Skip to survey
Ghyll Rift SystemSheet 1 of 6BCRA grade 5c

Cave-survey society

Mapping the dark,
one passage at a time.

We survey the Ghyll Rift System by hand: a station, a bearing, a distance, a depth, again. Scroll to descend the section. The drawing builds itself as you go.

Coordinates
N 51 03 04 · E 3 43 12
Logged
Survey 12 Jul 2026
Datum
Entrance datum 0 m
0msurface · entrance
Descend
-20 m-60 m-100 m-140 mA1042°A4HallA7Sump

Station A1 to A4

The first passage

A crouching rift, dry and cold. The line runs ahead of us on the tape; the drawing follows the tape. Bearing holds around north-east; the floor tilts down the whole way.

Vertical section

Reading the depths

Each station is fixed to the last by tape, compass and clino. The depth is the honest part.

  • -12mRift head, station A2
  • -34mThe elbow, station A3
  • -68mPassage floor, station A5

Chamber · station A6

The hall

The passage opens and the tape runs out of things to touch. For a moment the drawing has nowhere to hold, and the line just hangs in the dark, waiting for a wall.

Terminal · station A8

The sump

-142m

Still black water, no far side. The tape goes under and the drawing stops with it. This is the bottom of the sheet, for now.

Field method

How a cave is surveyed

No lidar, no drone. A survey is a chain of measured legs between fixed stations. You believe the drawing because every line is a number someone read in the dark and wrote down.

  1. StationMark a fixed point. Every leg starts and ends on one.
  2. BearingCompass reading to the next station, in degrees.
  3. ClinoInclination up or down, which becomes the depth.
  4. DistanceTape length along the leg. Read twice, agree once.
  5. SketchWalls, floor and detail, drawn to the stations by eye.

The society

Join a survey weekend

Two days underground with tape and notebook. No experience needed, only patience and a steady hand. We will teach you to read a leg and add it to the sheet.

Join a survey weekend

A fictional society. This is a design showcase, not a real expedition.