As promised, here is my cave survey (mapping) post. Buckle in, it's a long, but informative ride.
Let's start off with the sheer amount of caves that are unmapped or undiscovered. We find hundreds of new caves every year across the world. It's also true that the deepest and longest caves in the world may not yet have been found, or if they have, they may not have been fully explored (see Tears of the Turtle Cave). We have no idea. With humans having stepped foot on the moon, the tallest mountains being long conquered, and the deepest depths of the oceans known about, even if they aren't directly mapped, caves may very well be the "last frontier." They are some of the final places where you can enter and be the first person who has ever been there.
📸 me exploring down a passage that no human had ever been.
As cavers we have a responsibility to map these places, and map them well, that way others can come back for recreation, research, education, or any of the other many purposes caves serve.
Mapping a cave properly means you want to take note of not only the 2d overhead "plan" view of the cave, but also the "profile" view (i.e. what does the passage look like as you're looking down it).
Here's an example of what a plan view looks like. It's like of we cut the roof off the cave. You'll also notice that there's lots of details and markings. These are established cartographic symbols in the caving community and while they might look random, if you know what you're looking at, they're very helpful. For example, by looking at this map I can tell that the floor is sand, there's breakdown (fallen rocks) in the center of the room, slopes next to the breakdown, and several domes in the ceiling.
The profile view is typically expressed by drawing a line from the plan view to the profile. This is a good example because the small piece of breakdown you can see in the plan view is visible in the profile view!
Ok, so that's all well and good, but how do we get the plan and profile views? What sort of measurements are we taking to create these maps? Great question dear reader: distance, azimuth, and inclination. Distance is feet or meters, azimuth is the compass bearing (i.e 120 degrees), and inclination is the slope (i.e. +15% or -15%). Nowadays, we use lasers, but these measurements used to be done with steel tape and a compass-clinometer. A significantly more difficult and time consuming process. For our purposes I will be sticking to laser surveys, but if you're interested I encourage you to look into earlier mapping efforts.
📸 A popular compass clinometer combo made by Suunto.
📸 A modified Disto Leica made to work for the caver's purposes (modifying an existing disto costs ~$1,000 USD). Friendships have been ended over broken distos.
These instruments measure distance, azimuth, and inclination from between survey stations. A survey station looks something like this:
📸 an example of a survey station
There will be a dot to shoot the laser at, a survey designation (in this case C A C), and what number the station is in that designation. In most cases, these stations are set with whiteout or nail polish. In desperate situations where you run out of your whiteout supply, there are alternatives such as carving into the rock and placing flagging. As you can see, this is not as effective. Should the flagging ever fall, the station would become easy to miss.
📸 A station scratched into the wall with orange flagging placed nearby
📸 me applying a station to a cave wall
Now, for the actual process of the survey, teams will typically consist of two to three people. One person will act as the "point" they will choose the route for the survey and apply survey stations to the wall. The second person operates the instrument and shoots from station to station. The third person is the sketcher, they sketch down the passage as it comes using the measurements provided by the instrument person and their own eyesight. The positions of point and instrument can be condensed into one job if needed.
The sketcher is taking down measurements in their notebook, which looks like this:
📸 typical sketching book with a plastic compass and ruler.
Using a set scale (i.e. 1 inch = 20 feet), the sketcher will draw in the measurements as they come, using the plastic compass and ruler to draw everything in to scale on the paper. Becoming a good sketcher takes a long time and lots of practice, and a poor sketcher can easily lead to confusing, incorrect maps. For this reason, sketchers are highly sought after for the cave survey, and the best way to ensure that you continue being invited to projects is to become a good sketcher, or perhaps owning a disto given the high price tag.
After the day is done, the sketcher will turn their map and measurements into the cartographer of the project. This person will then make the finished version of the map combining all of the different sketches taken into one cohesive unit. This is also a sought after skill as it requires some programming knowledge, patience, and some art skills. A pretty map that is also accurate is highly sought after.
So, to review, the basic process is that one person sets a station using whiteout. The station will contain a dot, a survey designation, and a number. The instrument person will then shoot to this station from a preexisting one. After completing the shot, they will shout back the distance, azimuth, and inclination to the sketcher. The sketcher will in turn record these measurements in their book, and, using their ruler and compass, translate these measurements onto paper. At the end, the measurements and sketch will be given to the cartographer who makes the finished map!
Survey is awesome and I highly recommend anyone considering caving to also get into cave survey. You'll get to go to places that nobody else does. The picture below is from a part of mammoth cave not open to the public, but because I was surveying, I got to see it:
I will leave you there, with the added caveat that I haven't said nearly as much as I could have and that each position has its own intricacies. This is the basic introduction though!
