The term bench mark, or benchmark, originates from the chiseled horizontal marks that surveyors made in stone structures, into which an angle-iron could be placed to form a "bench" for a leveling rod, thus ensuring that a leveling rod could be accurately repositioned in the same place in the future. These marks were usually indicated with a chiseled arrow below the horizontal line.
The term is generally applied to any item used to mark a point as an elevation reference. Frequently, bronze or aluminum disks are set in stone or concrete, or on rods driven deeply into the earth to provide a stable elevation point.
The height of a benchmark is calculated relative to the heights of nearby benchmarks in a network extending from a fundamental benchmark. A fundamental benchmark is a point with a precisely known relationship to the level datum of the area, typically mean sea level. The position and height of each benchmark is shown on large-scale maps.
The terms "height" and "elevation" are often used interchangeably, but in many jurisdictions they have specific meanings; "height" commonly refers to a local or relative difference in the vertical (such as the height of a building), whereas "elevation" refers to the difference from a nominated reference surface (such as sea-level, or a mathematical/geodetic model that approximates the sea level known as the geoid). Elevation may be specified as normal height (above a reference ellipsoid), orthometric height, or dynamic height which have slightly
This cache will take you to 3 benchmarks in the center of Walsall and then to a final location is outside the town centre approximately 2.5km walk away.
Stage 1 is a benchmark on the left hand side of a bridge
Lamppost to the left of benchmark which number do you report a fault to?
0800 A8C1BD2
This lamppost has a number E= Second digit of lamppost number minus first
Stage 2 is a benchmark on the left hand side of the Salvation Army building
Sally Ann’s – is open F0am – 2.30pm
It is open G days
Stage 3 is a benchmark on the face of the Guildhall
The Green Dragon Inn was first mentioned in 162J, it closed in 1C12
The final location is:
N52 A4.BCD W001 E(J-1)(C-1)GF
You can check your answers for this puzzle on GeoChecker.com.