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There are high-tech and low-tech ways to measure the ground surface and to record earthworks and structures. The choice of method will be based on the size and complexity of the area to be investigated and the available equipment. 

The simplest is to use three tape measures to create a grid using the 3,4,5 method. Measuring a position from a grid using this method is called ‘off-setting’. Based on simple geometry, a 90 degree right angle can be created by making the tapes work together as a triangle with sides of exactly 3, 4 and 5 metres. When the long side (the hypotenuse) is 5 (or a multiple of 5 - as in Pythagoras’s theorem), 3 and 4 (or their multiples) should therefore meet at a right angle. Vertical heights, such as slopes, can be measured using tapes and measuring rods in a step-like fashion.
Once a survey grid has been created across a site, and its intersections marked with canes or pegs, a detailed plan of the earthworks within the grid can be created using a plane-table. This is a flat drawing board set on a tripod exactly over a known point, to which a measuring tape is attached and extended by one surveyor to each of the points which are to be recorded. A simple instrument like a ruler with a rifle-sight on top called an ‘alidaide’ allows the operator to sight along the tape to a vertical measuring rod at the recording point, and to draw a line at 1:10 or 1: 100 scale on the plan. Finishing the plan is a dot-to-dot and line-to-line illustrative exercise. Occasionally, a ‘self-reducing alidaide’ is used, which can provide vertical as well as horizontal measurements. Regarded by some people as old-fashioned and out-moded by Total Stations, but still much-valued by their admirers, these are now not easy to get hold of.