120 Procecclings of the Royal Physical Society. 



the Bay of San Francisco is changing nncler the influence of 

 the same cause. The desolation which remains after the 

 ground, thus washed, is abandoned, is remediless and appal- 

 ling. The rounded surface of the "bed rock," torn with 

 picks and strewn with huge boulders too large to be removed, 

 shows here and there islands of the poorer gravel, rising in 

 vertical cliffs with red and blue stains, serving to mark the 

 former levels, and astounding the stranger who first sees 

 them at the changes, geological in their nature and extent, 

 which the hand of man has wrought. 



Mr Trowbridge informs me that unless dredging is re- 

 sorted to, it is questionable if the Sacramento ten years 

 hence will be navigable. The bed of the river has been 

 gradually and sometimes even rapidly rising. It is affirmed 

 by some experienced pilots that the bed of the lower river is 

 twenty feet higher than it was twenty-five years ago. The 

 farms on the banks have been seriously injured. " Injunc- 

 tions," even could they have been obtained, would be useless, 

 for gold-mining is too important an industry of California to be 

 checked by any process of law. In some cases, to save them- 

 selves trouble, the miners have bought up the farms, and so 

 their work of digging and w^ashing for gold goes on. The colour 

 of the river water shows that vast amounts of earth are sus- 

 pended in it ; and this is being continually deposited in the 

 beds of rivers, and the current is insufficient to remove it 

 from the channel. Some considerable time since, it w^as 

 found necessary to withdraw the large steamers from the 

 Sacramento trade, and substitute boats of less draught. In 

 time, the river will become shoaled up, as the San Juan, and 

 other Central American rivers have been, by the natural pro- 

 cess of silting, within the last few years. The shallow bays 

 off San Francisco Bay are also getting shoaled. Suisun Bay 

 is already shallow, and in course of time may be converted 

 into cultivatable land, unless the bed of the river should rise 

 faster than the bottom of the bay. 



The shoaling of the Sacramento is only one example 

 of many others wdiich could be cited. Meanwhile, the 

 Californian engineers are devising expedients to meet the 

 numerous difficulties which the case calls for just now, 



