ABSTRACT
The first stage of terrain classification is scale definition. Landscape features vary in size by several orders of magnitude, from continents at one extreme to particles of sand or clay at the other. Tricart (1965b) has suggested an eight-level scalar hierarchy and Haggett et al. (1965) a subdivision of the earth’s total surface area successively by powers of 10 to give ‘Ga scale values’ or ‘G’. The area of the globe is 5.098 × 108 km2. This is assigned a value of 0. One-tenth of this (5.098 × 107) is 1, one-hundredth is 2 and so on. G can be determined from formula [2.1] for any given area (Ra) being considered. https://www.w3.org/1998/Math/MathML"> G = 8.7074 - log R a ( km 2 ) G = 10.7074 - log R a ( ha 2 ) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315841229/a5bf97c8-3295-4fa0-8a7f-c7c75a8463e7/content/math_1_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> Tricart orders and Ga scale values for a scalar hierarchy of land regions are shown on Table 2.1. Landscape Scales (after Tricart 1965 and Haggett et al. 1965)
|
Order |
Area (km2) |
Ga scale value |
Example |
|---|---|---|---|
|
I |
107 |
1.71 |
Australian continent, humid temperate zone |
|
II |
106 |
2.71 |
American Piedmont, North European Plain |
|
III |
104 |
4.71 |
Lowland Britain, Florida Peninsula |
|
IV |
102 |
6.71 |
Weald, Cape Cod |
|
V |
10 |
7.71 |
North Downs, Nantucket |
|
VI |
10-2 |
9.71 |
Terrace, scarp, fan |
|
VII |
10-6 |
13.71 |
Soil polygon, tussock, runnel |
|
VIII |
10-8 |
15.71 |
Pebble, weathering detail on rock |
