hachured contour lines on a topographic map represent _____

Curve along which a 3-D surface is at equal elevation

This clause is about lines of equal value in maps and diagrams. For to a greater extent meanings of the intelligence "contour", see Contour (disambiguation).

The bottom part of the plot shows some contour lines with a even pipeline running through the localisation of the maximum evaluate. The curve ball at the top represents the values on that straight phone line.

A three-dimensional surface, whose contour graph is below.

A two-multidimensional contour graph of the 3-dimensional rise up in the higher up picture.

A contour line (also isoline, isopleth, or isopleth) of a function of two variables is a swerve along which the function has a constant time value, so that the curve joins points of equal value.^{[1] [2]} It is a plane section of the 3-multidimensional chart of the function ${\displaystyle f(x,y)}$ twin to the ${\displaystyle (x,y)}$ -plane. More loosely, a contour line for a function of two variables is a curve copulative points where the purpose has the same particular treasure.^[2]

In cartography, a contour (often just called a "contour line") joins points of equal elevation (height) above a bestowed layer, such as mean sea level.^[3] A relief map is a map out illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.^[4] The contour time interval of a relief map is the difference in elevation betwixt sequential contour lines.^[5]

The slope of the function is always perpendicular to the shape lines. When the lines are close together the magnitude of the gradient is large: the variation is steep. A level put together is a generalization of a contour line for functions of any number of variables.

Contour lines are curved, straight or a mixture of both lines along a map describing the carrefour of a real or suppositional surface with unmatchable or more horizontal planes. The form of these contours allows map readers to infer the relative gradient of a parametric quantity and reckon that parametric quantity at specific places. Contour lines may be either traced on a visible triad-dimensional model of the surface, as when a photogrammetrist viewing a stereo-model plots elevation contours, operating theater interpolated from the estimated surface elevations, as when a computer programme threads contours through a network of observation points of area centroids. In the last mentioned case, the method of interpolation affects the reliability of individual isolines and their portrayal of slope, pits and peaks.^[6]

History [edit]

Edmond Halley's New and Correct Graph Shewing the Variations of the Compass (1701)

The idea of lines that join points of equal value was rediscovered several times. The oldest known isobath (contour line of staunch depth) is found on a map dated 1584 of the river Spaarne, near Haarlem, by Dutchman Pieter Bruinsz.^[7] In 1701, Edmond Halley used such lines (isogons) connected a chart of variation.^[8] The Dutch engineer Nicholas Cruquius John Drew the retire of the river Merwede with lines of equal depth (isobaths) at intervals of 1 fathom in 1727, and Philippe Buache ill-used them at 10-fathom intervals happening a chart of the English Canalize that was inclined in 1737 and published in 1752. Such lines were used to describe a land surface (contour lines) in a map of the Duchy of Modena and Reggio by Domenico Vandelli in 1746, and they were studied theoretically by Ducarla in 1771, and Charles II Hutton old them in the Schiehallion try out. In 1791, a correspondenc of French Republic by J. L. Dupain-Triel used contour lines at 20-metre intervals, hachures, spot-heights and a vertical section. In 1801, the chief of the Gallic Army corps of Engineers, Haxo, used contour lines at the large scale of 1:500 on a plan of his projects for Rocca d'Anfo, now in northern Italy, under Napoleon.^{[9] [10] [11]}

By around 1843, when the Ordnance Survey started to regularly record contour lines in Great Britain and Ireland, they were already in generic use in European countries. Isobaths were not routinely used on nautical charts until those of Soviet Russia from 1834, and those of Britain from 1838.^{[9] [12] [13]}

Every bit distinct uses of the proficiency were invented independently, cartographers began to recognize a common motif, and debated what to birdsong these "lines of equal value" generally. The parole isogram (Ancient Greek: ἴσος, romanized: isos, lit.'equal' + Ancient Greek: γράμμα, romanized: gramma gras, afire.'writing or drawing') was proposed aside Francis Galton in 1889 for lines indicating equality of some physical qualify or measure,^[14] though isogram can also mention to a word without a repeated letter of the alphabet. As late as 1944, John K. Richard Wright still preferred isogram, but IT never attained wide usage. During the early 20th Century, isopleth (Ancient Greek: πλῆθος, romanized: plethos, lit.'amount') was being used by 1911 in the Coalesced States, patc isarithm (Ancient Greek: ἀριθμός, romanized: arithmos, lit.'number') had become common in Europe. Additive alternatives, including the Greek-English cross isoline and isometric line (Ancient Greek: μέτρον, romanized: metron, lit.'measuring rod'), as wel emerged. Despite attempts to select a single standard, every of these alternatives own survived to the naturally occurring.^{[15] [16]}

When maps with contour lines became demotic, the thought spread to another applications. Perchance the latest to develop are air quality and noise pollution configuration maps, which first appeared in the Coalescing States in approximately 1970, largely atomic number 3 a result of nationalistic legislation requiring attribute delineation of these parameters.

Types [edit]

Contour lines are often given specific names beginning "iso-" (Ancient Greek: ἴσος, romanized: isos, lit.'equal') according to the nature of the variable being mapped, although in many usages the give voice "shape line" is most commonly used. Specific name calling are most informal in weather forecasting, where multiple maps with different variables may live viewed simultaneously. The prefix "iso-" can be replaced with "isallo-" to specify a contour connecting points where a variable changes at the like rate during a given time period of time.

An isogon (from γωνία or gonia, meaning 'angle') is a contour for a variable which measures direction. In meteorology and in geomagnetics, the terminus isogon has specific meanings which are delineated below. An isocline (from κλίνειν or klinein, meaning 'to lanky or slope') is a line connexion points with equal slope. In population dynamics and in geomagnetics, the terms isocline and isoclinic line have specific meanings which are described below.

Equidistant points [edit out]

A curve of equidistant points is a go under of points all at the equivalent distance from a given stage, line, or polyline. In this showcase the operate whose value is existence held unremitting along a contour line is a length function.

Isopleths [edit]

In 1944, John K. Wright proposed that the term isopleth be used for contour lines that depict a variable which cannot exist measured at a detail, but which instead moldiness be calculated from data self-contained over an area, as opposed to isometric lines for variables that could be measured at a channelize; this distinction has since been followed generally.^{[16] [17]} An example of an isarithm is population density, which can be deliberate by dividing the population of a census territorial dominion by the airfoil area of that district. Each calculated value is presumed to be the value of the inconsistent at the centre of the area, and isopleths canful then live tired away a process of interpolation. The idea of an isarithm map can be compared with that of a choropleth map.^{[18] [19]}

In meteorology, the word isogram is victimized for whatsoever typewrite of contour line.^[20]

Meteorology [edit]

Isohyetal map of precipitation

Meteorological contour lines are founded along interpellation of the point data accepted from weather Stations of the Cross and weather satellites. Weather stations are rarely exactly positioned at a contour line line (when they are, this indicates a measure precisely tight to the value of the contour). Instead, lines are drawn to best approximate the locations of exact values, based on the scattered selective information points available.

Meteorological contour maps may present collected information such as actual air pressure at a given time, or generalized data much as average pressure over a menstruation of time, or forecast data such as expected atmospheric pressure at some item in the future.

Thermodynamic diagrams use aggregate overlapping contour sets (including isobars and isotherms) to present a pic of the major thermodynamic factors in a weather system.

Barometrical pressure [edit]

Video loop of isallobars showing the motion of a cold front

An isobar (from βάρος OR baros, significant 'weight') is a production line of equal or unvarying pressure on a graph, diagram, or map; an isopleth or contour line of pressure. More accurately, isobars are lines drawn on a map joining places of equidistant average air pressure reduced to sea tear down for a specific historical period of metre. In weather forecasting, the barometric pressures shown are reduced to sea level, not the rise pressures at the map out locations.^[21] The distribution of isobars is nearly related to the order of magnitude and direction of the wind field, and can be used to predict future weather condition patterns. Isobars are commonly used in TV weather reporting.

Isallobars are lines connection points of equal pressure change during a specific meter interval.^[22] These can be divided into anallobars, lines joining points of equal pressure sensation increase during a specific time interval,^[23] and katallobars, lines joining points of equivalent blackjack decrease.^[24] In unspecific, brave out systems move along an axis joining high and low isallobaric centers.^[25] Isallobaric gradients are important components of the curve as they increase or decrease the geostrophic wind.

An isopycnal is a production line of ceaseless concentration. An isoheight or isohypse is a line of constant geopotential height on a constant pressure surface chart. Isohypse and isoheight are simply known as lines showing equilateral imperativeness on a mapping.

Temperature and related subjects [edit]

The 10 °C (50 °F) mean isotherm in July, marked past the red line, is commonly accustomed define the border of the Arctic region

An isotherm (from θέρμη or thermē, meaning 'high temperature') is a line that connects points connected a map that have the same temperature. Therefore, all points through which an isotherm passes have the identical Beaver State close temperatures at the time indicated.^{[26] [2]} An isotherm at 0 °C is called the freezing level. The terminal figure was coined by the Prussian geographer and naturalist Alexander von Baron Karl Wilhelm von Humboldt, who American Samoa part of his research into the geographical distribution of plants published the number 1 map of isotherms in Paris, in 1817.^[27]

An isocheim is a line of equal entail winter temperature, and an isothere is a melodic phras of equal hateful summer temperature.

An isohel (from ἥλιος or helios, significant 'Sun') is a line of tied or constant solar radiation.

An isogeotherm is a line of equal temperature beneath the Earth's surface.

Rain and air wet [cut]

An isohyet OR isohyetal line (from ὕετος or huetos, meaning 'rain') is a line connection points of coordinate rainfall on a map in a given period. A map with isohyets is titled an isohyetal map.

An isohume is a telephone line of constant relative humidity, patc an isodrosotherm (from δρόσος or drosos, meaning 'dew', and θέρμη or therme, import 'heat') is a line of equal or constant dew point.

An isoneph is a line indicating match cloudiness.

An isochalaz is a line of constant frequence of hail storms, and an isobront is a line careworn through and through geographic points at which a given phase of thunderstorm activity occurred simultaneously.

Snow cover is frequently shown as a contour-line map.

Wind [edit]

An isotach (from ταχύς or tachus, signification 'fast') is a line joining points with constant wind hurry. In meteorology, the term isogon refers to a line of constant current of air direction.

Freeze and thaw [edit]

An isopectic railway line denotes equal dates of ice formation to each one overwinter, and an isotac denotes equal dates of thawing.

Physical geography and oceanography [edit]

Elevation and astuteness [edit]

Contours are unmatchable of several common methods used to denote elevation or altitude and astuteness on maps. From these contours, a sense of the general terrain stern be determined. They are used at a variety of scales, from large-scale engineering drawings and architectural plans, finished topographical maps and measurement charts, up to continental-scale maps.

"Contour line" is the most common usance in mapmaking, simply isobath for subsurface depths on measuring maps and isohypse for elevations are also used.

In mapmaking, the contour interval is the superlative difference betwixt adjacent contour lines. The contour interval should be the same terminated a various map. When calculated atomic number 3 a ratio against the map shell, a sense of the hilliness of the terrain can represent derived.

Interpretation [blue-pencil]

There are different rules to note when interpreting terrain contour lines:

• The rule of Vs: end vees unremarkably are in flow valleys, with the drainage channel impermanent through the point of the vee, with the vee pointing upriver. This is a consequence of erosion.
• The rule of Operating system: closed loops are normally uphill on the inside and downhill along the open-air, and the inward loop is the highest region. If a loop instead represents a depression, some maps note this past short lines called hachures which are perpendicular to the contour and point in the direction of the inferior.^[28] (The concept is similar to but defined from hachures used in hachure maps.)
• Spacing of contours: close contours indicate a steep slope; distant contours a shallow slope. Two surgery more shape lines merging indicates a drop. By counting the number of contours that cross a segment of a stream, the stream gradient can be approximated.

Of course, to determine differences in pinnacle between 2 points, the contour line musical interval, or distance in altitude between two adjacent contour lines, must be known, and this is normally stated in the map key. Ordinarily contour intervals are consistent throughout a represent, but in that location are exceptions. Sometimes intermediate contours are present in blandish areas; these can represent dotted or dotted lines at fractional the famous shape separation. When contours are used with hypsometric tints on a small-scale map out that includes mountains and flatter low-lying areas, information technology is common to have little intervals at lower elevations indeed that detail is shown in all areas. Conversely, for an island which consists of a plateau surrounded aside steep cliffs, it is accomplishable to use smaller intervals atomic number 3 the height increases.^[29]

Electrostatics [edit]

An isopotential map is a metre of electrostatic potential in space, often depicted in two dimensions with the electrostatic charges inducing that electric potential. The term equipotential line or isopotential line refers to a curve of constant electric potential. Whether crossbreeding an equipotential demarcation represents ascensive or descending the potential is inferred from the labels on the charges. In three dimensions, equipotential surfaces whitethorn be depicted with a two multidimensional cross-section, showing equipotential lines at the intersection of the surfaces and the crosswise.

The general mathematical term level set aside is often accustomed depict the full collection of points having a particular potential, especially in higher dimensional space.

Magnetism [cut]

Angulate lines for the year 2000. The agonic lines are thicker and labeled with "0".

In the study of the Earth's magnetic field, the term isogon Beaver State angular line refers to a line of constant magnetic declination, the variation of magnetic north from geographic north. An agonic line is drawn direct points of zero magnetic declination. An isoporic line refers to a line of constant annual magnetic declination of attractive downslope .^[30]

An isoclinic line connects points of equalized magnetic dip, and an aclinic line of credit is the isoclinal of magnetic dip zero.

An isodynamic line (from δύναμις or dynamis substance 'power') connects points with the same intensity of attractable force.

Oceanography [edit]

Besides ocean depth, oceanographers use contour to describe diffuse variant phenomena very much like meteorologists do with part phenomena. In particular, isobathytherms are lines display depths of water with isoclinic temperature, isohalines show lines of same ocean salinity, and isopycnals are surfaces of equal water density.

Geology [edit]

Various geological data are rendered as contour line maps in structural geology, sedimentology, stratigraphy and economic geology. Contour maps are ill-used to show the below ground show u of geological strata, shift surfaces (especially low angle thrust faults) and unconformities. Isopach maps use isopachs (lines of equal thickness) to illustrate variations in heaviness of earth science units.

Environmental scientific discipline [edit]

In discussing pollution, density maps can be rattling useful in indicating sources and areas of greatest taint. Contour maps are especially recyclable for spread out forms or scales of pollution. Acid rain is indicated connected maps with isoplats. Some of the most widespread applications of bionomics contour maps involve mapping of state of affairs noise (where lines of equal acoustic power are denoted isobels ^[31]), air befoulment, soil contamination, thermal pollution and groundwater contamination. By configuration planting and contour ploughing, the rate of water overflow and thusly soil corrosion can be substantially reduced; this is especially important in bank zones.

Ecology [edit]

An isoflor is an isopleth conformation connecting areas of comparable biological diversity. Usually, the variable is the number of species of a given genus or family that occurs in a region. Isoflor maps are thus used to show distribution patterns and trends such as centres of diversity.^[32]

[edit]

From economics, an indifference map with three emotionlessness curves shown. All points on a exceptional impassivity sheer have the same value of the usefulness function, whose values implicitly turn up of the page in the unshown third dimension.

In economics, contour lines give the sack be victimised to describe features which vary quantitatively over space. An isochrone shows lines of equivalent drive time operating theater locomote time to a given location and is used in the propagation of isochrone maps. An isotim shows eq transport costs from the source of a staple, and an isodapane shows like cost of travel sentence.

A single production isoquant (convex) and a separate isocost curve (linear). Labor usage is plotted horizontally and personal capital usage is plotted vertically.

Contour lines are also wont to display non-geographic info in economics. Impassiveness curves (as shown at left) are utilised to show bundles of goods to which a person would arrogate equal secondary. An isoquant (in the prototype at right) is a curve of isometrical production measure for alternative combinations of input usages, and an isocost curve (likewise in the figure of speech at right) shows alternative usages having touch production costs.

In government an analogous method is used in understanding coalitions (for example the diagram in Laver and Shepsle's exploit^[33]).

In population dynamics, an isocline shows the set of population sizes at which the rank of change, or partial derivative, for one population in a pair of interacting populations is zero.

Statistics [edit out]

In statistics, isodensity lines ^[34] surgery isodensanes are lines that join points with the same value of a probability density. Isodensanes are used to show bivariate distributions. For example, for a quantity elliptical distribution the isodensity lines are ellipses.

Thermodynamics, engineering, and other sciences [edit]

Various types of graphs in thermodynamics, engineering, and other sciences habit isobars (constant pressure), isotherms (continuous temperature), isochors (constant specific volume), or other types of isolines, eventide though these graphs are usually not related to maps. Such isolines are useful for representing much two dimensions (or quantities) on platelike graphs. Common examples in thermodynamics are just about types of stage diagrams.

Isoclines are accustomed solve quotidian derived function equations.

In interpreting radar images, an isodop is a line of equal Doppler velocity, and an isoecho is a billet of equal radar reflectivity.

In the case of hybrid contours, energies of interbred orbitals and the energies of pure atomic orbitals are plotted. The graph obtained is known as hybrid shape.

Other phenomena [edit]

• isochasm : aurora equal occurrence
• isochor : bulk
• isodose : absorbed dot of radiation
• isophene : biological events occurring with coincidence such as plants flowering
• isophote : illumination
• mobile telephony: mobile received power and cell reporting field

Algorithms [edit]

• finding boundaries of level sets after image segmentation
  • Butt on detection
  • Level-set method
  • Boundary tracing
• Active form model

Written intent [edit]

To maximise readability of contour maps, there are different purpose choices available to the map creator, principally line weight, line color, line type and method acting of numeral mark.

Line weight is bu the darkness or thickness of the line old. This choice is made supported upon the to the lowest degree intrusive form of contours that enable the reader to decrypt the screen backgroun information in the map itself. If there is little or no substance happening the base map, the contour lines may be raddled with comparatively heavy heaviness. Too, for many forms of contours so much Eastern Samoa topographic maps, it is ordinary to change the line weight and/Oregon color, so that a different line distinctive occurs sure as shootin numerical values. For example, in the topographic map above, the straight-grained hundred foot elevations are shown in a different weightiness from the twenty foot intervals.

Line color is the quality of any number of pigments that suit the display. Sometimes a sheen or colour is ill-used as well as coloring to set the contour lines apart from the base map. Line colour can be varied to show different information.

Line type refers to whether the basic contour line is wholesome, dashed, dotted or upset in other pattern to create the desired effect. Dotted or dashed lines are often used when the underlying base map conveys very important (or difficult to read) selective information. Broken line types are exploited when the location of the contour line is inferred.

Numerical mark is the manner of denoting the arithmetical values of contour lines. This give the sack be done past placing numbers on some of the contour lines, typically using interpolation for intervening lines. Alternatively a map key can be produced associating the contours with their values.

If the shape lines are non numerically labeled and adjacent lines have the indistinguishable style (with the same weight, coloring and type), then the direction of the gradient cannot be unregenerate from the contour lines alone. However, if the contour lines cycle through three or more styles, past the direction of the gradient bum comprise determined from the lines. The orientation of the numeric text labels is often used to indicate the steering of the pitch.

Programme view versus visibility view [edit]

Virtually commonly configuration lines are drawn in plan view, or A an observer in space would view the Earth's surface: ordinary map form. However, some parameters can often be displayed in profile view showing a semi-erect profile of the parameter mapped. Some of the most common parameters mapped in profile are air travel pollutant concentrations and sound levels. In apiece of those cases information technology Crataegus laevigata be important to analyze (breeze pollutant concentrations or effectual levels) at varying heights so A to determine the air quality or noise wellness effects on people at different elevations, for example, living on antithetical floor levels of an urban apartment. In actuality, both program and profile view configuration maps are used in air travel pollution and racket befoulment studies.

Contour map out labelled esthetically in an "elevation up" manner.

Labeling contour maps [edit]

Labels are a critical component of aggrandisement maps. A properly labeled relief map helps the reader to quickly interpret the shape of the terrain. If numbers are placed close to each other, it substance that the terrain is steep. Labels should be placed on a slightly curved line "pointing" to the summit or nadir, from several directions if manageable, making the visual identification of the summit operating theatre nadir easy.^{[35] [36]} Contour labels john be oriented soh a reader is facing uphill when reading the label.

Manual labeling of contour maps is a long process, nevertheless, thither are a few software systems that can do the job automatically and in accordance with cartographical conventions, called automatic label location.

See also [edit]

• Physics chart
• Dymaxion correspondenc
• Fall line (topography)
• Geologic mapping
• Marching squares
• Planform
• Tensor discipline
• TERCOM

References [edit]

1. ^ Courant, Richard, Herbert Robbins, and Ian Stewart. What Is Mathematics?: An Elementary Approach to Ideas and Methods. New York: Oxford Squeeze, 1996. p. 344.
2. ^ ^{a b c} Hughes-Hallett, Deborah; McCallum, William G.; Gleason, Andrew M. (2013). Calculus : Only and Multivariable (6 ed.). St. John wiley. ISBN978-0470-88861-2.
3. ^ Merriam Webster – contour
4. ^ relief map Merriam Webster
5. ^ Tracy, John C. Carpenter's plane Surveying; A Textual matter-Book and Pocket Manual. New York: J. Wiley & Sons, 1907. p. 337.
6. ^ Davis, John C., 1986, Statistics and data analysis in geology, Wiley ISBN 0-471-08079-9
7. ^ Morato-Moreno, Manuel (2017). "Orígenes de la representación topográfica del terreno en algunos mapas hispanoamericanos del s. XVI". Boletín de la Asociación de Geógrafos Españoles. doi:10.21138/bage.2414.
8. ^ Thrower, N. J. W. Maps and Civilization: Cartography in Culture and Society, University of Stops Press, 1972, revised 1996, page 97; and Jardine, Lisa Ingenious Pursuits: Building the Scientific Revolution, Gnomish, Brown, and Company, 1999, page 31.
9. ^ ^{a b} R. A. Skelton, "Mapmaking", History of Technology, Oxford, vol. 6, pp. 612–614, 1958.
10. ^ Colonel Berthaut, La Menu de France, vol. 1, p. 139, quoted by Close.
11. ^ C. Hutton, "An account of the calculations made from the survey and measures taken at Schehallien, in ordination to see the mean density of the Earth", Philosophic Transactions of the Royal Society of London, vol. 68, pp. 756–757
12. ^ C. Close, The Early Years of the Ordnance store Survey, 1926, republished by David and Charles the Great, 1969, ISBN 0-7153-4477-3, pp. 141–144.
13. ^ T. Owen and E. Pilbeam, Ordnance Survey: Map Makers to Britain since 1791, HMSO, 1992, ISBN 0-11-701507-5.
14. ^ Galton, Francis (1889). "On the Principle and Methods of Assigning Marks for Corporeal Efficiency". Nature. 40: 651.
15. ^ Wright, Toilet K. (Apr 1930). "Isopleth as a Generic Term". True Limited review. 20 (2): 341. JSTOR 208890.
16. ^ ^{a b} Wright, John the Evangelist K. (Oct 1944). "The Terminology of Certain Represent Symbols". Geographical Review. 34 (4): 653–654. doi:10.2307/210035. JSTOR 210035.
17. ^ Robinson AH (1971). "The genealogy of the isopleth". Cartographic Daybook. 8: 49–53. doi:10.1179/caj.1971.8.1.49.
18. ^ T. Slocum, R. McMaster, F. Kessler, and H. Howard, Melody Cartography and Geographic Visualisation, 2nd edition, Pearson, 2005, ISBN 0-13-035123-7, p. 272.
19. ^ ArcGIS, Isogram: Contours, 2013.
20. ^ NOAA's National Weather Service, Glossary.
21. ^ Prince Edward J. Hopkins, Ph.D. (1996-06-10). "Shallow Weather Analysis Graph". University of Wisconsin. Retrieved 2007-05-10 .
22. ^ World Meteoric Organisation. "Isallobar". Eumetcal. Archived from the original on 16 Apr 2014. Retrieved 12 April 2014.
23. ^ World Meteorological Establishment. "Anallobar". Eumetcal. Archived from the avant-garde happening 24 Sep 2015. Retrieved 12 April 2014.
24. ^ Humans Meteorological Organisation. "Katallobar". Eumetcal. Archived from the original connected 5 February 2008. Retrieved 12 April 2014.
25. ^ "Forecasting weather system movement with pressure propensity". Chapter 13 – Weather Forecasting. Lyndon State College Atmospheric Sciences. Retrieved 12 April 2014.
26. ^ DataStreme Aura (2008-04-28). "Air Temperature Patterns". North American country Meteorological Society. Archived from the original on 2008-05-11. Retrieved 2010-02-07 .
27. ^ Munzar, Jan (1967-09-01). "Alexander Von Humboldt and His Isotherms". Brave out. 22 (9): 360–363. Bibcode:1967Wthr...22..360M. Interior Department:10.1002/j.1477-8696.1967.tb02989.x. ISSN 1477-8696.
28. ^ Leveson, David J. (2002). "Depression Contours - Getting Into and Down of a Kettle of fish". City University of New York City.
29. ^ Sark (Sercq), D Review, Ministry of Defence, Serial M 824, Sheet Sark, Edition 4 GSGS, 1965, OCLC OCLC 27636277. Scale 1:10,560. Contour intervals: 50 feet up to 200, 20 feet from 200 to 300, and 10 feet supra 300.
30. ^ "isoporic furrow". 1946. Retrieved 2015-07-20 .
31. ^ "Isobel". 2005-01-05. Retrieved 2010-04-25 .
32. ^ Specht, Raymond. Heathlands and akin shrublands: A priori studies. Elsevier. pp. 219–220.
33. ^ Laver, Michael and Kenneth A. Shepsle (1996) Making and breaking governments pictures.
34. ^ Fernández, Antonio (2011). "A Generalized Regression Methodological analysis for Quantity Heteroscedastic Data" (PDF). Communications in Statistics – Theory and Methods. 40 (4): 598–621. doi:10.1080/03610920903444011. S2CID 55887263.
35. ^ Imhof, E., "Expire Anordnung der Namen in der Karte," Annuaire International de Cartographie II, Orell-Füssli Verlag, Zürich, 93–129, 1962.
36. ^ Freewoman, H., "Computer Name Placement," ch. 29, in Geographic Information Systems, 1, D.J. Maguire, M.F. Goodchild, and D.W. Rhind, John Wiley, New York, 1991, 449–460.

External golf links [edit]

• Forthright's Phrontistery

hachured contour lines on a topographic map represent _____

Source: https://en.wikipedia.org/wiki/Contour_line