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From javacavemaps
Caves are cavities in the earth's surface. Yes, the "Lithosphere". Caves can be man-made as in mines. Some crazy folks build houses in caves such as the Arkansas Cave House, and you can rent it for weekends. But the ones speleologist seek are created by natural geological processes. These caves can be one of several natural types: bluff shelters or overhangs, fractures, erosional and solutionary. The first three are fairly obvious. I shall define the third type
Solutionary caves are those created mostly from chemical reaction of acidic rain or ground water with base rock. Rock can be defined as Igneous, Metamorphic or Sedimentary. Sedimentary can be broken into Sandstone, Shale and Limestone or Karst. Karst areas are subregions of limestone. Maps called Geoquads can be obtained from your local governmental Geologic commission (i.e. Arkansas State Geologic Commission) which show where the various rock types come to the surface. Limestone or Karst (old ocean beds and lake beds) form these layers. Of the total land surface area roughly 10% are areas of Limestone or Karst. Of that 80% is Limestone and 20% Karst. Depending on which geologic authority you are talking to, the percentage of karst may be higher. For example some Geologist feel that the north Arkansas USA region is not karst, while local geologist feel it is. Limestone can be shaley in formation and can otherwise be of a type that does not produce much if any chemical solutionary action. Karst is typified by areas that contain large caverns, rooms, pits, depressions, sink holes etc. Non-Karst would be areas where you would not find caves or sizable caves or other chemical solutionary action of any size or given densities of these features. In other words karst would be limestone areas where you would most likely find caves. Non-karst would be less likely or not likely at all to find caves.
These limestone layers were formed from the skeletal remains of dead sea creatures. As a result of this composition they are alkaline in chemistry, known as Lime. Lime is a chemical base that is readily soluble in acidic water. Rain water can become acidic from various chemicals floating around in the atmosphere or decaying plants, especially leaves and evergreen needles. This makes that rain or run-off water act even more quickly on the Limestone rocks due to the actions of acid-base chemistry.
This brings us to the point that large caves of any size occur in these alkaline based rock layers. As rain water percolates through the ground it sometimes concentrates the acid. This forms Pits. Other times tubes form. This can form quite large systems such as Mamoth-FlintRidge in Kentucky, USA, 350 miles of passage known to be the longest mapped cave in the world. Or in New Mexico, USA, Lechuguilla, 5th longest cave in the world and still mapping 122 miles and counting. Lechuguilla is also the deepest cave in the United States at 1600 feet. As caves form, the acidic water picks up calcite from the stone and this is deposited in various locations where the nature of the water changes, such as drips. This makes stalactites and stalagmites and columns. In other places rimstone dams form pools. Yet other places form bacon strips and water under pressure form helectities. These formations have various colors depending on the amounts of other minerals.
Anyway the whole point here is people like to go visit these caves to see the pretty formations and otherwise see whats there. Also its nice to have very good maps of known caves in the event that some stupid teenagers get lost in them. Or also in the case of cave rescues which happen from time to time. In these case the local authorities are of little use. Cavers and their maps are the best bet.
National Speoleological Society or caves.org also NSS is the United States National caving organization. If you join you will get a monthly magazine with some nice photos, maps, and lots of (scientific data that seems useless to most normal cavers). You will also get a yearly accident report which list all accidents in USA and Canada that members report. Local caving clubs are called "Grotto's", which also happens to be another word for cave. Usually a state has several Grotto's. There are also Regional clubs that encompass a tri-state area. Anyway if you want to get into caving, learn the rules. As with anything dangerous, caving can be as dangerous as you care to make it. Manage the risk by learning safety. Contact the NSS for more info.
Not to get down to the point about mapping caves. There are no modern methods where we scan the cave as we walk with electronic devices then a computer auto-generates a map for us. Caves are very harsh environments and we use 100' tape, Compass and Clinometer. We also use a sketchbook to take notes on measurements and draw sketches of walls and features. A computer is then used to draft the maps using some form of vector software. CAD software is usually mechanical looking and not very artsy looking. Pixel editing software requires too much work in comparison to Vector software. Vector software is much better for drafting cave maps for several reasons. The primary reason is the artistic look and style that can be achieved. We also use the computer to calculate certain data from the survey lines for use in this software. For example cave walls and features are drawn around line plots. Line plots form the skeleton or frame.
A survey line is any two points in the cave. Each end is called a Station and is given a name such as A1, A2, A3, A4 etc. Between stations there are five essential readings that are recorded: forward azimuth, a back azimuth, a forward clinometer, back clinometer and distance. These five readings give us all the necessary data to plot a topographical map of the cave. The next few paragraphs explain how this is done.
The forward azimuth is the compass direction from one point to the next point in the series (i.e. A1 to A2) expressed as a number 0.00 to 359.99. The back azimuth is the same as the forward azimuth except it is the reverse, that is from A2 to A1. The clinometer measures the vertical angle of ascent or descent from one point to another in the the series (i.e. A1 to A2). The forward clinometer would be the vertical angle from A1 to A2 and the back clinometer would be the vertical angle from A2 to A1. Clinometer readings are expressed in degrees from horizontal (or level), such as -10.25 or +5.64, with a negative number indicating decent and a positive indicating an ascent. The distance between survey lines is also recorded is 0 to 100 feet in tenths of feet( not twelfths).
When gathering the data for the mapping of the cave, the mappers also make sketches of the cave walls and formations.They may also note any special information that should be included on the map, such as low ceiling heights, pools of water, unstable areas, etc. All of this is critical to forming a good map of the cave that can be used by others to safely navigate the cave.
All of the data, sketches, and other information are combined to form a map of the cave. A plan view is first developed by doing a line plot of the Stations using the measurements taken. An topography or elevation can also be added to the map from the clinometer readings. Then using the sketches and the plan view, a 3D map of the cave can be put together to give us a complete visual record of the cave.
This covers the concepts of cave mapping briefly. For more info contact the NSS and buy their books.
All of the above information combines to define the purpose of this project: to develop an application that will allow us to enter the data and automatically create the plan view of the cave. The ideal would be being able to scan in the sketches and apply them to a 3D wireframe of the cave as well.
