382 The American Geologist. December, 1897 
beds siaiilar in character and perhaps also following each 
other closely ill point of time is quite possible. But that 
every lateral plain should represent a division between two 
successive tlows is not in keeping with any single point of ev- 
idence. At other outcrops the thickness of the flows appears 
to be much less than at Taylor's Falls, but at no place is there 
a better opportunity for the study of so many flows in succes- 
sion each of which is accessible throughout its entire thick- 
ness. Everywhere the topography is the feature first inviting 
investigation, but at no point so well as at the Dalles is the 
topography so perfect a guide to the exact divisional planes 
over so great an area. 
Thickness. The total thickness of the Keweenawan at this 
point is not known. Accepting the dip of 15 degre^'es as fairly 
constant over the whole district, 4,000 feet will represent ap- 
proximately the thickness of the rocks in sight. What the 
total thickness of the Keweenawan is at this locality is hot 
known. The Stillwater w"ell penetrated these flows from 717 
feet to 3,408 feet of its depth.* 
Folds in the Keweenawan Bocks. Adjacent areas from 
which data are obtainable bearing upon the Keweenawan sur- 
face, are the Kettle river outcrops at Chengwatana and vicin- 
ity, about 27 miles north, and at Stillwater, an equal distance 
south of the Dalles area. The Kettle river outcrops dip tow- 
ard the east or south of east at a high angle. Seven or eight 
miles west of the St. Croix river this angle reaches 50 to 75 
degrees, but passing eastward the dip flattens rapidly until it 
becomes very low, 10 to 15 degrees, at the outcrops along the 
St. Croix river itself .f These exposures are not over 900 feet 
above the sea. 
At Taylor's Falls the outcrops show a dip of about 15 de- 
grees toward the south of west at an elevation of 1,100 feet. 
At Stillwater the Keweenawan igneous rocks were reached 
in It deep well at a depth of 717 feet,J which makes the sur- 
face of the igneous rocks coincide very nearly with mean sea 
*A. D. Meeds, The Stillwater Deep Well, Bull. Minn. Acad. Nat. 
Sciences, vol iii, no. 2, 1891, p. 274. 
IR. D. Irving; The Copper-bearing Rocks of lake Superior, U. S. G. 
S., Monograph V, 1883, pp. 242-245. 
XLoc. cit., Bull. Minn. Acad. Nat. Sci., vol. in, no. 2, 1891, p. 274. 
