Cave survey

A cave survey is a map of all or part of a cave system, which may be produced to meet differing standards of accuracy depending on the cave conditions and equipment available underground. Cave surveying and cartography, i.e. the creation of an accurate, detailed map, is one of the most common technical activities undertaken within a cave and is a fundamental part of speleology. Surveys can be used to compare caves to each other by length, depth and volume, may reveal clues on speleogenesis, provide a spatial reference for other areas of scientific study and assist visitors with route-finding.

Traditionally, cave surveys are produced in two-dimensional form due to the confines of print, but given the three-dimensional environment inside a cave, modern techniques using computer aided design are increasingly used to allow a more realistic representation of a cave system.

The first known plan of a cave dates from 1546, and was of a man-made cavern in tufa called the Stufe di Nerone (Nero's Oven) in Pozzuoli near Naples in Italy. The first natural cave to be mapped was the Baumannshöhle in Germany, of which a sketch from 1656 survives.

Another early survey dates from before 1680, and was made by John Aubrey of Long Hole in the Cheddar Gorge. It consists of an elevational section of the cave. Numerous other surveys of caves were made in the following years, though most are sketches and are limited in accuracy. The first cave that is likely to have been accurately surveyed with instruments is the Grotte de Miremont in France. This was surveyed by a civil engineer in 1765 and includes numerous cross-sections. Édouard-Alfred Martel was the first person to describe surveying techniques. His surveys were made by having an assistant walk down the passage until they were almost out of sight. Martel would then take a compass bearing to the assistant's light, and measure the distance by pacing up to the assistant. This would equate to a modern day BCRA Grade 2 survey.

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