POTASH FROM KELP. | 25 
of a pale yellowish brown color, and very brittle texture. The ex- 
tensive kelp beds of the Santa Barbara coast, which are more shel- 
tered from the wind than are most of those farther south, are charac- 
_ terized for the most part by rather light kelp. These latter beds 
_ seem also to deteriorate more in warm summer weather than do any 
others along the coast. 
| Light winds keep the air circulating, thereby preventing overheat- 
- ing of the stratum immediately overlying the water. These winds 
_ splash water over the floating portions of the kelp which are thus 
Yield in hundreds of tons | 
Atmospheric a of 
Movements at \|,000 71 |. Sx=EaaEerEEED arene 
Point Reyes in 
Miles per Month 
14,000 m i. iy i ee eh: ed 
19.0COM |. S2EaREttemaemeres 
Fig. 138.—Variation in yields of kelp with moderate winds, 1916, 1917, and 1918. The 
seal pares refer to yields of wet kelp in hundreds of tons per square mile of area 
arvested. 
kept cool by evaporation. The prevailing northwest wind of the 
central Pacific coast is regarded as one of the chief causes of the up- 
welling and southward drift of cold water along the coast (McEwen, 
4). The southern hmit of this upwelling and the southern lmit 
of Macrocystis are said to coincide very nearly. On account of their 
being the best available index of the prevailing winds of the greater 
_ part of the California coast, the Point Reyes wind records are in- 
cluded in the tables. (See Table 3 and fig. 13). It is very probable 
a, Peele eh aai iF Pee 
| | Yieldin hundreds of tons per square mile! 
7 i 2 A ; 
High Winds at | a 4 
) an D € £ ) | ny | S = 5 ae) . Be i, CoE ae eee Lae eee ie EE hea eee 
Miles per Hour 
(La 
us} 
ley 
Fic. 14.—Variation in yields of kelp with high winds, 1916, 1917, and 1918. The 
. Small figures refer to yields of wet kelp in hundreds of tons per square mile of area 
harvested. 
24.5 |. ER 
that the much lighter winds recorded at San Diego also have consid- 
erable influence on the movement of the adjacent water. (See Table 
4 and figs. 18 and 14.) Often when the wind is blowing from the 
southwest or west, kelp of the type peculiar to the islands is brought 
into the beach at La Jolla in an excellent state of preservation. Such 
winds may also influence the temperature of the water. 
