SAND DUNES. 57 



count} 7 road diverted in order to avoid the dunes, which at this point 

 are of great size. 



At Eureka the peninsula which almost incloses the harbor (see Map 

 III) is chiefly composed of sand dunes, which do not, however, 

 encroach on the mainland, though possibly doing some damage to the 

 harbor itself by silting up the channel.' 1 



The conditions at Humboldt Bay are described in the following 

 extract : b 



Humboldt Bay is 14 miles in length and from one-half mile to 4 miles in width. 

 It has a tidal area of 28 miles and 35 linear miles of navigable channels. It is situ- 

 ated near the center of the coast line of Humboldt County and extends nearly 

 parallel therewith, being separated from the ocean by two narrow peninsulas of 

 sand. Being so completely landlocked, this harbor is of the utmost importance 

 to a coast so barren of good harbors as is the Pacific; but its usefulness has in the 

 past been seriously impaired by shifting sand bars, which obstructed its entrance, 

 and by the shallowness of some of its inner channels. In 1889 the General Gov- 

 ernment began improving the entrance to the harbor by extending two jetties of 

 rock, one on each side of the channel, so as to confine the waters to a permanent 

 way. This work was completed in September, 1899, at a cost of more than 

 $2,000,000. 



Eel River for a few miles of its lower course is navigable for small vessels, and 

 has at several periods had regular steamer connection with San Francisco; but its 

 navigation is often interrupted by the formation of sand bars at its mouth. 



At Crescent Cit} 7 the mouth of a creek has been completely closed 

 by drift sand, forming a large lagoon (Plate VI, fig. 1) and causing 

 the winter flooding of extensive grazing lands. The protection 

 afforded b} 7 a native pine forest appears to have prevented the 

 encroachment of sand on the farm lands at this point. Should this 

 timber be cut at any time for fuel, which is likely to be done as popu- 

 lation increases and fuel becomes more scarce, a large tract of dairy 

 land would be jeopardized. Precautions should be taken against 

 such a result. 



Big Lagoon, at the mouth of Maple Creek, Humboldt County, may 

 perhaps have been formed in the same way as the lagoon at Crescent 

 City. 



Native sand binders. — The following native plants grow naturally 

 on the sand dunes, and act to a greater or less extent as sand binders: 



Abronia latifolia (yellow sand verbena) (Plate VI, fig. 2) is com- 

 mon at the mouth of the Garcia River; of some value as a sand binder 

 on account of its heavy, prostrate stems and large, flat leaves, but not 

 the best plant for the purpose, as it does not root at the nodes, and 

 oftentimes the sand is blown away from beneath the branches, leav- 

 ing the large, fusiform roots exposed to wind and sun. 



Arctostaphylos uva-ursi is a prostrate species, forming large mats 

 on almost pure drift sand on the sand spit opposite Eureka, where it 



a Since the above was written complaint has been received by the writer of 

 serious injury to lumber mills caused by the drift sands at this point. Reclama- 

 tion work has already been started by the planting of beach grass. 



b " Resources of California." 



