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Surveying Units and Terms

2 Oct 2019

Here is our list of units of measure, surveying terms, surveyors' slang and abbreviations, water descriptions, and trees.

If you don't see your favorite obscure units or terms, please let us know. We're happy to add to our list.

Units of Measure

• Acre - The (English) acre is a unit of area equal to 43,560 square feet, or 10 square chains, or 160 square poles. It derives from a plowing area that is 4 poles wide and a furlong (40 poles) long. A square mile is 640 acres. The Scottish acre is 1.27 English acres. The Irish acre is 1.6 English acres.
• Arpent - Unit of length and area used in France, Louisiana, and Canada. As a unit of length, approximately 191.8 feet (180 old French 'pied', or foot). The (square) arpent is a unit of area, approximately .845 acres, or 36,802 square feet.
• Chain - Unit of length usually understood to be Gunter's chain, but possibly variant by locale. A 100 foot chain is also sometimes used by American surveyors. See also Rathbone's chain. The name comes from the heavy metal chain of 100 links that was used by surveyors to measure property bounds.
• Colpa - Old Irish measure of land equal to that which can support a horse or cow for a year. Approximately an Irish acre of good land.
• Compass - One toise.
• Cuerda - Traditional unit of area in Puerto Rico. Equal to about .971 acres. Known as the "Spanish acre".
• Engineer's Chain - A 100 foot chain containing 100 links of one foot apiece.
• Furlong - Unit of length equal to 40 poles (220 yards). Its name derives from "furrow long", the length of a furrow that oxen can plow before they are rested and turned. See Gunter's chain.
• Ground - A unit of area equal to 2400 sq. ft., or 220 sq. meters, used in India.
• Gunter's Chain - Unit of length equal to 66 feet, or 4 poles. Developed by English polymath Edmund Gunter early in the 1600's, the standard measuring chain revolutionized surveying. Gunter's chain was 22 yards long, one tenth of a furlong, a common unit of length in the old days. An area one chain wide by ten chains long was exactly an acre. In 1595 Queen Elizabeth I had the mile redefined from the old Roman value of 5000 feet to 5280 feet in order for it to be an even number of furlongs. A mile is 80 chains.
• Hectare - Metric unit of area equal to 10,000 square meters, or 2.471 acres, or 107,639 square feet.
• Hide - A very old English unit of area, a hide was of variable size depending on locale and the quality of the land. It was the amount of land to support a family, and ranged from 60 to 180 acres. After the Norman conquest in 1066 it became standardized at around 120 acres.
• Hundred - An adminstrative area larger than a village and smaller than a county. In England it was 100 hides in size, and the term was used for early settlements in Virginia, Maryland, and Delaware.
• Labor - The labor is a unit of area used in Mexico and Texas. In Texas it equals 177.14 acres (or 1 million square varas).
• League (legua) - Unit of area used in the southwest U.S., equal to 25 labors, or 4428 acres (Texas), or 4439 acres (California). Also, a unit of length-- approximately three miles.
• Link - Unit of length equal to 1/100 chain (7.92 inches).
• Morgen - Unit of area equal to about .6309 acres. It was used in Germany, Holland and South Africa, and was derived from the German word Morgen ("morning"). It represented the amount of land that could be plowed in a morning.
• Out - An 'out' was ten chains. When counting out long lines, the chain carriers would put a stake at the end of a chain, move the chain and put a stake at the end, and so on until they ran "out" of ten stakes.
• Perch - See pole .
• Point - A point of the compass. There are four cardinal points (North, South, East, West), and 28 others yielding 32 points of 11.25 degrees each. A survey line's direction could be described as a compass point, as in "NNE" (north northeast). To improve precision, the points would be further subdivided into halves or quarters as necessary, for example, "NE by North, one quarter point North". In some areas, "and by" meant one half point, as in "NE and by North".
• Pole - Unit of length and area. Also known as a perch or rod. As a unit of length, equal to 16.5 feet. A mile is 320 poles. As a unit of area, equal to a square with sides one pole long. An acre is 160 square poles. It was common to see an area referred to as "87 acres, 112 poles", meaning 87 and 112/160 acres.
• Pueblo - A Spanish grant of less than 1000 acres.
• Rancho - A Spanish grant of more than 1000 acres.
• Rathbone's Chain - A measuring chain two poles, or 33 feet, in length.
• Rod - See pole
• Rood - Unit of area usually equal to 1/4 acre.
• Toise - Traditional French unit of length equal to 6 old French 'pieds' or feet, or 6.4 English feet.
• Vara - Unit of length (the "Spanish yard") used in the U.S. southwest. The vara is used throughout the Spanish speaking world and has values around 33 inches, depending on locale. The legal value in Texas was set to 33 1/3 inches early in the 1900's.
• Virgate - An old English unit of area, equal to one quarter of a hide. The amount of land needed to support a person.

Standard Surveying Terms

• A Frame - A measuring device built in the shape of an A. The distance between the legs is 6.6 feet (one tenth of a chain. To measure the acreage of a small square parcel, multiply the width and height in "A's" and move the decimal point three places to the left. For example, a square that is 6 A's wide and 4 A's tall is .024 acres.
• Aliquot - The description of fractional section ownership used in the U.S. public land states. A parcel is generally identified by its section, township, and range. The aliquot specifies its precise location within the section, for example, the northwest quarter of the southeast quarter.
• Auditor's map - was made by the County Surveyor at the request of the auditor for tax purposes. Many were made in the 1800's. Very little field work was done. The map was created bu the use of various documents, piecing together other surveys, a few rough measurements in the field, etc. Generally, not accurate.
• Azimuth - The number of degrees from north (or other reference direction) that a line runs, measured clockwise.
• Back sight - After measuring from point A to B, reading the heading from B back to A. Various factors can cause the headings to not be exactly the reverse of one another.
• Baseline - In the U.S. Public land surveying system, a surveyed east-west (i.e. latitudinal) reference line, often hundreds of miles in length, from which tiers of townships are are surveyed to the north and south. There are approximately two dozen baselines in the lower 48 states. See also meridian.
• Bearing - See azimuth. Bearings taken with a compass will be referenced to magnetic north unless otherwise noted.
• Benchmark - A survey mark made on a monument having a known location and elevation, serving as a reference point for surveying.
• Call - Any feature, landmark, or measurement called out in a survey. For example, "two white oaks next to the creek" is a call. So is "North 3 degrees East 120 poles".
• Chain carrier - An assistant to the surveyor, the chain carriers moved the surveying chain from one location to another under the direction of the surveyor. This was a position of some responsibility, and the chain carriers took an oath as "sworn chain carriers" that they would do their job properly.
• Chord - The straight line connecting the end points of an arc.
• Condition - See Conditional line.
• Conditional line - An agreed line between neighbors that has not been surveyed, or which has been surveyed but not yet granted.
• Corner - The beginning or end point of any survey line. The term corner does not imply the property was in any way square.
• Declination - The difference between magnetic north and geographic (true) north. Surveyors used a compass to determine the direction of survey lines. Compasses point to magnetic north, rather than true north. This declination error is measured in degrees, and can range from a few degrees to ten degrees or more. Surveyors may have been instructed to correct their surveys by a particular declination value. The value of declination at any point on the earth is constantly changing because the location of magnetic north is drifting. More information about historical values of declination is available.
• First station - See Point of Beginning
• Flag - A bright plastic ribbon tied to a lath stake. Used to mark points along a survey line.
• Gore - A thin triangular piece of land, the boundaries of which are defined by surveys of adjacent properties. Loosely, an overlap or gap between properties. See also strip.
• Landmark - A survey mark made on a 'permanent' feature of the land such as a tree, pile of stones, etc.
• Line Tree - Any tree that is on a property line, specifically one that is also a corner to another property.
• Merestone - A stone that marks a boundary. See monument.
• Meridian - In the U.S. public land surveying system, a surveyed north-south (i.e. longitudinal) reference line, often hundrends of miles in length, from which ranges are surveyed to the east and west. There are approximately two dozen meridians in the lower 48 states. See also baseline.
• Mete - In the context of surveying, a measure, i.e. the direction and distance of a property line.
• Metes and Bounds - An ancient surveying system that describes the perimeter of a parcel of land in terms of its bearings and distances and its relationship to natural features and adjacent parcels.
• Monument - A permanently placed survey marker such as a stone shaft sunk into the ground.
• Open line - A survey line, usually the final one, that is not measured and marked (blazed) by the surveyor but is instead calculated.
• Point of Beginning - The starting point of the survey
• Point of intersection - The point where two non-parallel lines intersect. More specifically, the point where two tangents to a curved line intersect.
• Plat - A drawing of a parcel of land. More specifically, the drawing created by the surveyor that shows the field work, with bearings, distances, etc.
• Plot plan - A diagram showing the proposed or existing use of a specific parcel of land.
• Plunge - 1) Inversion of a transit in order to make measurements that cancel errors in the transit, or to extend a line over an obstacle. 2) The angle a falling line makes with the horizontal.
• Protraction - in the rectangular survey system, the representation of a boundary or corner not run, marked, or fixed by the field survey as evidenced by the field notes. For example, a surveyed section might be protracted into lots by someone in the office.
• Quarter corner - in the public land surveying system, a point halfway between the corners of a section. A section can be divided into four equal quarters by connecting its quarter corner points. A section's quarter corners are identified by the section line they are located on (north, south, east, west).
• Range - In the U.S. public land surveying system, a north-south column of townships, identified as being east or west of a reference longitudinal meridian, for example, Range 3 West. See township.
• Riser - a tree branch or other similar object stuck in the ground and flagged to mark a survey point.
• Searles Spiral - A surveying technique used by railroad surveyors in the the late 1800s and early 1900s whereby they approximate a spiral by use of multiple curved segments.
• Section - In the U.S. public land surveying system, an area one mile square. See aliquot.
• Standard Corner - a corner that is on a standard parallel or base line
• Strip - A rectangular piece of land adjoining a parcel, created when a resurvey turns up a tiny bit larger than the original survey. The difference is accounted for by temperature or other effects on measuring chains. See also gore.
• Tangent line - A line that touches a circle at exactly one point and which makes a right angle with the circle's radius. For example, a circle that fills a square has four tangent points and the square's sides are tangent lines. An arc (curve) in a survey is part of a larger circle. One can construct tangent lines at the end points of the arc.
• Tie line - A survey line that connects a point to other surveyed lines.
• Tier - In the U.S. public land surveying system, an east-west row of townships identified as being north or south of a latitudinal baseline.
• Total station - A survey instrument that combines a theodolite and distance meter.
• Township - In the U.S. public land surveying system, an area six miles square, containing 36 sections. The townships are organized in tiers and ranges, identified with respect to a baseline and meridian. For example, Township 13 North Range 6 West describes a township's location.
• Traverse - 1) any line surveyed across a parcel, 2) a series of such lines connecting a number of points, often used as a base for triangulation.
• Trend - the bearing of a line along a falling course.
• Trocha - Spanish for 'path'. In the southeast U.S. it is used for a cut or cleared survey line.
• Witness Tree - Generally used in the U.S. public land states, this refers to the trees close to a section corner. The surveyor blazed them and noted their position relative to the corner in his notebook. Witness trees are used as evidence for the corner location.
• Zenith angle - An angle measured from a vertical reference. Zero degrees is a vertical line pointing up, 90 degrees is horizontal, and 180 degrees is straight down.

Surveyors' Slang

Surveying, like any profession, has its special terms and slang. Some are just humorous, some help distinguish similar sounds (e.g. eleven and seven), and some are just plain strange!

• Balls - Slang for numeric .00, as in 4-balls (4.00)
• Beep - Verb. To use a magnetic detector to look for iron pipe, etc.
• Blood - To slowly raise the levels rod in order that the instrument man can read the foot markings.
• Boot - To raise the levels rod some number of inches so as to be visible to the instrument man, e.g. "Boot 6!" means "raise it 6 inches."
• Blue topping - In road or grading work the surveyor sets stakes and paints their tops blue to represent the required elevation. Graders then work to just cover the blue tops of the stakes.
• Box - Data collector.
• Bug - To use a magnetic locator to search for an iron pipe.
• Bullseye - Zero degrees of inclination.
• Burn - See shoot
• Burn one - Measure from the one foot mark on the tape rather than from the end of the tape in order to increase the accuracy of the measurement.
• Bust - Closure error, i.e. the amount by which the survey fails to perfectly close.
• Cap - A metal or plastic cover on the end of a rebar or pipe, typically stamped or printed with the surveyor's license number or other identifier.
• Cut line - To clear vegetation for a line of sight between two survey control points.
• Double nickel - Slang for .55, as in 6-double nickel (6.55)
• Dummy or dummy-end - The base or zero end of a tape or chain, as in "hold dummy at the face of the curb."
• Dump - Download data from the data collector.
• EDM - Electromagnetic Distance Measurement device, the instrument used by modern surveyors that replaces the use of measurement chains. It determines distance by measuring the time it takes for laser light to reflect off a prism on top of a rod at the target location.
• Ginney - A wooden dowel 6-9 inches in length with a sharpened end. Set in the ground to mark survey points.
• Glass - The EDM prism.
• Gun - Originally, a transit, but potentially any measurement instrument in use, e.g. theodolite, EDM, or Total Station.
• Hours - Degrees
• Hub and Tack - A 2" by 2" stake that is set in the ground and that contains a nail ("tack") that precisely marks the point being set.
• Jigger - Transit (Australia and New Zealand)
• Legs - Tripod
• Pogo - Prism pole
• Pole - Approximate unit of measure (about 0.1 foot) used for stake out, e.g. "Move a pole to the left and drive that hub in"
• Punk - See railroad.
• Railroad - Slang for eleven, as in 42-railroad (42.11)
• Rodman - The person holding the rod with the EDM prism. This person is the modern version of a chain carrier or chain man.
• Shoot - Measure distance with an EDM
• Spike - Usually a 60 penny nail used to mark survey points in hard ground.
• Stob - In the southeast U.S., a wooden stake or post, but in modern surveying, a piece of rebar used to mark a property boundary.
• Tie - To locate something with the transit or other measuring device.
• Top - Slang for eleven. See railroad.
• Trip - Slang for triple digits, as in trip5 means 555, and 43trip7 means 43.777
• Turn - The rodman is told to stay in place while the gun or level is moved to a new location.
• Wave - To slowly move the levels rod back and forth in order to confirm that a measurement was made when the rod was truly vertical.
• Zero - Zero degrees, minutes, and seconds. A perfect zero.

Surveyors' Abbreviations

You might find the following abbreviations on a plat drawing. When a surveyor resurveys a tract they will "find" evidence of earlier surveys and will "set" new markers of their own. Thus F and S are common in abbreviations. The term "held" may be applied to markers found or set in the presence of other nearby pipes, rebar, etc. It means "this is the true corner".

• BRL - Building restriction line.
• BS - Back sight
• BSL - Building setback line.
• CIP - Capped iron pin
• CL - Center line
• Con Mon F - Concrete monument found
• CRB - Capped rebar
• EBL - East boundary line. Eastbound Lane.
• EIP - Existing iron pipe
• FD, FND - Found
• GPPM - General property parcel map
• IPF - Iron pipe/pin found
• IPPM - Individual property parcel map
• IPS - Iron pipe/pin set
• IRF - Iron rod found
• IRS - Iron rod set
• L.O.D. - Limit of Disturbance. The area to be cleared, graded, etc.
• LS - Licensed/Land Surveyor #
• MAG - New concrete nails are magnetic nails and are stamped with MAG on the head and are easier to find with metal detectors.
• MBS - Minimum building setback
• NBL - North boundary line. Northbound Lane.
• N/F - Now or formerly
• NIP - New iron pin
• NMS - No monument set
• NPP - Nail in power pole
• NTCFP - Nail on top of corner fence post
• NTFP - Nail on top of fence post
• NTS - Not to scale
• OHE - Overhead Electric
• PC - Point of curvature. The point at which a straight line begins to curve, i.e. the point of tangency to the curve. See PT.
• PCC - Point of compound curvature. The point where curves of different radii meet.
• PDE - Public drainage easement
• PI - Point of intersection
• PK - Point Known, PK nail
• PK nail - A concrete nail made by Parker Kaelon, stamped PK, that marks a survey point. See also hub and tack.
• PL - Property line
• POB - Point of beginning. The starting point of a survey.
• POL - Point on line. Used in situations where the end (final) point cannot be seen from the transit. Also used when the final point falls in water.
• PRC - Point of reverse curve. The point in an S-type compound curve where two curves of different polarity meet.
• PSDE - Private storm drain easement.
• PT - Point of tangency. The point at which a curve ends and straight survey line begins. See PC.
• R/C - Rod and cap, or rebar and cap
• RP - Radius point
• R/W - Right of way
• SBL - South boundary line. Southbound lane.
• SC - Standard corner
• SCM - Set concrete monument
• SMN - Set mag nail
• SR - Steel rebar
• SRS - Steel rod set (rebar or other steel)
• STE - Sight triangle easement
• UE - Utility easement
• WBL - West boundary line. Westbound lane.
• WC - Witness corner

Water Terms

• Arroyo - A small steep-walled (usually) dry watercourse with a flat floor. A gulch or gully. Chiefly in the U.S. southwest.
• Bank - Edge of a stream.
• Bed and banks - For property lines that cross a body of water, this term is used to explicitly refer to the bottom of the water.
• Bottom - Land along a river.
• Branch - Small stream.
• Brook - Small stream.
• Creek - Small stream.
• Drain - Small dry stream or gully.
• Draughts of - (pronounced drafts). See waters of.
• Drean - See drain.
• Ford - Shallow part of a stream or river where one could cross.
• Fork - Meeting point of two streams. "In the fork of" means between two branches.
• Gut - A narrow passage between hills. A stream in such a passage. A drain.
• Head - The source of a stream.
• Headwaters - The smallest streams that combine to make a larger stream.
• Kill - (Dutch) Creek.
• Lower - Toward the mouth of a stream. Further down along its course. Opposite of upper.
• Meander - "with the meanders of the stream" means the survey line follows the twists and turns of the stream.
• Mouth - The place where a stream enters another, larger stream.
• Narrows - Narrow part of a stream.
• River - Large stream.
• Run - Small stream.
• Shoal - Shallows.
• Spring - A pool or other source of water that feeds a stream.
• Swale - A low, generally marshy tract of land, either natural or manmade, e.g. for managing water runoff.
• Swamp - In the southeastern U.S., a stream, particularly one that has has swampy parts. A marsh.
• Thalweg - 1. An imaginary line connecting the lowest points of a valley. 2. The line connecting the lowest points of a stream's channel. 3. The surface midline of a channel.
• Thread of a creek. A figurative expression used to signify the center line of the main channel of a stream when the flow rate is low.
• Upper - Toward the head of a stream. Further up along its course. Opposite of lower.
• Vly - (Dutch) Swampy lowland.
• Waters ("watters") of - In the drainage of. On the branches of.

Trees

• Alder -
• Ash - has tough, straight-grained wood
• Aspen - a type of poplar
• Basswood - see linden
• Beech - smooth gray bark and small edible nuts
• Birch, (burch) -
• Black gum - see tupelo
• Blackjack - a type of small oak
• Black oak -
• Black walnut -
• Box elder -
• Box oak -
• Buckeye -
• Buffaloberry -
• Cedar -
• Cherry -
• Chestnut - American chestnut has been virtually destroyed by blight.
• Chestnut oak - has leaves resembling a chestnut
• Chittamwood - see Wooly Bumelia
• Cottonwood -
• Dogwood -
• Elder -
• Elm -
• Fir -
• Gambrel oak - see Oakbrush
• Gum - subtypes: black, sweet
• Hackberry - has cherry-like fruit
• Hawthorn -
• Hazel -
• Hemlock -
• Hickory, hiccory, hickry - has edible nuts and hard wood
• Hornbeam - has hard, heavy wood
• Ironwood - see hornbeam
• Juniper -
• Larch -
• Laurel -
• Lightwood - highly resinous pine, suitable for stakes
• Live oak -
• Lowerwood - transcription error for sourwood
• Magnolia
• Maple, (maypole)
• Mountain birch -
• Oak, (oake) - subtypes: black, box, chestnut, live, pin, post, red, scrub, shrub, Spanish, swamp white, white
• Oakbrush - scrub oak prevalent in southern Colorado west of the divide
• Pawpaw -
• Persimmon - has plum-like fruit
• Pine -
• Pin oak -
• Pohiccory - see hickory
• Ponderosa pine -
• Poplar, popular -
• Post oak - wood used for posts
• Red cedar -
• Red oak -
• Sapling, (saplin) - young tree
• Sassafras - bark used in medicines and beverages
• Scrub oak - usually found in dry, rocky soil
• Serviceberry - (sarvisberry)
• Sour gum - see tupelo
• Sourwood - sorrel tree
• Spanish oak -
• Spruce -
• Sugar tree - sugar maple
• Sumac - (shumac)
• Swamp white oak - heavy, hard wood used in shipbuilding, furniture, etc.
• Sweet gum - hard reddish brown wood used for furniture
• Sycamore -
• Tamarack - an American larch having reddish brown bark
• Tamarisk - small shrub found in the southwest
• Tupelo -
• Walnut - black
• White oak -
• Wooly Bumelia - leaves resemble a live oak with a fine fur-like fuzz on the underside.
• Yew -

Sources

You can find definitions for most of these units, terms, and words in any good unabridged dictionary. There are also books dealing with units of measure and surveying.

• Wm. Johnston, "For Good Measure".
• Untitled. Book listing State and Federal Laws relating to measures.
• Funk & Wagnall's Unabridged Dictionary, 1963
• Webster's Unabridged Dictionary, 1959
• Oxford English Dictionary
• Robert's Dictionnaire de la Langue Francaise, 1979
• Discussions with Mr. Galtjo Geertsema, Land Surveyor; Ms. Patricia Law Hatcher, lecturer on land records.
• "Land and Property Research in the U.S", Wade Hone, 1997
• Contributions from surveyors.