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  • Writer's pictureDale Hill

May 2021 'Drive-By' Survey Marks

Updated: Jun 3, 2021

While most of my recoveries are on hikes or specific outings where I'm looking for one or more specific markers, there are the ones that are just 'along the road'. I call these 'Drive-By' recoveries because I'm driving with my GAIA GPS USGS Topo map in 'follow' mode and I can see the benchmark notations along my route. It's mostly about keeping your eyes open and paying attention.

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!

May was my most prolific month of Drive-By Recoveries to date, many of these are noted on the USGS Topo Map with an "X" and the initials "BM" with the elevation for the mark, Some, like the string of SDPR marks, popped up on the NGS Data Explorer when I was researching GPS on Bench Marks priorities. For every one of these I find, there are probably at least three that I couldn't locate. Many of the survey marks that are right along the roads end up being destroyed or covered during road widening or resurfacing projects. Technically, contractors are required to identify all survey marks that will be disturbed or destroyed by their work and submit that information to the NGS so the marks can be reset, but that doesn't always happen.

Since there are so many recoveries this month, the Quick List below is hyperlinked to each individual mark so you can jump right to a specific one, if there are multiple marks in a gallery, the link provided is to the grouping.

I finished up May with a total of 359 survey marks in my database, I take at least two pictures of each mark, a close-up (with the engraving highlighted if possible) and one from eye-level that gives a general idea of the immediate area of where the mark is located, this may or may not include the horizon or other specific identifiable landmarks.

Quick List

  1. DX5040: HIGHLAND 1975 (Ramona, CA)

  2. CF0829: HIGHLAND RM NO 1 1975 (Ramona, CA)

  3. DX5041: HIGHLAND AZIMUTH 1975 (Ramona, CA)

  4. EV9238: PITS 1982 (Angelus Oaks, CA)

  5. CS6704: PITS RM NO 2 1982 (Angelus Oaks, CA)

  6. DX4988: YAP (Ranchita, CA)

  7. CF0501: YAP PICTURE POINT (Ranchita, CA)

  8. AI4550: SY 64 1968 (Santa Ysabel, CA)

  9. AI4547: SDPR 13 1995 (Borrego Springs, CA)

  10. AI4548: SDPR 14 1995 (Borrego Springs, CA)

  11. AI4549: SDPR 15 1995 (Borrego Springs, CA)

  12. AF9887: SDPR 16 1995 (Borrego Springs, CA)

  13. AI4551: SDPR 17 1995 (Borrego Springs, CA)

  14. DX0462: ZONE 6 TRV STA CL 1 1963 (Borrego Springs, CA)

  15. DX0366: ZONE 6 TRV STA BOR 11 1963 (Borrego Springs, CA)

  16. AI4557: SY 42 1968 (Santa Ysabel, CA)

  17. DX0253: W 521 1956 (Santa Ysabel, CA)

  18. DX0207: M 580 1939 (Julian, CA)

  19. NE CORNER, SEC. 11, TOWNSHIP 13S, RANGE 5E, SBBM (Julian, CA)

  20. NE CORNER, SEC. 24, TOWNSHIP 13S, RANGE 5E, SBBM (Julian, CA)

  21. DX0174: BOR 39 1969 (Julian, CA)

  22. DX0223: U 580 1939 (Julian, CA)

  23. AF9886: MON 37 ECC 1995 (Santa Ysabel, CA)

  24. DX0388: SY 99 1969 (Santa Ysabel, CA)

  25. SYFP 1 2014 (Santa Ysabel, CA)

  26. DX0411: Z 570 1939 (Warner Springs, CA)

  27. DX0461: 14 JRH 1957 538 FEET (Borrego Springs, CA)

  28. DX3541: K 1326 1978 (Borrego Springs, CA)

  29. DX3539: M 1326 1978 (Borrego Springs, CA)

May 14, 2021 - Highland Valley Road, Ramona, CA


The Highland Azimuth Mark was technically the "Drive-By", located just off of Highland Valley Road. Azimuth marks are often some of the more difficult ones to find as they don't necessarily have specific coordinates or distances from their main station. Finding an Azimuth Mark first makes it easier to locate the station disc because the arrow on the disc points directly at the station (similar to a reference mark).

The exact distance between Azimuth and Station is rarely provided, but in this case, the hill where the station was located wasn't too far away so I headed over and bagged it and Reference Mark No 1.

May 15, 2021 - SR 38, Angelus Oaks, CA

EV9238: PITS & CS6704: PITS RM 2

I was on my way to hike San Gorgonio and last night had identified several survey marks that were along my drive via SR 38. My plan was to look for them after I completed my hike since I had a full day planned and I wanted to get on the trail as quickly as possible. As it turned out, I needed to make a pit-stop anyway 🤷🏻‍♂️🤫 so I took advantage of the need to stop and, after taking care of necessities, easily found the station disc.

Reference Mark 2 was a little trickier to find as the concrete monument that it was mounted in was on the backside of a sandy slope and almost completely covered in dirt. I caught a glimpse of some concrete sticking out of the dirt, went down the slope, and uncovered the monument and marker!

May 22, 2021 - SD County Road S22, Borrego Springs, CA

San Diego/Imperial County Sign Route S22 (originally defined in 1968) runs East-West beginning at San Felipe Road (S2) and terminating at SR 86 near the eastern shore of the Salton Sea and covers 47.51 miles. S22 is also part of the De Anza National Historic Trail. Along the way, it picks up several different names, I've included the "local name" in parenthesis in the subheading for each mark.

DX4988: YAP & CF0501 YAP PICTURE POINT (S22 - Montezuma Valley Road)

Triangulation Station YAP is a U.S. Army Corps of Engineers disc set just a few feet back from the shoulder of Montezuma Valley Road with a witness stake nearby. With all the desert hikes I've done, I can't begin to count how many times I've driven right by this mark! It has two reference objects listed on the NGS datasheet, I couldn't find the first, a USACE Reference Mark disc, my guess is that the monument was destroyed while grading the shoulder.

The second reference object is an intersection station formed at the centerline of the cross streets, Montezuma Valley Road (E-W), Wilson Road (S), and Via Oak Grove Lane (N). This station is called the "Yap Picture Point" and is basically just a spot on the road. I made a cursory look to see if there was any kind of nail and tag in the centerline, but I didn't see one. I've added a target image to my photos to approximate the location of the mark.

AI4550: SY 64 1968 (S22 - Montezuma Valley Road)

SY 64 was an easy-peasy recovery, it's right across the street from Yap! When I was taking pictures of the "Picture Point" I noticed a "t-bar" fence post that wasn't on the fence line, (these are often used as witness stakes) so I went over to explore, lo-and-behold, another recovery! 😉 

The "SDPR Line" (S22 - Montezuma-Borrego Highway)

This collection of marks was a really cool recovery, I actually recovered seven consecutively numbered survey marks SDPR-11 through SDPR-17. There are only five of them in this gallery as the other two were GPS on Bench Marks priorities and will be listed in my May 2021 GPSonBM post. All of these marks were set by the California Department of Transportation in 1995.

DX0462: ZONE 6 TRV STA CL 1 1963 (S22 - Palm Canyon Drive)

Prior to today, I'd only found one disc set by the San Diego County Surveyor that was stamped California Coordinate System Zone 6, and that was a triangulation station at Boucher Hill on Palomar Mountain. Today I recovered three Zone 6 Traverse Stations!

Traverse networks involve placing survey stations along a line or path of travel and then using the previously surveyed points as a base for observing the next point. There are a few different types, closed, open, and compound, that all deal with the starting and ending points of the network. A traverse network can have control points that form a closed-loop, follow a line, or a combination of the two connected together. According to what I read, they are more accurate than Triangulation Networks 🤷🏻‍♂️but I'm not a surveyor 😉

DX0366: ZONE 6 TRV STA BOR 11 1963 (Borrego Valley Road)

The other two traverse stations were both on Borrego Valley Road BOR 11 & 12. BOR 12 is on the GPS on Bench Marks priority list (and will be detailed in that post), while I was researching that one, I saw that BOR 11 was just a couple blocks down the road and an easy find.

May 23, 2021 - SR 79, Santa Ysabel, CA

AI4557: SY 42 1968

Driving back from our Palm Mesa High Point hike earlier today, I had my GAIA GPS up on my phone in nav mode, with the USGS Topo map as the active map layer. I really wasn't paying attention because I was tired from the hike and it was getting late, but Alberto piped up and said "there's a benchmark!" sure enough, he'd seen it on the topo so I turned around and pulled off the road, this particular mark was on a cut bank above the road, just over a fence, the witness stake clearly visible.

May 26, 2021 - Destination: Blair Valley

I had planned a survey mark scavenger hunt outing in Blair Valley for today that started off with two GPS on Bench Marks recoveries en route to Blair Valley. The road to get there is prime territory for Drive-By Recoveries and there are lots of survey marks along SR 78 as it goes through Santa Ysabel, Julian, and drops down in Anza-Borrego Desert State Park to Scissors Crossing. Once headed East onto the Great Overland Stage Route (S2) there is the potential for lots of Public Land Survey System (PLSS) corner marks simply due to the orientation of the S2 in relation to the PLSS Grid (this is a bonus in addition to the usual benchmarks and vertical control marks on the route!)

DX0253: W 521 1956 (SR 78 - Santa Ysabel)

I have actually stopped and looked for this mark several times on my way through Santa Ysabel, it's marked by the standard benchmark notation on my TOPO map and its apparent location on the map is right next to a turnout where there's an emergency call box, I'd searched the East side of the road around the turnout pretty thoroughly, today I just leaned against the truck and examined the terrain on the other side of the road. Directly across the road was a big rock outcrop, I crossed to the low side of it, and BAM! just like that, there was the mark! 🤦🏻‍♂️

Potential Survey Mark Locations. Generally speaking, survey marks should be mounted in the most stable material possible. Benchmarks are typically mounted in rock outcroppings where possible. There's a preferred hierarchy of "best to not-so-good" mounting surfaces: rock outcropping, boulder, then a concrete monument. In order to provide a reliable survey point that will stand the test of time, they need to be mounted in the most stable means available. It's ALWAYS a good practice to look for a low, flat rock sticking out of the ground first (unless you know it's mounted in some other way according to a datasheet).

DX0207: M 580 1939 (SR 78 - Julian)

There are a lot of potential benchmarks along the section of SR 78 going through Julian (Banner Grade), the tough part is that Banner Grade is a twisty, narrow, mountain road. I have passed by many possible recoveries simply because there was not a safe place to pull completely off the road and park while I looked for the mark.

This was a notable exception to that rule, as there is a wide dirt shoulder near the "green rock", it is also right before a gated driveway on the West side of the road. At first, the mark just blended in with the garishly painted rock (the mark was dirty and had paint on it as well) so it was hard to see. I have only found two vertically mounted benchmarks previously, and both of those were on buildings, so I'm not usually looking up for marks. However, once I saw it, brushed it off, and added some chalk, it stood out well enough.

The Public Land Survey System (PLSS)

I found two section corners today, both were an easy walk from the roadside. It's really remarkable all the different ways that section corners can be monumented (marked), I've found several in ABDSP that are marked with engraved pipe caps such as the ones I found today. Locating section corners, quarter-corners, or other line marks is actually pretty easy, it just takes patience and knowledge of the PLSS grid. I have described this in other posts, but I'll do a quick recap and provide an image to illustrate my explanation.

Finding Section Corners on the USGS Topo Map

Public Land Survey System (PLSS). Most of the United States is divided up into a neat grid of Townships, each township is roughly 36 square miles (6 miles x 6 miles) the lines that make up the townships are called township lines (which run East-West) and range lines (which run North-South), these townships are further segregated into Sections which are 1 square mile each, each township contains 36 sections. Sections are often further divided into individual lots. There are a lot of different terms that apply to the PLSS, the link I provided above is a good starting place to learn the basics about the grid system. I put together the image below to show how I locate corner marks and added some information to identify key points, (I found last year).

NE CORNER, SEC. 11, TOWNSHIP 13S, RANGE 5E, SBBM 1954 (S2 - Great Overland Stage Route)

When I'm looking for Drive-By Benchmarks, I watch my map for the appropriate "X" symbol with the "BM" and elevation reading. Looking for Corners is much more predictable, I just need to look for the red grid lines and the red "+" cross or plus sign marks. If a plus sign is in bold, then there is a greater chance that there is a formal survey marker at that corner. Not all corners have an obvious mark, but in the desert, once you're in the general vicinity it's pretty easy to see a pipe cap, rock cairn, witness stake, etc.

There are multiple ways to verbally identify corners, I've been leaning towards using a 'mostly' legal description (legal as in the sense of what is used in deeds and other legal property descriptions). For consistency, I will usually pick the northeast corner of a section and use that as my primary point. So in the mark above, I've identified the Northeast Corner of Section 11 that is located in Township 13 South, Range 5 East. The "SBBM" stands for the San Bernardino Base and Meridian or principal meridian, the reference point for the PLSS in Southern California. (check out this Wikipedia link to learn more about Principal and Guide Meridians).

In this case, T13S R5E refers to a spot 13 Townships South (of the Baseline), and 5 East (of the Principal Meridian - SBBM). Another way to think of this is that this township is approximately 78 miles South, and about 30 miles East of the Initial Point for the SBBM.

NE CORNER, SEC. 24, TOWNSHIP 13S, RANGE 5E, SBBM 1946 (S2 - Great Overland Stage Route)

This is the second corner I found today and it was just across the road from the Blair Valley Range Station, it's pretty cool because:

  1. It is a General Land Office disc (I like those!)

  2. It is a Township Quarter-Corner, meaning not only does it mark a single Section, but it also marks the point that would divide the larger Township into four quarters. You can see this by the stamping on the mark, it includes reference to two different Range Lines, R5E and R6E 😉

DX0174: BOR 39 1969 (SR 78 - Julian)

This was the first of two recoveries on my way home from Blair Valley, this one was on westbound 78, not too far past the historical monument at Scissors Crossing. Again, an easy find when you know what to look for, fence stakes that are not on the fenceline area a good indication of a witness stake and a marker, even when there is no symbol on the TOPO map.

DX0223: U 580 1939 (SR 78, Julian)

Overall, I'd had a pretty good day with recoveries so I told myself only one more Drive-By then I'd turn off my map and just get home 🤣 This was the next benchmark shown on my map, it was on the right side of the road with a stated elevation of 2,560. I pulled off the road right by the "X" on the map, walked a few feet towards the fence, and easily spotted the mark! A nice way to end up the day's hunting.

May 28, 2021 - Reconnaissance Mission to Santa Ysabel, CA (SR 79)

I had seen images of a unique survey mark online while researching different trails to hike in Santa Ysabel. Once my "Grandpa" duties were done for the day, and my little granddaughter went home, I headed out to Recon some potential trailheads. Of course, on the way home I HAD to stop and pick off a few Drive-Bys! 😂

AF9886: MON 37 ECC 1995

Back in January, I had located a pipe cap marker designated MON 37, it was a boundary marker placed by the General Land Office (GLO) that went back to 1915. That day was also the first time I found one of the old "C" Block Right of Way Marks placed by the California Division of Highways to mark old highways. When I got home and was researching those marks, I noticed that there was an Eccentric station for MON 37 not too far away, so I tagged it with a waypoint and decided to look for it the next time I was out that way. Well, today was the day! I also found another C Block stone nearby, but it's identical to the two I've previously documented, so I skipped it as an official recovery.

DX0388: SY 99 1969 (SR 79)

At one point earlier this year, I had researched and plotted a bunch of survey marks and boundary marks that appeared to be easily accessible and potential Drive-Bys along SR 79 in Santa Ysabel. My first thought was that I'd dedicate a scavenger hunt day just to all the marks in a few-mile stretch of the 79 (much like I've done in previous cases like Ortega Highway, or those in the Shadow of North Peak in Cuyamaca Rancho State Park) but it just didn't work out, so they're list as Drive-Bys as I find them. This was one of the marks on that initial list.

SYFP 1 2014 (SR 79)

This particular mark was a surprise find, it's not currently listed in the NGS database but it's almost in the exact location of a mark that is listed but is no longer there (DX0387: SY 18 1968). SY 18 was supposed to be mounted at the NW corner of the bridge. Specifically, on the Santa Ysabel Creek Bridge, West Abutment. I found this one instead on the SW corner of the West Abutment, apparently, the bridge was rebuilt in 2014 and the original survey mark was lost/destroyed.

May 31, 2021 - Destination Borrego Badlands, Borrego Springs, CA

I had planned an easy day of survey mark scavenger hunting and desert hiking acclimation in the Borrego Badlands, the full trip report can be found here [link will be active once the report is complete]. Naturally, as I drove through Borrego Springs I kept my eyes open for potential recoveries.

DX0411: Z 570 1939 (S2 - San Felipe Valley Road)

This seemed like an easy Drive-By as I turned off SR 79 onto the S2, San Felipe Valley Road, the Benchmark symbol on the TOPO map was just after the turn and there was a good place to pull off the road. It was located just an embankment near some power poles.

DX0461: 14 JRH 1957 538 FEET

I just happen to spot the witness sign for this one when I stopped at the intersection of Borrego Valley Road and Palm Canyon Road (S22). Interestingly enough, I had a few other nearby recoveries (CL 1 and BOR 11 listed above) just over a week ago.

I had driven by this mark a few times and never noticed it! There was supposed to be a survey mark labeled "SCHOOL" almost in the same spot, but previous reports indicated that it had been either destroyed or covered up when the road was widened. Since I knew that it wasn't there, I really didn't pay much mind to that corner of the intersection, but today it caught my eye.

DX3541: K 1326 1978

Neither of the next two recoveries was annotated on the TOPO map with the traditional Benchmark symbol, basically because they are Vertical Control Marks! Thankfully, they each had standard witness signs nearby that made them easy to spot! This one was at the turnoff for the Ella Wash Jeep Road, just a short distance before my turnoff for the jeep road that led to the Aroyo Salado Primitive Camp. I had actually pulled off here thinking it was my turn, while I was checking my maps, I noticed the witness sign off to the side of the jeep road.

DX3539: M 1326 1978

I had actually known about this particular mark since the day we did Villager Peak last year, it's located at the unofficial trailhead for the Villager Peak Trail, at the dirt parking area just off the Borrego-Salton Seaway (S22). When I first spotted it, it was marked with the typical witness sign, but the mark was below grade in a 6-inch PVC pipe with a pipe cap on it. Back then I tried to unscrew the cap, but without a pipe wrench, it wasn't budging. Now I just keep an adjustable pipe wrench in the truck for situations like this. Of course, today when I stopped by, the cover was loose and I didn't need the wrench! 🙄

Phew! What a month! It never ceases to amaze me at the variety of marks I find along the roadside. Twenty-nine Drive-Bys and I still have four GPS on Bench Marks recoveries to write up! I had a great mix of issuing agencies and types of marks this month and each one seems to have its own story 😊 As I mentioned at the start of this post, my database of recoveries is up to 359. I'm not sure what June will bring, as I'm currently sidelined with an ACL injury, but you just never know. One thing for sure is that I'll stay curious and keep searching!

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