Resources

DOCUMENTING CHANGES
AT YOUR PETROGLYPH SITE:
HOW & WHAT TO OBSERVE

updated June 2022 by FSRA
Site Monitoring Form added Sept 2022

Taking detailed photos of panels and features, and existing graffiti, can be very helpful in observing and documenting changes in the future. The Nevada State Stewardship Program Coordinator suggests re-doing this every two years. Before a visit, carefully study the site record and previous monitoring forms.

A monitoring visit involves observing, and noting what you observe, at a rock art site. What is seen may be a change caused by natural processes and/or by human interaction. And importantly, an observation may be that a site has NOT changed; the fact that it is the same is also very important to record.

WHAT DO YOU SEE? OBSERVE CAREFULLY

A. Natural Changes: Look for change/no change at the site and note what you see including:

Exfoliation (flaking/peeling of stone, particularly granite) from heat/freezing over the seasons. The process is usually continuous.
Movement of significant features (loose rocks/boulders/fallen tree limbs that have moved or changed over the seasons. Has a significant tree died/blown over? etc.
Lichen grows in many of these areas and continues to spread over time, sometimes covering petroglyphs.

An observation of no change might be applied to a particular area of the site that is of special concern.

B. Human Interaction: Look for change/no change at the site and note what you see including:

Defacing of a particular glyph by scraping/scratching/painting, which results in adding to, obliterating, or modifying it.
Removal of a glyph by stone cutting or chiseling.
Adding to the site by making new marks: names, smiley faces, suns, etc.
Damage caused by pressure or heat from actions such as driving over a site, building campfires, etc.
Other interactions caused by touching such as doing rubbing, using chalk or chemicals, etc.

WHAT TO DO

A. Natural Changes:
Document change in writing and with photographs.

B. Human Interaction:

Observe carefully and look for any objects used to make the change (paint, spray can, nail, etc.). Also look for information related to who might have done this work: tire tracks, etc.
Play CSI and look over the site carefully before you walk around and undertake your own activity.
Is there anyone else around at the time you find a human disturbance? If so, photograph any vehicles, license plates and/or people from a distance. Do not identify your activity and do NOT confront any person you may encounter.

HOW TO RECORD WHAT YOU OBSERVE

A. Writing & Making Notes:

On your field copy of the site record note the exact location and type of activity. Written descriptions are very helpful. This information can be transferred to your monitoring report.

B. Photographing

Be sure to turn off the camera’s GPS so no location information is imbedded in photos! In photographing a damaged site do a landscape shot that provides context, a mid-range shot showing the panel or surrounding features, and a close up of the damage. In close up shots, be sure to add something that provides scale, a small ruler, a coin, etc. We often arrive when the sun is high in the sky and there are few shadows to delineate petroglyphs. You can enhance the definition of your photo by using some type of shade (small umbrella/large hat are handy) or wetting the feature with water. Do not use any other substance/chemical that may cause an interaction. Do not physically interact with the feature by chalking, taking a rubbing, or otherwise applying pressure. There is an interesting software program you may purchase called D Stretch. It was developed by mathematician Jon Harman. His website is www.dstretch.com. The program costs about $50. It may be downloaded to a computer or as an app to a cell phone. The computer version has a few more features. Both provide ways to create more definition which often help you to “see” features that are in flat light. While it works best with pictographs (painted images), it can be useful with some petroglyphs.

C. Sketching

Most site records contain many drawings/sketches. If you can sketch the changes onto your field copy of the site record or another sheet of paper, with an explanation, and then transfer that to your monitoring report, that is most helpful. We all have varying levels of skill and degrees of accuracy at this type of depiction, but try to at least outline what you are seeing.

D. GPS

Take a GPS coordinate or otherwise provide as precise a location as possible. In your monitoring report’s photo log, when relevant, add GPS coordinates to photo notations.

WHEN TO TAKE REMEDIAL ACTION: MAKING YOUR OWN CHANGES

Complete all investigation and documentation before undertaking remedial action.
If a concern at a site requires immediate notice to the US Forest Service and/or FSRA, call, text, or email the appropriate Forest Service archeologist or FSRA coordinator.
If there is graffiti or another ‘addition’ to the site, sometimes covering it with dirt or a rock will decrease its visibility and removes its example for others (newly scratched/peck rock especially shows up and gets attention). With a campfire ring, the ashes can be dispersed and the area covered with rocks to discourage future use. A log across a site feature can be removed, etc. If someone has driven across a site, if possible, position a log or rocks or other such object in a way that discourages others from doing the same. Remove any rock cairns.
If there is lichen or anther natural process interfering with glyph, please leave as it is and report it. The Forest Service has its own experts if any action needs to be taken.

DOWNLOAD THE FSRA ‘SITE MONITORING FORM’ AS A PDF FILE TO RECORD & SUBMIT YOUR OBSERVATIONS…

KNOW YOUR PACE FOR MONITORING
PETROGLYPH SITES

updated October 2020 by FSRA

Knowing your “pace” allows you to use walking to measure approximate distances at a rock art site. This can help you, for example, find a petroglyph panel, artifact, or feature in relation to a site’s datum (while also using your compass). In such a case, you would know from the site record the distance in meters the object is from the datum and at what compass bearing it is.

To know what your pace is:
Step 1: Measure out 30 meters in a straight line.
Step 2: As naturally as possible, walk from one end to the other ten times, counting your number of steps. (You can write down the number of steps for each of the ten 30 meter “walks” and then add them up at the end.)
Step 3: Divide 300 (the total number of meters walked) by the total number of steps to get the metric distance for each step.

A “pace” is actually defined as two steps, so double the answer from Step 3 to get the metric distance for one of your paces. (Or just use individual “steps.”)

Example using “steps:”

Lets say that walking the 30 meter distance 10 times (ie 300 meters) took 447 steps. 447 (total steps) divided by 300 (total meters) = 1.49 steps per meter (in this case, you can round this off to 1 1⁄2 steps if you want)
If you want to find a petroglyph panel the site record tells you is 56 meters and 190 degrees [South] from the datum, with your back close to the datum and your compass in hand (adjusted for declination), as you face 190 degrees, you walk about 84 “steps” (1 1⁄2 steps x 56 meters = 84) to the panel.

Of course, you may not be able to walk a straight line on even ground, so you have to allow for the terrain (and don’t walk over petroglyphs). In other words, it may take more steps than you projected. (Knowing how to navigate with a compass can help if you have to walk around obstacles.

BEING SAFE AROUND RATTLESNAKES

by Bill Drake – June 2014

Like other members of FSRA, over the years I have spent hundreds of hours in the wilderness. The first time I saw a rattlesnake, which was at a petroglyph site in the high Sierra, I realized that I needed to know more about them in order to feel completely comfortable at remote settings. For the next year I did a considerable amount of research on the reptiles and then wrote an article about them for Sierra Heritage magazine as well as a handout for Forest Service archaeologists. So others will feel more at ease hiking in areas snakes inhabit, this article will share some of what I learned.

The Western Rattlesnake inhabits a large portion of the western U.S., including most of California. Its main subspecies in northern California is the Western Pacific Rattlesnake. In some parts of the Sierra, since they hibernate for the winter, they are most active in the spring when they come out of hibernation. The next most active time in the Sierra range is usually in the fall when they are seeking more food to build up fat for the next period of reclusion.

Where they are found has a lot to do with their body temperature. Temperature permitting, they can be found any time, day or night. During summer they tend to be especially active at night. During the day, a snake may be in the shade of a bush or rock, waiting for an unsuspecting rabbit, lizard, or other food source. On hot days they may rest in a mammal’s hole or a shady spot. If the ground is cool, and the air temperature at ground level is between about 55 and 75 degrees, they may bask in the sun, sheltered from a cool breeze. Western Rattlesnakes like shady bushes and rocky areas, such as ledges and outcroppings.

The most reassuring thing to know is that in our area, as a general rule, it is rare to see a rattlesnake and very rare to be bitten by one. Rattlesnakes almost always avoid contact with people by lying still or retreating. I have heard of one or two aggressive rattlesnakes in our region but they were rare exceptions. The only time a rattlesnake tried to chase after me was after I accidentally ran over it with my car on a dirt road near rock art sites in Bishop, California, and I stopped to see how it was doing. If threatened, they often coil and shake their rattles to warn intruders, although you can be bitten without hearing such a warning. And while snake bites can be very painful and severely damage your body tissue, they are almost never fatal. A California Dept. of Fish & Game website states that no venom is injected in about 25% of rattlesnake bites. The Centers for Disease Control estimates that only 5 people die from bites by all types of venomous snakes in the United States per year. Read more at California Dept. of Fish & Game
‘Be Rattlesnake Safe’ webpage.

Many snake bites relate to bad behavior on the part of humans. In one Los Angeles County study, three-quarters of rattlesnake bites were in young adult males who had been drinking and teasing snakes. A poison information specialist at U.C. Davis Medical Center has concluded, “The easiest way to get bitten by a rattlesnake is by being an idiot!”

Keep in mind that rattlesnakes, at top speed, can only crawl about as fast as a human being can walk. A rattlesnake can bite from any position, lying flat or coiled. They can also coil and strike in an instant. From a coiled position, however, they rarely strike more than one-half to three-quarters of their length and generally do not strike higher than one-and-one-half feet above the surface they are on.

Photograph taken at the Wabena Point petroglyph site!

Aside from idiotic behavior, bites most often occur when a person surprises a rattlesnake, causing it to react. This often happens when the person puts a hand or foot in an area they cannot see. This can include, for example, stepping over a log or large rock without looking on the other side, or putting a hand on a ledge, or inside a woodpile at home, that is not or can not be inspected beforehand. Hikers walking past brush where a snake is resting or hiding can also startle a snake.

While snakes can feel ground vibrations, they do not appear to respond to sound waves. Singing operas while hiking may scare other hikers away but will not affect snakes.

If you hear a rattler rattling, stand still until you can determine where it is. Move slowly out of the snake’s range then get quickly away from the immediate area once you are sure there is not another rattler in the direction you will be going.

If you are bitten by a venomous snake, a companion should treat you for shock. Try to keep the affected area immobilized and below heart level. If a foot is involved, minimize its motion as much as possible. Get medical help as soon as you can. Call a hospital in advance so they can prepare for your visit. They will give you an anti-venom to counteract the poison. Walking or other activity by the victim increases the metabolic rate, which can cause the venom to spread and be absorbed much quicker. Excessive warmth also has this effect. If the victim must walk out, he/she should walk slowly and rest every five minutes.

If you are more than a couple of hours from a hospital, you might use an extraction kit (Sawyer’s Extractor vacuum pump kit is recommended), which may suck out up to 30% of the venom if used right away. The longer one waits to use the kit the less effective it will be. If you are less than a couple of hours from a hospital, forget extraction and get there as soon as you can.

The old suggestions to use a constriction band or tourniquet, to use a razor knife to make an incision at or near the bite, to suck out the poison with your mouth, to put ice on the wound, or to give alcohol or stimulants to the victim, are all very bad ideas. Do not give the victim aspirin which can make it harder for the blood to coagulate.

When hiking in the wilderness, it is recommended that you have one or more companions. You should also have a plan of action in the case of snakebite or another emergency. You should know where the nearest emergency facility is and what phone number to call for help. If you are several hours from medical help, carry a Sawyer’s Extractor Pump kit and know how to use it.

Remember that rattlesnakes will try to avoid or warn you, their striking distance is not very long, and that you can easily out pace them. Be alert when you are hiking and always be aware of where you put your feet and hands. An often quoted rule of advice is that “the only dangerous rattlesnake is the one you don’t see.”

SITE MONITORING COMPASS PROCEDURES

updated June 2022 by FSRA

A base plate compass, with rotating housing, is recommended, with or without a mirror (Silva & Suunito are good brands; $20-$60). A compass that can be adjusted to automatically allow for declination is preferred. Keep the compass level when in use. Iron or steel objects can deflect the compass needle if too close. Do not lay a compass where temperature can be extreme, such as on a hot surface in the sun.

SOME DEFINITIONS:

“Orienting Compass”. . . designed for easy navigation using map and compass; has a turnable housing mounted on a base plate. (Some orienting compasses have a clinometer to measure slope angles.)
“Base Plate” . . . the rectangular plate of an orienting compass which has the compass housing on it.
“Compass Housing” . . . the compass part that contains the needle; on an “orienting compass” it is turnable.
“Orienting Arrow”. . . an arrow marking or parallel lines on an “orienting compass’” housing used to “set” the compass.
“Compass Site Line”. . . this shows the direction of travel or the direction for the bearing of interest .
“Bearing”. . . when the term is used for compass orienting it refers to a direction stated in compass degrees.
To “Take a Bearing”. . . to determine the direction in compass degrees from one object (usually you) to another.
“Back Bearing”. . . the opposite direction of a bearing; a useful reading to take in certain situations.
“Magnetic Declination” . . . the angle between Magnetic North & True North.

SIGHTING WITH A MIRROR COMPASS

Hold it at eye level, pointed away from you, with the mirror at about 45 deg.; sight while using mirror.

SIGHTING WITH A COMPASS WITHOUT A MIRROR – or when using a mirror compass without the mirror for a less accurate reading
Hold it at waist or abdomen, a few inches away from your body (away from a metal belt buckle, etc); perpendicular to your body, pointed away from you; cover (if any) wide open so whole compass is flat.

ADJUSTING FOR MAGNETIC DECLINATION (“N” = North) – for a location’s declination angle: www.magnetic-declination.com
The True N Pole is located geographically, while the Magnetic N Pole (where compass needles point) is where the earth’s magnetic lines of force come together. Magnetic N moves slightly year to year. Maps and directions are usually based on True N, which is fixed. You have to adjust the compass for the declination angle (the angle between True N and Magnetic N) to get readings based on True N. Currently (2022) the declination for Nevada County, California is about 13 1/4 deg. E (you can just use 13 deg.). You can adjust for this manually for each reading or use a compass that can be set to automatically adjust. In the W. US ADD the degrees (rotate compass housing CCW 13 deg.), in the E. US SUBTRACT the degrees (rotate compass housing CW 13 deg.) (NOTE: If you put a compass bearing in a monitoring report, mention what declination you are using.)

TO FOLLOW A KNOWN BEARING FROM THE DATUM TO A PANEL, FEATURE, OR ARTIFACT

For example, to find a petroglyph panel on the site map at 190 deg. from the datum. As well as needing the bearing or degree to follow, you will need to know the distance so you can pace it off as you follow the bearing. (Unfortunately, older site maps will be based on an old declination, throwing you off some.)

WITH A COMPASS THAT IS SET TO ADJUST FOR DECLINATION AUTOMATICALLY:

Stand next to and in front of the datum with your back to it and face the general direction of interest
Rotate the compass housing to line up the desired degrees with the compass sight line
Move your body and compass together to line up the N needle with the orienting arrow; your sight line now points in the direction you want to go.

WITH COMPASS THAT YOU HAVE TO ADJUST FOR DECLINATION WITH EACH READING:

Stand next to and in front of the datum with your back to it and face the general direction of interest
Rotate the compass housing to line up the desired degrees with the compass sight line
Move body and compass together to line the N needle up with 13 deg. more than orienting arrow’s direction (adding 13 deg. to Magnetic N); your sight line now points in the direction to go

TAKE A BEARING FROM THE DATUM TO A PANEL, FEATURE, OR ARTIFACT YOU CAN SEE

This should only be necessary if the item is not in the site record, in which case you record degrees and distance from the datum.

WITH A COMPASS THAT IS SET TO ADJUST FOR DECLINATION AUTOMATICALLY:

Stand next to and in front of the datum with your back to it, and line up the compass sight line with the object
Line up the orienting arrow with N on the needle; this gives you the bearing at your sight line

WITH A COMPASS THAT YOU HAVE TO ADJUST FOR DECLINATION FOR EACH READING:

Stand next to & in front of datum with your back to it, and line up compass sight line with the object
Rotate the housing to line up the N needle so it points to 13 degrees more than the direction the orienting arrow points (adding 13 deg. to Magnetic N) (add the 13 deg by watching degree “ring” on the housing OR red degree marks to right of orienting arrow); this gives you the bearing at your sight line.

(If you cannot see the datum from the object, you can use a GPS to find the approximate distance and bearing from the datum. Note the reliance on a GPS for these things in your report. Another option, if it would be acceptable to the USFS, may be to establish a new datum that is visible from the object and from which you can get a bearing and distance to the object.)

TAKE A BACK BEARING FROM A PANEL, FEATURE, OR ARTIFACT TO THE DATUM

This procedure is useful if you find a panel, feature, or artifact that is not in the site record, and, while standing directly in front of it, want to document its location as would be determined from the datum, which you have to be able to see. You would still need to find (pace off) the distance between it and the datum for your report.

WITH A COMPASS THAT IS SET TO ADJUST FOR DECLINATION AUTOMATICALLY:

Stand next to and in front of the object with your back to it, facing the datum, and aim your compass at the datum
Rotate the housing to up the orienting arrow with the S half of the compass needle
Read the degrees at the sight line; this would be the bearing from the datum to the object

WITH A COMPASS THAT YOU HAVE TO ADJUST FOR DECLINATION FOR EACH READING:

Stand directly in front of the object with your back to it, facing the datum, and aim your compass at the datum
Rotate the housing to line up the S half of the compass needle with the orienting arrow plus (add) 13 deg. (add 13 deg. by watching degree “ring” on housing OR red degree marks to right of orienting arrow)
Read the degrees at the sight line; this would be the bearing from the datum to the object ALTERNATIVE APPROACH Take a bearing on the datum (allowing for declination) and add or subtract 180 deg., whichever keeps you below 360 deg. total – that is your back reading.
If you cannot see the datum from the object, you can use a GPS to find approximate distance and bearing from the datum. Note the reliance on a GPS for these things in your report. Another option, if it would be acceptable to the USFS, may be to establish a new datum that is visible from the object and from which you can get a bearing and distance to the object.

OLDER SITE RECORDS WILL HAVE AN OLDER DECLINATION

As noted, the declination changes a little each year. Currently it is a little over 13 deg. for Nevada County. Site records from the 1990s used a declination closer to 17 deg. (If you are working with a topo map, it should note the declination used at the bottom. Unfortunately the declination for site records is not always noted.) You might find that you are searching for an old report’s feature by following a compass bearing and pacing the proper distance from the datum, and have gone the right distance but are not at the feature due to a change in the declination being used. In this case, move toward your left (if your back is toward the datum) a few degrees to see if you can locate it. This puts you more in line with the old declination that was used.

Good book: Wilderness Navigation, Bob and Mike Burns, 3rd ed. 2015 (See separate FSRA handout “Site Monitoring with a Recreational Grade GPS.” In some cases, it helps to use both a compass and a GPS.)

SITE MONITORING WITH
A RECREATIONAL GRADE GPS

by Bill Drake – updated July 2021

Note: The Forest Service’s highly accurate Trimble professional GPS is only occasionally available for public use.

ACCURACY

The first thing to keep in mind when using your own “recreational grade” (ie, non-professional) GPS is that its readings are approximate. Garmin notes on their website, “Garmin® GPS receivers are accurate to within 15 meters (49 feet) 95% of the time. Generally, users will see accuracy within 5 to 10 meters (16 to 33 feet) under normal conditions.” (Some GPSs have a “waypoint averaging” feature allowing for greater accuracy.)They also note, “Certain atmospheric factors and other sources (tall buildings, densely populated areas, etc.) of error can affect the accuracy of GPS receivers.”

You GPS should have a “satellite” page you can refer to, which allows you to see what satellites you are getting input from, what the strength of their input is, and the estimated accuracy at that moment. If the device is not accurate enough, you can watch that page for awhile to see if it improves as satellite input improves. For example, over a few moments, the accuracy may go from within “18 feet” to within “9 feet” (or less) at which point you might record your position or take some other action.

If you are using a USGS topo map (or a map from Garmin or another GPS map distributer), keep in mind that it can be inaccurate to a small degree as well.

MAP DATUM

From Wilderness Navigation, Burns & Burns: “A datum is a point of reference used by mapmakers, surveyors, and GPS device manufacturers, upon which to base position coordinates.” From Basic Illustrated: Using GPS, Grubbs: “A datum is a model of the earth’s surface based on a surveyed network of physical points.” From The GPS Handbook, Egbert & King: “Early datums assumed the earth was a perfect sphere, but modern satellite measurements have produced much more accurate datums.”

If your GPS datum does not match the datum for the map that is being used, your coordinates can be a mile or more off. Old USGS maps and old USFS site records relied on the NAD 27 CONUS datum (North American Datum of 1927) but that datum has generally been replaced by the more accurate NAD 83 (North American Datum of 1983). WGS 84 (World Geodetic System of 1984) is often used as a default datum by GPS systems. Its coordinates are usually within a meter or two of NAD 83 in the continental U.S. The same coordinates for NAD 83 (/WGS 84) and NAD 27 can have a difference of as much as 200 meters. A USGS map’s information section will tell what datum is relevant. Unfortunately, many sources on the internet give you coordinates but not the datum.

For the USFS be sure and set your GPS’s datum for NAD 83 and note your use of that datum when you put coordinates in your site report. Keep in mind that old USFS site records (usually 1990s and earlier; sometimes even later than that) will have used NAD 27. Your site record may not tell you which was relied on.

Once when I adopted a new site to monitor, in my first monitoring report I noted that the site record’s coordinates for the site datum were 100-200 meters off. What I found out later was that the old report was relying on NAD 27 and I was using the current USFS datum of NAD 83.

Note: You can use your GPS or Garmin computer map program (BaseCamp) to convert coordinates made with one map datum to coordinates for another datum by changing the datum used by the GPS or map program.

Reference: www.maptools.com/tutorials/map_datum

Different systems are used to assign coordinates to locations on the earth’s surface. Latitude/Longitude is based on degrees, minutes (fractions of a degree), and seconds (fractions of a minute). The UTM system divides the earth into zones and uses meters as its unit of measurement. The USFS uses UTMs for coordinates and all measurements are done with the metric system (ie, meters, centimeters).

USING A GPS TO MARK A LOCATION

If you have a GPS, you will know, or quickly learn, how to “mark” a location or “waypoint,” and access your collection of waypoints on the GPS. If you find a petroglyph panel, feature, or artifact that is not in your site report, you will “mark” it’s location on your GPS so you can add its coordinates to your report, noting that you used a recreational GPS to get the information. You can also “mark” all the site’s features, panels, etc., as you find them the first time so you can easily locate them on future visits. (NOTE: Remember, site locations are kept confidential and any coordinates on the GPS that locate a site should be deleted when not needed. Be very careful with site coordinates.)

INPUT A COORDINATE INTO YOUR GPS SO YOU CAN FIND ITS LOCATION

To use a GPS to find a site you have the coordinates for (from the site record), you need to enter them into the GPS. One way to do this is to “mark” or make a new “waypoint,” and then switch to the editing field for the waypoint and change its coordinates to the site’s coordinates. Then you can use the GPS’ “go to” feature to find the location. With Garmin you can also put the coordinates in BaseCamp and transfer them from there to the GPS. (See “NOTE” in previous entry.)

MEASURING DISTANCE WITH YOUR GPS (AND DETERMINING APPROXIMATE COMPASS DIRECTION)

You can use the GPS to measure distance, for example from the site datum to a new petroglyph panel you found, but keep in mind that the results will be approximate and may be less accurate than pacing or walking the distance. To measure distance, in this example, stand at the datum and mark the waypoint or location on the GPS, then stand at the panel and bring up the waypoint for the datum and your GPS should tell you how far away it is. Most likely, the closer it is, the less accurate the reading will be. With my satellite page noting an accuracy of within about 2 1⁄2 meters, I did three tests over a 30 meter distance. Test 1 yielded 28.95 meters, test 2 – 30.17 meters; and test 3 – 28.04 meters. That is not too bad. Theoretically, if each of your readings are as much as, for example, 2 1⁄2 meters off, with the GPS reading both where the datum is and where the panel is, you could be as much as 5 meters off altogether. If you use your GPS as opposed to pacing for distance measurement, be sure and note that in your report. (The GPS also gives you the approximate direction to the object, which you can record, but an orienting compass would be more accurate.)

ADDITIONAL NOTES
“Go To” feature vs following a “track” – A challenge with telling your GPS to “go to” a location for which it has

coordinates is that as satellite input fluctuates, the direction you are told to go fluctuates some, making this type of navigation challenging, but it works. When I am following a previously recorded “track” to a location I have been to, while my location shown on the GPS’s track line are a little approximate due to satellite fluctuation, the results are pretty good. (A GPS can help in telling you distance and direction in relation to a coordinate you are trying to reach.)

Compass – if your GPS has a compass, that can be used to navigate to a location, but again, the bearing will fluctuate some as satellite input fluctuates. Be sure the compass is “calibrated.”

Map – It is invaluable to have a map in your GPS that shows you your location and surroundings.
Extra Batteries – Be sure and have these on hand.
An “Orienting Compass” – A good compass can be used instead of, or in addition to, a GPS. In some cases this will result in more accurate work. (See separate FSRA handout “Site Monitoring Compass Procedures.”)
Good Books on GPS Use – Wilderness GPS, Bob Burns & Mike Burns c2013, 2nd ed. (150pp); Basic Illustrated:

Using GPS (“A Falcon Guide”), Bruce Grubbs c2014, 3rd ed. (85pp)