The gradient of the surface of the ground, given either as the angle the surface makes with the horizontal or as the ratio, expressed as a fraction or percentage, between the vertical rise or fall and the horizontal distance in which the rise or fall has occurred. The following terms are used to qualify slope:- Level .......... ......... 0 to 5 Gentle .......... ......... 5 to 10 Moderate .......... ......... 10 to 15 Steep .......... ......... 15 to 25 Very steep .......... ......... 25 to 45 Precipitoius .......... ......... Over45 Cf. Aspect