flow and wave systems are presented, and its erratic 

 behavior when used as a wave direction gage under 

 natural conditions at Long Branch, N. J. and Hunting- 

 ton Beach, Calif, is discussed. 



NO. 19 - July 1950 



II -B "Submarine Topography and Sedimentation in the Vicinity 

 C of Mugu Submarine Canyon, California" by D. L. Inman 



The bathymetry of the adjacent shelf and the submarine 

 canyon heads adjacent to the beach and lagoon is pre- 

 sented and described. Mugu Submarine Canyon has two 

 branches at its head, each having an isolated ridge 

 protruding from the floor parallel to the canyon axis. 

 The relation of sediment type and bottom topography is 

 investigated. 



NO. 20 - July 1950 



II-C |*Beach Cycles in Southern California" by Francis P. Shepard 



Prom a mass of records and data accumulated on California 

 beaches, salient features observed are discussed and their 

 interpretation attempted. Features discussed include 

 seasonal changes both offshore-onshore and lateral move- 

 ment, long term trends, changes associated with engineer- 

 ing structures, and relationship of permanent and tempo- 

 rary losses. 



NO. 21 - November 1950 



I&II-A "The Interpretation of Crossed Orthogonals in Wave Refraction 

 Phenomena" by Dr. Willard J. Pierson, Jr. 



The theory of wave refraction is critically reviewed. 

 Analytical examples of caustic curves are given, and 

 it is shown that the theory of wave refraction as based 

 upon geometrical optics fails at the caustic. More re- 

 fined techniques lead to the result that there is a phase 

 shift through the caustic and that the waves remain finite 

 in height, and possible results of the solution are dis- 

 cussed. Results of other investigators are applied to a 

 model study of refraction of waves over a clock glass, and 

 the 180-degree phase shift through a caustic is demonstrated. 

 The orthogonal method of refraction analysis is applied for 



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