• Dale Hill

Mt Woodson Station

Updated: Jan 30

Over the course of three different outings, I was able to successfully recover all of the remaining survey marks for the Mt Woodson Station. The National Geodetic Survey (NGS) maintains an online database of survey marks assigned a permanent identification number (PID) I was able to find 6 of the 8 recorded marks I found listed in the database, plus a separate, yet related station nearby, giving me a total of 7 recovered (found) marks.

So What's a Station?

According to the Bureau of Land Management Glossary of Mapping Terms, the primary definition of a Station is a point whose position has been or will be determined by surveying methods. These survey points are commonly identified using a round brass disc set in concrete, bedrock, or stainless steel rods that are driven to the point of refusal to establish its measured height or elevation above (or below) a reference surface approximating mean sea level. A Triangulation Station is one that has been calculated by using other marks to create a network of triangles to determine distances.

The NGS (and its predecessor agencies) have established these benchmarks to identify the vertical component, referred to as the Vertical Datum, of the National Spatial Reference System (NSRS). Having accurate elevation data is important in several fields including major infrastructure engineering and construction, agriculture, and emergency planning.

Triangulation Station

This is a snippet from the Basic Metadata of the Woodson datasheet (often referred to as the DSDATA) In this instance, the WOODSON Station has a Permanent ID or PID of DX5028 and is searchable in the database.

This is another snippet from the body of the same datasheet that shows nearby survey marks, this section is usually referred to as the "box score" for the ASCII text box which surrounds the information. This is the Azimuth Marks Section and will include the Primary Azimuth Mark (if there is one) and other Reference Objects. All azimuths are referenced clockwise from north, this lists 7 different reference objects to the station.

Note: The NGS offers a PDF document that explains all the various components of The DSDATA Format, it's not necessarily 'edge of your seat reading' but becoming familiar with it will be a big help in reading and understanding these documents.

The Description and Recovery Section of the datasheet provide the most useful information about how to find the station, this quote is the first description of the Woodson station as the disc was set (and the survey monumented) in 1938. The datasheet will also provide current survey control information for the station, providing latitude and longitude as well as the elevation in both meters and feet. Keep in mind, most of these were placed long before GPS technology was available, so you may find that the given coordinates are not exactly where the mark is. If you see the term "Scaled" next to a set of coordinates, they were calculated from a map with an estimated accuracy of + / - 6 seconds.

Woodson Station Description

Described by the U.S. Coast and Geodetic Survey 1938: Station is located on summit of high rocky peak known as Mount Woodson and Cobble Back Mount, 9 miles SE of Escondido and 6 miles SW of Ramona. Station mark is on the highest point of a 15 foot boulder, about 100 feet E of an 80 foot lookout tower.

Six Recovered Survey Marks

These six recovered marks represent three different types of brass discs and a physical location called an Intersection Station. The disks are differentiated by the stamping and symbols used. You will find the type of disk stamped in the outer ring of text along with the issuing agency.

  • Triangulation Station (this disc also bears the Triangle symbol)

  • Reference Mark

  • Azimuth Mark

When the Reference and Azimuth discs are set in place, they are aligned so that the arrow points directly toward the Station disc. This is done in order to help locate the station during subsequent surveys and can be useful if the station disc has been damaged or removed. Reference marks are always going to be within line-of-sight to the Station and generally placed at 90º angles to the Station if possible, this facilitates triangulating the station location. Since 1921, a Triangulation Station required a minimum of two Reference Marks.

The final picture of the parking lot near the water tank (and towers out of frame to the left) is the "Cobble Back Mount Lot", an Intersection Station. An Intersection Station is a survey point whose position is determined by directions observed from two or more known stations.

During a Station Recovery completed in 1960 by the U.S. Coast and Geodetic Survey (USC&GS), the surveyors failed to find the original Azimuth Mark (PID: CF1784) and noted that a concrete water reservoir had been built on the top of the boulder blocking line-of-sight between Reference Mark 2 and the Station Disc. As a result of these findings, a new reference mark (RM 3) and Azimuth Mark were established and set.

Locating the Azimuth Mark

Even though the 1960 recovery reported the Azimuth missing, I spent about an hour scouring the location of the original Azimuth Mark anyway (even if the notes say the mark is missing, I still want to verify that myself). Azimuth Marks are usually located at least a half-mile or more away from the station, with just a compass heading (no exact latitude/longitude coordinates) so you really need to sharpen your orienteering skills to locate these. Because the Azimuth was not located on the mountain, I made that recovery on December 21, 2020, and I found it after scrambling around in the brush for a while. Believe it or not, I came upon it from the backside and I found the disc in the boulder BEFORE I saw the witness sign!

DX5039 Mt Woodson Lookout Tower No Longer Exists

The original Woodson Lookout Tower from 1936

According to the Forest Fire Lookout Association, The original lookout was likely constructed by Civilian Conservation Corps crews in 1936. The 80-foot tower would have been the tallest known in Southern California at the time.

It was replaced in 1950 by a more modern tower which was subsequently lost in a fire. The site notes the last lookout tower on Woodson had been demolished or removed by 1991.

Of course today, the summit is dotted with a variety of radio and communication towers, including two that sit on the spot of the original tower. There are still Geocachers who claim "finding the tower on Woodson in good condition" mistaking the current radio towers for the old lookout.

The original Lookout Cabin as and boulder with Station disc viewed from the Cobble Back Mount Lot

Mt Woodson Eccentric Station

The 7th and final recovery I made was the Mt Woodson Eccentric (ECC) station, PID: DX5029. This one was located on a boulder over a quarter of a mile below the summit, not too far off the paved road.

This is a California Division of Highways (now Caltrans) 2" brass disc, stamped as shown. This was really kind of a pain to find as it is smaller and the color blended in well with the boulder it was mounted on. Oh, and yeah, I was standing ON TOP OF IT while using my binoculars to examine nearby boulders looking for it! 😂

In the surveying world, an Eccentric station is defined as a survey point over which an instrument is centered and which is not positioned in a vertical line with the station it is representing. Not being a surveyor, I probably don't get all the nuances of that, but as a hobbyist scavenger hunter, the ECC marks are usually different and therefore cool 😉 When I hiked Woodson Mountain on January 1, 2021, I had two primary missions:

  • Bag my first peak in the San Diego Six-Pack of Peaks Challenge 2021

  • Recover all the Survey Marks for the Woodson Station

As I hit the summit, I kept going down Mt Woodson Road to this eccentric mark first. Once I had recovered it, I headed back up to the main boulder to find the station and reference markers.

In the excitement of scrambling up the summit boulder and easily finding the Station and two Reference Marks, I missed Reference Mark 3! 🙄 When I got home I realized that I missed it, I knew I had to go back. Today I completed my original mission by returning to the mountain and officially recovering Reference Mark 3! 7 of 9 marks recovered with the 2 "lost" marks clearly NOT recoverable.

Disclaimer: Survey markers may be located on private property, please respect the landowner’s privacy and property rights while searching for markers. Additionally, many markers are located along active roadways, use common sense, take appropriate safety precautions, and exercise due care to avoid potential injury. If you choose to search for survey marks it is at your own risk. Please do not disturb or remove Survey Markers!

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