meter was in somewhat intermittent operation at the end of Scripps pier 
between 1937 and 1910. Various other records are available but their nature 
has made it seem inadvisable to consider them in relation to the present 
study. 
The current measurements were made in a locality where conditions are 
greatly influenced by the presence of two submarine canyons (figure 1). The 
wave convergence just south of Scripps pier causes a predominant northward 
current which extends ordinarily as far as Scripps pier before turning sea- 
ward into a rip current. The latter is found most frequently a few hundred 
feet north of the pier but turns seaward at the pier on many occasions. The 
pier has some special influence both in retarding longshore flow and in deflect- 
ing currents seaward. The most common deep water wave approach in the area is 
from the west or northwest as is also the wind. Both of these factors tend 
to produce southerly currents although the wave fronts are much influenced by 
the canyon topography. Southerly wave approach is frequent during the summer 
but not important in the Scripps area due to screening by Pt. La Jolla. During 
most of the year the winds are light, that is, less than 10 miles per hour, 
but occasional winds have velocities up to 0 miles an hour. Almost all of 
the storms come from the northwest. 
The much shorter records of observations at Crystal Pier were made in 
an area where the submarine contours are essentially straight and parallel 
to the shoreline. Therefore these serve to check the results obtained at 
Scripps Pier where submarine canyons influence the currents. 
Statistical Relations of Currents along the Pier 
Current Velocities. 
The 800 measurements of velocities just inside, and outside of the 
breakers, and at the end of the pier allow a very substantial comparison 
of velocity and direction of these different environments. Figure 2 shows a 
cumulative curve comparing the velocities regardless of direction at the 
three localities. It will be noted that the median in the surf zone is six 
times as high as that outside the breakers, but that the velocities do not 
differ greatly between the zone just beyond the breakers, and at the end 
of the pier. Similarly the times of no measurable current are rare inside 
the breakers but constitute 17 per cent just outside and 11 per cent at the 
pier end. There were only 23 days when the current just outside the breakers 
or at the end of the pier was stronger than that in the surf zone. On nine 
of these occasions there was a strong wind which seemsto have much more 
influence on current velocities outside the surf zone than it does inside. 
On 5 other of these days the stronger current was in the opposite direction 
from that in the surf zone and on two other occasions there was little if 
any current in the surf zone. 
Current velocities increase roughly with breaker height as is indicated 
by a plot of median velocities for each foot of breaker height in the surf 
zone (figure 3). This is only a trend, however, and there are a consider- 
able number of days when relatively strong currents, mostly northerly, were 
9 
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