OBTAINING THE DATA — FIELD WORK 319 



a degree of accuracy consistent with a reasonably close utilization 

 of the forage crop, the mapper may pace through each section 

 either on foot or on horseback (usually on foot) ; or, if the topog- 

 raphy is rugged, he may ascend points from which the types 

 may be readily sketched in. In the first instance, the worker 

 passes through each section twice at a distance not greater than 

 half a mile apart, collecting the data as he goes and checking his 

 pacing on surveyed lines if these are available. 



In surveyed country the examiner starts from an established 

 Land Office corner, keeping his position located either on a 2- or a 

 4-inch-scale map. (The U. S. Forest Service provides a special 

 form for this purpose.) The sketching consists in recording the 

 topography, types^ and cultural features. In addition, the 

 density of the ground cover and certain other factors are noted 

 on the special form used, and these data are subsequently dis- 

 cussed in the descriptive report. Elevations are recorded by 

 means of an aneroid barometer. 



In unsurveyed country traverse fines are run in cardinal 

 directions from a station which is permanently monumented, so 

 that the station may be tied in and the traverses adjusted to 

 later surveys. Along the traverse fines, stakes may be set at 

 intervals of half a mile, these distances being carefully measured. 

 For convenience the stakes are numbered and may carry the 

 elevation where located. The traverse lines being established, 

 the examiner starts from stakes one mfie apart and records the 

 data in the manner described for the use of the gridiron method 

 in surveyed country.^ 



The traverse-sketching method is based upon traverse fines so 

 located as to permit the examiner to sketch in the country on 

 each side of the fine. Traverse lines may be estabfished in 

 rugged localities by means of compass and chain or by stadia, 

 the method depending upon the topography and the character 

 of the vegetation. These traverse lines may be located along 

 the main streams, roads, ridges, and trails. These data being 

 available, the examiner proceeds in a manner similar to that of 



1 In the absence of Land Office corners, traverse lines are extended along ridges, 

 creeks, and trails in the manner described, except that the traverse must be plotted 

 and sectionized. 



