178 CARNEGIE INSTITUTION OF WASHINGTON. 



ured (both by laboratory determination and by the field pendulum) 

 so variable as to furnish a remarkable opportunity for application of the 

 theory of isostatic adjustment. 



These five studies together constitute a comprehensive approach to 

 a discussion of crustal movement of a magnitude and scope beyond 

 anything hitherto attempted, and for which California offers an un- 

 paralleled opportunity. To carry out a plan of this magnitude no 

 single agency is adequate. 



It is, therefore, recommended that the Carnegie Institution invite: 



(1) The cooperation of the U. S. Coast and Geodetic Survey to 

 undertake : 



(a) A system of primary triangulation and precise levels, (1) in the San 

 Francisco region connecting with a permanent base east of the moun- 

 tains (Reno), (2) southward along the fault zone to include the region 

 of complex faulting in the vicinity of Los Angeles, (3) thence eastward to 

 connect with an appropriate zone of no movement east of the mountains. 



(6) The establishment at suitable localities of new lines of monuments at 

 right angles to the San Andreas fault, the San Jacinto fault, and per- 

 haps others, for the purpose of measuring displacements there. 



(c) To continue its pendulum and plumb-line observations in close co- 

 operation with the work above outlined. 

 *{d) To make a series of deep-sea soundings north and south from Mon- 

 terey Bay to determine the direction and height of the fault scarp 

 forming the termination of the continental shelf in that region. 



(2) The cooperation of the United States Geological Survey to 

 determine geological relations in the California fault areas. 



(3) The cooperation of the California Institute of Technology, the 

 Mount Wilson Observatory, and other agencies, if necessary, in the devel- 

 opment of seismometric recording apparatus for study of local tremors. 



(4) The cooperation of the Lick Observatory and the Ukiah Ob- 

 servatory for the continuation of their observations of crustal drift. 

 At the Lick Observatory it is particularly recommended that a suitable 

 special instrument be provided for this purpose. 



It is recommended further that the present Research Associate of 

 the Institution, Mr. H. O. Wood, be continued in the field in southern 

 California to gather such information from local sources as will facilitate 

 the location of the instruments referred to in paragraph 3 above and 

 the appropriate triangulation stations for the discovery of displace- 

 ments in the fault zone in that region. 



ANDERSON, J. A.. 



ARNOLD. RALPH, 



CAMPBELL, W. W., 



DAY, ARTHUR L. (Chairman), 



LAWSON, A. C, 



MILLIKAN, R. A., 



REID, HARRY FIELDING, 



WILLIS, BAILEY, 



Advisory Committee in Seismology. 

 Carnegie Institution of Washington, 



October 1921. 

 *Willis dissenting. 



