LAKE SUPERIOR DIVISION.
INSTRUCTIONS.
1. Ordinarily at least two pages of this book will be devoted to one section. On
tie left-hand page, place a map of as much of the section as has actually been seen.
Denote rivers, lakes, marshes, etc., by the usual topographical signs. Denote the
ledges of rock, when no structure is made out, by cross-hatching, making the cross-
hatching cover as nearly as possible the areas oocupied by the exposures. If the
iock is a massive one, but still more or less plainly bedded, use the same sign with
a dip arrow and number attached, showing the direction and amount of the dip.
Denote a shaly or other very plainly bedded ledge by right parallel lines, and a ledge
having asecondary structure by wavy parallel lines running in the direction of the
strike, with dip arrow and number attached as befoie. The greatest care must be
taken to avoid confusing slaty or schistose structure with bedding, and in all cases
where there is the least doubt about the true bedding direction, indicate it by a
juery. To each exposure on the face of the map attach the number of the specimen
representing it. In mapping the section count each of the spaces between the blue
lines as 100 paces, and twenty of these spaces to one mile, or 2,000 paces. Usually
the southeast corner will be placed at the bottom of the page, or at the first black
'1ne above the bottom of the page, and at the right-hand side. If, however, for any
ieason, it is desirable to show portions of an adjoining section, the southeast corner
may be shifted up, or the map may be turned around and the north placed at the left-
hand side of the page. The ruling of the left-hand pages is also arranged so that,
if desirable, a larger or a smaller scale can be used, eight inches, two inches, one
inch, or one-half inch to the mile. With the two-inch scale, the squares outlined
black represent sections, and those in red, quarter sections and "forties," while
Ihe space between the blue lines is 200 paces.
2. On the right-hand page place the notes descriptive of the exposures. Begin in
each case with the number of the specimen, placing the number on the left-hand
side of the red line, after which give in order on the right of the same red line tho
position of the ledges as reckoned in paces from the southeast corner of the section
aid the dip and strike when observable, the latter always being expressed from the
north; for instance 4025, 250 N, 300 T., Strike, N. 780 E., Dip 50' S. Then follow
with a full description of the ledge. When topographical maps are used for
locations this paragraph applies only in part.
3. Collect a specimen fromn every ledge, or wherever there is a change of rock on
any one ledge, taking care to get fresh material, unless for a special purpose the
weathered sUrface is desired. In case of trips made on foot or in canoes, for long
distances, neighboring ledges, unquestionably of one kind of rock, need not be
pecimened. The position and extent of the ledges not specimened should be
marked on the map, with notes that each is of a rock identical with specimen
so-and-so. Under the same conditions small-sized specimens, trimmed to a uniform
size of 2 x 21 x I inches will be allowed, but in all other cases large-sized specimces,
trimmed to a size of 3 x 4 x 1 inches, must be selected, in accordance with section 3,
chapter IV, p. 44, Regulations of the U. S. Geological Survey. Specimens should
not be placed together without protection in the collecting bag, as the fresh surfaces,
important in determining the character of rocks, are thus destroyed. They should
be damaged by no temporary mark, but the numbers should be at once marked in
at least two places upon the inclosing paper or cloth bags. Specimens may be
permanently marked in camp by painting the numbers upon them in white upon a
black background, using Silver White and Ivory Black oil tubes for color, with
turpentine as a diluent.
4. On the last twenty-five pages of the book give, as may seem desirable, a general
account of the examination of the region mapped in the previous pages, correlation
of observations, sketches, cross sections, etc.
5. Forward this note book as soon as filled as registered mail matter to C. R. Van
I lise, U1. S. G(eolopist, Madison, Wis. -717