APPENDIX. 463 



value of his records : though, in desert tracts, his know* 

 ledge of surveying may sometimes be required. Thence 

 also the most recent map should be selected ; since 

 the works of man, at least, are subject to changes, 

 especially in improving countries; often causing egre- 

 gious confusion, as at" present in Scotland. 



Excepting military maps, few contain the forms of 

 ground, so important to a geologist. The want of 

 objects in mountainous countries is but imperfectly 

 supplied by rivers ; and, without that, an accurate 

 geological record will always be difficult. The nature, 

 positions, and boundaries of rocks, are often indeed so 

 intimately connected with these forms, that a military 

 survey becomes invaluable ; while they who have ex- 

 perienced its utility, will often gladly undertake this 

 previous labour. It is to be wished that map-makers 

 may at length become sensible of their neglect on 

 this point ; and that their conjectural symbols may be 

 replaced by delineations to render their works of use 

 to more than the mere traveller. To the geologist, 

 the blackness of maps is also a serious grievance ; as 

 it deprives him of the use of broken and delicate tints, 

 in distinguishing among numerous rocks. Nor is it 

 required ; since any ground can be fully expressed 

 without it, as is proved by the recent maps of France 

 and Italy : while, if often arising from misplaced am- 

 bition in the engraver, it is more frequently the fault 

 of superintendents, ignorant of art. And a similar 

 evil arises from loading them with symbols of forests 

 and wastes, obscuring the much more important forms 

 of the ground. 



All boundaries of rocks should be laid down, in the 

 field, in the selected colours: and unless this be done, 

 the produce will deserve no confidence : while the ob- 

 server himself will soon find that he can ensure accu- 



