the 

 microscopic species. 



I wish here to acknowledge the generous assistance of Professor Verrill, who very 

 kindly procured dredges and other apparatus for me, and who has since determined the 

 worms and aided me by advice in many ways. 



Very respectfully, your obedient servant, • 



SIDNEY I. SMITH. 

 Brevet Brigadier General C. B. Comstock, 



Major of Engineers, in charge U. S. Lake Survey. 



EEPOET. 



The dredgings were all made from the steamer Search, and were carried on wholly 

 by hand. The dredges used were like those commonly employed in marine dredging, 

 with the addition of an inner bag of embroidery canvas, which was found necessary 

 to retain the exceedingly fine clayey mud encountered at nearly every haul. Owing to 

 rough weather and the employment of the steamer for other purposes, the dredgings 

 were not so numerous as might be expected from the length of time through which 

 they were distributed. Enough, however, was done in the deeper parts of the lake to 

 show fully the composition of the bottom, and to indicate clearly the nature of the 

 deep-water fauna of the lake. 



The following list will show the localities at which dredgings were made, the depth, 

 and the composition of the bottom : 



Simmons's Harbor, on the north shore of the lake, about twelve and one-half miles 

 north-northwest of Otter Island, August 9, IB to 15 fathoms, bottom of fine sand with 

 scattered tufts of a small alga of the genus Cladophora. 



Five miles off Simmons's Harbor, August 11, 60 fathoms, soft bluish clay. 



Among the Slate Islands, August 14, while at anchor, two hauls : First, 12 to 14 

 fathoms, sand with a little fine mud. Second, from the other end of the steamer, 6 to 

 8 fathoms, sand, gravel, and small stones, with some mud. 



On a line from the Slate Islands toward Stannard Rock, August 15, four hauls were 

 made as follows : First, about eighteen miles south of the western end of the islands, 

 105 fathoms, soft clay. Second, about thirty-five miles from the islands, 169 fathoms, 

 the deepest point yet found in the lake, very soft, light-drab clay, with small pieces of 

 rotten wood. Third, about forty miles from the islands, 116 fathoms, bottom same as 

 in the last haul. Fourth, about fifty-seven miles from the islands, 159 fathoms, very 

 soft clay. 



On a line southeast from Passage Island, off the east end of lie Royale, August 18, 

 hauls were made at five points : First, about six miles out, 47 fathoms, soft reddish 

 clay and sand. Second, about fifteen miles from Passage Island, 129 fathoms, soft clay. 



