1919] Pendleton: A Study of Sail Types 479 



3. There was a lack of trained men early in the work. This was 

 to be expected. As has been shown, the early surveys were very crude 

 in certain places. It must be added that some of the errors and omis- 

 sions made in the more recent maps are not due to a lack of training, 

 but to the carelessness of the field men with respect to details. 



4. The policy of the Bureau has been to recognize the physical 

 characteristics of the soil as factors in fertility to the virtual exclusion 

 of the chemical or biological factors. Therefore the use of physical 

 criteria is necessary. Besides, the criteria must be such as can be 

 applied in the field, and are: (1) color, (2) texture, determined by 

 rubbing between the thumb and finger, (3) structure, (4) nature of 

 subsoil, (5) presence of hardpan, (6) height of water table, (7) pres- 

 ence of alkali, (8) topography, (9) physiographic form and hence 

 mode of formation, and (10) source of material (sedimentary, igne- 

 ous, or metamorphic rocks). Humus, and the presence or absence of 

 appreciable quantities of lime, also the reaction of the soil (acid or 

 alkaline) are frequently guessed at. These criteria are practically 

 the only ones that can be applied in field work. It is believed that 

 these same criteria indicate the chemical nature of the soil, though 

 there has been no attempt to correlate some of the factors. However, 

 the original work reported in this paper would indicate that the chem- 

 ical nature is not the same, of soils classified the same by the Bureau 

 of Soils criteria. 



5. The desire to limit the number of groups of soils is a wholly 

 sound one. In discussing the problems of classifying soils there 

 should always be kept in mind the fact that some of the problems are 

 not very different, fundamentally, from some of the problems that 

 have been causing perplexity among biologists for a long while. 

 The tendency, as seen in some of the recent surveys, to make the 

 series more inclusive and to introduce the term, phase, is heartily 

 commended. By making the series broader there will he less difficulty 

 in placing a soil in its proper group. The phase will take care of many 

 of the series differences between area and area. 



6. It seems certain that if there were more emphasis placed upon 

 the inspection of the area, during the progress of the field work and 

 after its completion, there would be a much closer approach to 

 accuracy throughout the map and report. At the present time the 

 field man is not closely checked up. The careless or indifferent worker 

 can map more or less as he pleases, especially in the out-of-the-way 

 places. 



