28 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
Rainfall rccords—Continued. 
: . Length ,“verage 
Station. Altitude in of record annual pre- 
™ feet, “intyears, ipitation 
Sunnyside__---.--. -2.-- ee oo 764 | 10 | 6.63 
Tacoma __________---_.--_ wo eee eee 213 | 19 44.638 
Tatoosh __.------2 2. oo eee 86 | 20 93.78 
Trinidad __--._.____. ee Soo eee 900 | 1 6.05 
Twin. -.--- 22. 6 | 2 66.50 
Twisp ...--------- 8 1,619 | 1 18.50 
Union City ------2 2-2-2) _ 10 | 11 83.41 
Usk ....1.--.---. oo 2,050 | 5 24,80 
Vancouver _.------.-) (ee eee 50 | 31 38. 74 
Vashon Island.............__......... 110 | 16 41.56 
Walla Walla_....-....-- Doce eee ee a 1,000 | 19 16.77 
Waterville -_...-.-22..8 8 ee | 2° 94 | 15 13. 30 
Wenache_....--..-5-. 8. _ 1, 169 | 6 15.52 
Whatcom ........-- ee oo 60 | 9) 81.9% 
Wilbur. .---. 22-2. Lo eee eee —— 2, 208 6 | 16. 20 
Zindel._.._--- 2-2 a 715 | 30 17. 67 
Lewis'on, Idaho.) 757 11 13. 82 
Arlington, Oreg 9-8 | 855 — 14 9.11 
The Dalles, Oreg_..-. 22-88 12 30 — 15,09 
Umatilla. Oreg_..-- 26s Lee ee eee eee ee eee] 340 | 17 8.84 
Astoria, Oreg.-----8 oo 50. 45 87. 41 
The rainfall map (PI. V) is based mainly on the above records, 
but over mountainous regions where no records have been made 
the lines drawn are based on topography. Owing to the great vari- 
ation in rainfall caused by mountains and to a less extent by deep 
‘anyons, which often make great differences within small areas, the 
rainfall map is drawn on broad lines. Enough is known of these 
local differences in rainfall caused by topography to make it certain 
that an accurate map of Washington to show these smaller differ- 
ences would be a very complex affair. 
The larger differences in the normal annual precipitation are 
clearly shown by the map. As a whole, western Washington has a 
heavy rainfall while that of eastern Washington is light. The coast 
region has the greatest precipitation, heaviest on the western slope 
of the Olympic Mountains. The region immediately to the north- 
east of these mountains has a correspondingly light rainfall. No 
satisfactory records are available for the precipitation in the higher 
parts of the Cascade Mountains. Presumably it is between 70 and 
90 inches. ; 
In eastern Washington perhaps the most striking feature is the 
suddenness with which the precipitation decreases east of the crest of 
the Cascades. 
The area over which the rainfall is less than 10 inches is practically 
identical with the Upper Sonoran life area. 
As compared with the rest of the United States the narrow strip 
immediately along the ocean has the maximum amount of rainfall, 
