Cross-section station and channel station: Station location
is referred to 0+00 at the fence line at mouth of main channel.
For example, 3+00 means 300 feet upstream from the fence line.
Stations along gully at which the cross sections A-B, C-B, and E-D
occur are respectively 1+60, 2+50, and 7+20 feet.
LB BM description: LB means left bank, facing downstream.
LB BM is the left-bank bench mark, or reference point. The term
"bench mark (BM)" refers to a 4-foot steel rod, 1/2-inch diameter,
driven into the ground and protruding about 6 inches. All bench marks
have a brass identification tag attached which is imprinted with the
bench-mark description, elevation, and LDG (an abbreviation for Last
Day Gully).
RB BM description: Right-bank bench mark, or reference point.
See also LB BM description.
LB BM and RB BM elevation: Elevations, in feet, are referenced
to an arbitrary elevation of 100.00 feet at the top of BM-A. The
adding of 5,000 feet gives the approximate elevation above sea
level.
Distance from LB BM: Distance, in feet, from left-bank bench
mark toward right-bank bench mark.
Elevation: Bench-mark elevations refer to the tops of the
bench marks, and other elevations refer to the ground surface.
Yearly variations in elevation for a given position on a sloping surface
may not necessarily imply erosion or deposition of that amount because
slight leeway in lateral placing of level rod gives variation in
elevation. However, for flat or nearly flat surfaces, such as the
channel bed, variations probably record actual changes. See also
LB BM and RB BM elevation.
Erosion: Actual values, in feet, measured from pins driven into
the ground. Negative values indicate deposition rather than erosion.
