478 University of California Publications in Agricultural Sciences [Vol.3 



sider the differences between the older and the recent survey of two 

 localities east of Los Angeles. The notes were made by C. J. Zinn, 

 a member of the party which made the recent survey : 



Locality A — About 15 square miles with Eaton Wash on the west, center of 

 Monrovia on the east, mountains on the north, and a line about 3 miles south of 

 mountains as the south boundary. The old survey 40 has four types of three series 

 and two miscellaneous types: San Gabriel gravelly loam, San Gabriel gravelly 

 sand, Placentia sandy loam, San Joaquin black adobe, and Biverwash and Moun- 

 tains. The new survey (1915, unpublished) has 13 types of 6 series and 3 mis- 

 cellaneous types : Hanford stony sand, gravelly sand, loam, sandy loam, fine 

 sandy loam, and sand; Tejunga stony sand; Zelzah loam and stony loam; Pla- 

 centia loam, Holland loam, Chino loam and silt loam. The miscellaneous types 

 are Bough Mountain land, Bough Broken land, and Biverwash. 



Locality B — In the city of Pasadena, comprising about 3.5 square miles, with 

 the southwest corner at the center of the city. The old survey 41 shows San 

 Gabriel loam occuping about 0.6 of the area, San Gabriel gravelly sand about 0.3, 

 and Placentia sandy loam about 0.1. The new survey (1915, unpublished ) shows 

 Zelzah gravelly loam occupying about 0.9 of the area, Zelzah loam about 0.1, with 

 a very small body of Holland loam. The older survey showed a recent alluvial 

 soil where the recent one shows an old valley filling soil. 



Besides these errors (detected as such by the practical man. who 

 might attempt to use the soil maps in the field) there are in addition 

 those of another nature which were the source of much criticism in the 

 earlier history of the survey — the so-called "procrustean classification" 

 criticism of Hilgard. 42 Due apparently to an insufficient study of the 

 soils of the United States, there was the attempt to classify in the same 

 series soils of widely differing properties — differences of an important 

 nature being ignored. 



At the present time there is an increasing tendency toward limit- 

 ing series groups of soils to a more or less definite climatological 

 region. In this connection see the later changes in the correlation of 

 many soils. 43 These changes tend to limit the geographic range of the 

 series, and make these series narrower and more exact. Moreover, it 

 is understood that as the knowledge of the soils has increased, the 

 changes in correlation have been proceeding rapidly since the above 

 list was issued. This indicates that as the facts accumulate the "pro- 

 crustean classification" criticism is losing its force. 



40 Field Operations of the U. S. Bur. of Soils, 1901, San Gabriel sheet. 

 « Ibid. 



4 2 Hilgard, E. ~W., and Loughridge, B. H., Proc. Second Intern. Agrogeol. 

 Conf., Stockholm, 1910, pp. 228-29; Hilgard, E. W., U. S. Office Exp. Sta., Bull. 

 142 (1904), p. 119; Hilgard, E. W., Proc. First Intern. Agrogeol. Conf., Budapest, 

 1909, pp. 52-54. 



43 TJ. S. Bur. Soils, Bull. 96, 1913. 



