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ILLUSTRATIONS. 
PLatE XVI.—Continued. 
Fic. 4.—Sandstone from the Calumet Conglomerate, Calumet and Hecla 
Mine, Keweenaw Point. Detritus of quartziferous por- 
phyry, consisting of feldspar and quartz fragments and 
fragments of matrices; magnetite particles; rather large 
particles of basic rocks; native copper. Scale, 28 diame- 
ters. 
XVII.—Geological map of Keweenaw Point, Mich.........-....---.--..------------ 
XVIII.—Geological sections of Keweenaw Point, Mich .......-.---..-----.----------- 
XIX.—Geological map of the Porenpine Mountains, Mich.-.-..-----..-------------- 
XX.—Geological section illustrating the structure of the Porcupine Mountains, 
Mi clientes eeeuis ean eyae een a son en teeter ae Ne onl idawieive 
XXI.—Geological sections illustrating the structure of the Porcupine ea agit 
XXII.—Geological map of the region Berween the Ontonagon River, Mich. 5 “one Nu- 
np aN AOE) Wee s ocaeageao coo soc ar scdnbe ston o8ee aes 
XXIII.—Generalized geological sections of the region between Portage Lake, Mich., 
and the Saint Croix River, Wis-.s------.------..-.-....--. 
XXIV.—Map showing the positions of the exposures of Keweenawan rocks and Pots- 
dam sandstone along the lower portions of Snake and Kettle 
Gays Ni TNS aah nese cen Qocone os adisEeSno BessEadete noeeeS 
XXV.—Map showing rock exposures in the vicinity of the Upper Saint Croix River, 
INVA seo tet eee ee ence, ceter i inte a sions nae stele ele 
XXVI.— Geological map of the moeth west! coast of Lake Sun one So epee cee Onaaeconoe 
XXVII.—Geological map of Isle Royale and the neighboring mainland -..------.------ ; 
XXVIII.—Map of the Lake Superior Basin, designed to show the structure and extent 
of the Keweenawan synclinal ...--........--.-.--...----- 
XXIX.—Generalized geological sections of the Lake Snperior Basin --.-..-.----------- 
Fic. 1.—Outlines of coast hills for 20 miles above Grand Marais-.-..--..--..-.----------------- 
Fic. 2.—Surface contour and arrangement of beds at Eagle Harbor. Represents a distance of 
PING Tea Aa Se encoce eco sacs coteeg es S016 OeL boo SBSse are SegoD So Se ssoCeacUmeoecp 
Fic. 3.—Map of exposures in the vicinity of west branch of Ontonagon River, T. 46, R. 41 W., 
MOTO Tin aps cote anon ESS SOBER IASI SOS5 BAS 50 BA05 HSC EE COC OoSE Oper EE ey caso sace ee EOS 
Fic. 4.—Map of exposures on upper Carp River, Porcupine Mountains. One inch= 90 paces. 
PIG) 5.—Cross-sectionon line GD) of Big, 42, 22-22 o ~~ oe cae eo = Ore owe ann =~ eee 
Fig. 6.—Section on line A B of Fig. 4 ......-. ---..<---- - << 23 1s ons 2-32 eos ee one 
Fig. 7.—Showing unconformable contact between Keweenawan diabase-porphyry and Pots- 
dam sandstone at Taylor’s Falls, Minn.; after Chamberlin -.-..--..---.---------- 
Fic. 8.—Map of exposures on Kettle River, Sec. 22, T. 41, R.20 W., Minn. Scale, 4 inches to 
LARGO MT )e, sone ecodSE BeOS Ae COS RSE Sa RS BOOsod CE SE oeOsSece clas pec cee EeSe DoS eso UbnooS 
Fic. 9.—Section on line AB of Fig. 8. Scale horizontal, 8 inches to the mile; vertical 300 
feet to) the wnC Ws aete sama ae las ae ne eters oe wie lel eieeieininie [-limiaisinl oS iei> sie siemn=l =e mie 
Fie. 10.—Section on the gorge of Black River, Bowplas (Cotnings, Wit conecs sooesscseseedaoras 
Fic. 11.—Section in the gorge of Copper Creek, Douglas County, Wis.-..-.------------------- 
Fic. 12.—Sketch of a cliff-side near Agate Bay, Minn., illustrating the warped bedding of 
layers. The dip is toward the observer -.-.--. --------------++---++--+--+-------- 
Fic. 13.—Sandstone ‘‘ veins,” Minnesota coast—plan. ---.-- - “Sno caas sseocoseceensancdcccsbstes 
Fig. 14.—Sketch of cliff on Minnesota coast, showing penetration of fissures of amygdaloid by 
BANGStONG eee cee ees = ane = oo www veins aeelna nina welnienm oman ae wenninelmerwensecner 
Fig. 15.—Dike, two miles below Lester River, Minnesota coast ..-.------------------+-------- 
Fic. 16.—Generalized section of Portage Bay Island, Minnesota coast.-....------------------- 
Fig. 17.—Sketch-map of rock exposures near Split Rock River, Minnesota coast, T. 54, R.8 W- 
Fic. 
18.—Sketch-map of rock exposures in the vicinity of Beaver Bay, Minnesota coast, T. 55, 
XV 
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