west direction. A prominent canyon (Indian Canyon) cuts through the 

 cliffs to the beach at the study site so the central range line was loca- 

 ted near the mouth of the canyon for geographic reference. Another range 

 line was located 1,135 feet (546 meters) south of the Indian Canyon range 

 line, and the third range line was located 2,200 feet (670 meters) north of 

 the Indian Canyon range line. These range lines were named South Range, 

 Indian Canyon Range, and North Range to designate their geographic position 

 relative to Indian Canyon (Figure 2) . 



A level line survey was made from an established U. S. Coast and 

 Geodetic Survey bench mark to South Range along the top of the sea cliff. 

 This survey was made using a transit, rod and tape with calibration 

 marks of ±0.01 foot (±0.5 cm) on horizontal and vertical distances. The 

 permanent position and elevation of two points were established on the 

 flat terrace above the cliff on South Range. These points are: 



a. A point located at the base of the seaward monument of 

 the U.S. Navy measured nautical mile course. 



b. A point located by a pipe driven into the ground within 

 a few feet of the cliff edge. 



The elevation of the bench mark on the beach at South Range was deter- 

 mined by using a trigonometric solution. The vertical angle from the 

 established point at the top of the cliff and a point on the beach was 

 accurately measured with a transit. Then the "thin air ? ' distance between 

 the point at the top and bottom of the cliff was measured with a Hewlett- 

 Packard 3800A Distance Meter. These two measurements allowed the calcu- 

 lation of the vertical distance between the two points to within a frac- 

 tion of a foot . 



The exact location and elevation of the bench marks for Indian Canyon 

 and North Ranges were established by making a level line survey along the 

 beach from the South Range bench mark. The accuracy of the elevation 

 between the bench marks for the three range lines is about 0.01 foot 

 (0.5 cm). Appendix A has a description of the bench marks established on 

 Torrey Pines Beach and the notes from the bench mark surveys. 



Each range line is physically located by two points on the range 

 at beach level. These points are marked by 1/2-inch-diameter stainless 

 steel pipe 5 feet long driven into the ground and cemented in place. 

 The seaward pipe is capped with a brass plug that is labeled as S10 I, 

 SI0 II, and 310 III for South Range, Indian Canyon Range, and North Range, 

 respectively. The landward point on each range line is marked by an open 

 1/2-inch-diameter stainless steel pipe set back from the seaward point. 

 For protection from vandalism and natural erosion, the bench mark pipes 

 were set at the landward edge of the beach and up on the toe of the sea 

 cliff. The pipes were pounded into the present ground surface to reduce 

 their conspicuousness and increase their stability. All of the original 



