GLO Surveying
02/04/2015
U.S. Rectangular System
Structure
• Meridians & Baselines:
• 35 principal meridians and 32 baselines
• Meridian – line runs straight N-S
• Baseline – line perpendicular to meridian
• Principal Meridian – generally established 1st.
• Standard Parallels
• E-W lines parallel to baseline at intervals of 24 miles N and
S of the baseline.
• Guide meridians
• Lines running N-S and 24 miles each side of P.M.
This 24 mile square is a Quadrangle and contains 16
Townships
Baselines run @ 90° to P.M.
Point of intersection (BL&PM) often called
Cardinal Point.
Townships
• Township lines are E-W lines 6 miles apart north or
south of the baseline.
• Range lines are N-S lines 6 miles apart east or west
of the principal meridian.
This 6 mile square is called the Township
• Townships are divided into 36 – 1 mile square
sections.
• Numbering system called boustrophedonically
Error Corrections
• Correction Lines (Standards of Parallel)
• Each acts as a new Baseline for townships to the North.
• Due to the convergence of meridians, compensation is needed.
B.L.M. Rules
1. Boundaries of the public lands, when approved &
accepted are unchangeable.
2. Original townships, section, and ¼ section corners must
stand as the true corners which they were intended to
represent whether in the place shown by field notes or
not.
3. ¼, ¼ section corners not established in original surveys
shall be placed on line connecting section & ¼ corner &
midway between, except in the north and west ½ mile of
townships & fractional sections.
B.L.M. Rules
4. Center lines of a section are to be straight, running from
¼ corner to ¼ corner with center of section at the
intersection.
5. In a fractional section where no opposite corresponding
¼ corner has been or can be established, the center line
must be run from proper ¼ corner as nearly cardinal as
parallelism with sectional boundaries allow.
Exterior Township Lines
1. Celestial observations to determine variance is made at
least every 12 miles on east-west lines and at the end of
18-24 miles on north-south lines.
2. Method: Township line (baseline) established due eastwest across south boundary of tract to be surveyed;
monumented every ½ mile; from township corners run &
monumented range lines, establishing temporary
township corner at six miles; at the far corner establish a
post and run line east-west; township corners established
at intersection points by running line due east or west to
close; corner will be the intersection with distance to
temporary post measured.
Exterior Township Lines
3. Surveyor must prepare a map or diagram of lines to a
scale of 4 miles = 1 inch.
4. All measurements to be horizontal.
5. Monuments other than standard post: Mound – 2½’ high
with 4’ base with angles in direction of cardinal points
with stone of 3-4 lbs in center of a few handfuls of
charcoal, mound often covered with sod.
Subdivision of Township
• The east tier of sections run, then return to south line
and run next tier with east tier run until the last west
tier.
General Instructions to Deputy Surveyors in
Illinois & Missouri (1834)
1. Monuments
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Post: Standard but 2’ in ground
Stone: 7”-8” deep, 12” wide, 14” long and 3” thick.
Township corner 5” diameter & section corner 4” diameter.
Must be squared off at top.
Place stones so corners correspond to cardinal directions
Mound: place at least 2 quarts of charcoal at least 3” below
surface over which mound is placed.
 Township corner mounds: 3’ high, 5’ square at base and 2’
square at top.
 3 stones (at least 5” square and 3” thick) in top of upper stone
at least 3” below surface.
General Instructions of 1843
• Required that section corners on west side of
township be run and corrected thus eliminating
double corners on the west side of township, but
double corners still exist on the north side of the
township.