12 The American Geologist. July, 1895 
substaj^e, enlarged two diameters. It is somewhat 3'ounger than 
Clarke's fig. 8 and belongs to a larger specimen, but is nevertheless in 
the same substage of growth. In Clarke's figure the sheath is more 
shrunken in proportion and shows the ai)i>roaching termination of the 
ananeanic substage. Tlie triangular space between the first and second 
endocones is filled with Ihe loose organic deposit of the ])aranepionic 
substage which plugged up the endosiphon of the metanei^ionic sub- 
stage. The second endocone has a dense structure at the apex and be- 
longs entirely to the ananeanic substage, as shown in this and Clarke's 
fig. 8. Enlarged -f- 2 diameters. Locality, Minneapolis. 
Figs. 3 to 6. Clarke's original of his fig. ?,. enlarged about 2.3 to show 
details. This is a siphon belonging to a somewhat longer and older 
specimen than his fig. 1 when complete, and is perhaps at the begin- 
ning of the gerontic stage. Fig. 3 shows the shell on the venter forming 
the outer wail of the siphon and the abrupt termination of the sheath, 
which is larger and blunter in that of fig. 1 at a younger stage of 
growth. 
Fig. 4 is the same specimen from the front, showing relations of shell 
to tlie .septa and funnels on the left. Fig. 5-(i the same from side and 
back . 
[Crucial points in the geology of the L.\ke Superior region. No. 5.] 
STEPS OF PROGRESSIVE RESEARCH IN THE 
GEOLOGY OF THE LAKE SUPERIOR REGION 
PRIOR TO THE LATE WISCONSIN 
SURVEY. 
By N. H. Winchell, Minneapolis, Minn. 
Having now briefly noted the leading concurrent geologic 
events of tlie Taconic in North America as they are known to 
have occurred in regions surrounding the Lake Superior re- 
gion, it is next in order to give more close attention to the 
Lake Superior region itself. The geological literature of this 
region may be separated into two parts, based on a historical 
datum, viz., the Wisconsin geological survey concluded in 
1879 and full}^ published in 1883. 
American geological opinion, while in the main making an 
onward advance in correct interpretation, has been oscillatory 
on more subjects than one. This has been owing in no small 
degree to the tendency of the human mind to overestimate its 
own achievements. When some new fact in science, or some 
new understanding of a group of facts, has been vividly por- 
trayed and applied by some new investigator he has some- 
times given such wide scope to the new truth that it has been 
