Solitude Peak Survey – New WA Top 100 Peak

Solitude Peak Survey

June 30, 2023

4:30am – 7:30pm, 17 miles

Results: Summit elevation 8,406.0ft +/-0.1ft,  prominence 414.1ft +/-0.2ft , now #74 on WA hundred highest list

I discovered that an officially unnamed, rarely-climbed peak deep in the North Cascades is actually tall enough and prominent enough to be among Washington’s hundred highest peaks. I’ve recently been trying to determine the most accurate possible list of the hundred highest peaks in Washington. To qualify for the list a peak must have at least 400ft of prominence, the height of the peak above the saddle connecting it to a higher peak. This ensures that small bumps on a ridge don’t count as separate peaks. The peak must stick out enough by itself to qualify.

The original list was compiled using the USGS quad maps, but those maps sometimes have errors, and the precision is given by 40ft contour intervals. Some peaks are close to qualifying for the list, but either the summit was never directly surveyed or the saddles around the peak were never directly surveyed. In these cases the quad is not accurate enough to determine if the peak qualifies.

There is beginning to be Lidar coverage of peaks in Washington, and this is a good tool to figure out the true hundred highest peaks. However, many peaks are not yet covered by Lidar. SRTM (satellite-based elevation measurements) cover all of Washington, but the error in measurements can be very high. For peaks or saddles not directly surveyed on the quad and not covered by Lidar the only definitive way to find if they qualify for the list is with a ground survey.

One peak that intrigued me was Solitude Peak. It’s officially unnamed and is in the Chilliwack area of the North Cascades between Mt. Spickard and Easy Mox. The summit of Solitude Peak was surveyed on the Mount Spickard O48121h2 1:24,000 quad at 8,405ft and the saddle determining the prominence is between the 8000ft and 8040ft contours. This means it is tall enough to be a top 100 peak, but the prominence is not known accurately enough to say if it qualifies. Based on the quad the saddle could either be exactly 8000ft, giving a prominence of 405ft and making the peak qualify, or the saddle could be as high as 8040ft, giving a prominence of 365ft and disqualifying the peak. The only way to know for sure in this case was a ground survey.

I own my own mechanical theodolite that I’ve been using to measure summit elevations on previous survey trips. The theodolite measures angles between points, and I can use known distances and trigonometry to find relative heights. In theory if I brought the theodolite to the saddle and measured the angle to the summit I could find the relative height, which would be the prominence. The problem is if a peak is not sharp enough the true summit is often not actually visible from the saddle.

I suspected this would be the case for Solitude. I’d been to that saddle before (climbing Mt. Spickard), but had never climbed Solitude and couldn’t remember if the summit was visible from the saddle. I could instead take measurements from the saddle to other surveyed peaks nearby and figure out the saddle elevation, then use that to figure out prominence. This was a viable option. But I had an alternative option also that would not involve carrying in the heavy theodolite and surveying tripod setup.

I’d just acquired a survey-grade differential GPS unit capable of 1 inch vertical accuracy if a one-hour measurement was taken (Spectra Promark 220 with Ashtech antenna). I’d used this kind of unit before, borrowed from Compass Data, for discovering/surveying the country highpoints of Saudi Arabia, Togo, Gambia, Guinea, Guinea-Bissau, and Ivory Coast. The unit I have now has a big antenna to account for multipath errors and a rover unit that looks like a large handheld GPS. How it works is I mount the antenna on a tripod so a pole below the antenna touches the point I want to survey.

The antenna is connected to the rover unit with a cable and I start taking measurements. This unit is GNSS, meaning it has access to many more satellites than a standard handheld GPS unit. This helps increase accuracy. The longer I take measurements the more accurate the result. It’s called a differential GPS because I compare the measurements taken by the rover unit to those taken by nearby base stations. Base stations are locations where a GPS unit has sat stationary for years, so its position is known with very high accuracy.

If I compare my measurements to those of nearby base stations I can correct for atmospheric distortions which affect accuracy. This assumes the atmospheric conditions at the base stations are similar to those where I take the measurement. This means I need to post process my measurements afterwards, and I need to wait for enough data to be collected by the base stations to do the post processing.

The US National Oceanic and Atmospheric Administration (NOAA) has an online tool to post process measurements (https://geodesy.noaa.gov/OPUS/). You just need to wait 24-36 hours after they were taken, then convert them to the correct format, upload them and you get results within a few minutes with 1-sigma error bounds.

The rule of thumb is in an area with a clear view of the sky you can get about 3 inch vertical accuracy in 20 minutes and 1 inch vertical accuracy after an hour of taking measurements. I’ve talked to surveyor engineers from Compass Data (the company who surveyed Denali) and they say the surveying standard is a one-hour measurement. That’s what I did surveying in west africa and I got good results.

So my plan was to take a one hour measurement at the summit of Solitude Peak, then a one hour measurement at the saddle. The surveyed points on the quad can still have error up to a few feet (as I’ve verified comparing surveyed points to recent Lidar data in other areas of Washington), and in this case a few feet could make the difference between the peak qualifying or not. So it was important that I got elevation measurements to the nearest inch of both the saddle and the summit.

For the climb up Solitude I found a good trip report on nwhikers from b00 from 2015 that it was a 3rd class scramble from the Solitude-Spickard col. To approach this area I originally planned to use my zodiac boat on Ross Lake to Little Beaver and bushwhack up Perry creek. I’ve used this approach three times in the past year to access the peaks in that area, and I know it well. But my boat motor is still in the shop for repairs, so that wouldn’t work. I also ideally wanted to do the trip as a day trip to avoid dealing with getting a permit from north cascades national park. So I decided to do the standard Depot Creek approach as a day trip.

I’d previously done this approach with Steven in 2018 bagging all the Bulgers in that area. I saw Eric Eames had just posted on nwhikers that he’d driven up the approach road all the way to the start of the depot creek trail the previous weekend. That was great news.

Thursday night I drove up Chiliwack Lake road to the south end of the lake. The road started deteriorating with deep drainage ditches after I left the lake. I have a truck with good clearance, but the hitch sticks out enough that it started scratching on some ditches. So by 11pm I parked at a nice pullout 1 mile from the start of the trail.

I was up and moving by 4:30am Friday, and it was just light enough to not need the headlamp. I soon reached the unmarked trail, and followed it across the border to the North Cascades trailhead kiosk. I signed in and continued up.

Amazingly the first 1/2 mile of trail had been recently logged out, and little orange markers put on the trees. Then I hit a big patch of blowdowns for a quarter mile. After that I could generally follow the climbers trail, though it was a little overgrown in places.

I soon reached the waterfall and used the handline to pull myself up the slippery slabs. I then hiked steeply up to reach the flat basin at 5000ft. I kept following the trail and cairns until I hit Lake Ouzel where I stopped to eat.

Above me loomed Solitude Peak. It has a huge 1200ft tall west face facing the lake, and that would be a very challenging way up. Luckily I knew the easiest way was only 3rd class. There was a lot less snow this time than in mid July 2018 when I had been there before. I guess there was a very hot and dry spring in Washington.

I continued up the drainage heading towards Silver Lake, then traversed right at 6800ft below Mt. Spickard. I hit snow around 7000ft and it looked continuous up to the Solitude-Spickard saddle, so I put crampons on there. It was still morning and half the snowfield hadn’t seen sun yet, so it was pretty icy. I continued up carefully with my whippet and my hiking boots. I think my evo nepals would have been more appropriate, but I was trying to save weight so just used the same flexible hiking boots as on the hike in.

As I got higher I was careful to kick deep solid steps, which took 5-10 kicks each. I eventually made it up to the ridge a bit northeast of the true saddle. There I got a good view of Solitude. It looked steep, but the right skyline ridge seemed doable. I took off crampons and traversed to the true saddle, which had a small bivy site cleared out nearby. I crossed the low-angle soft snowfield then gained the base of Solitude.

At the edge of the snow I ditched my poles and crampons and started scrambling up. In general I followed the north ridge. I started out on the right side but eventually switched over to the left. The rock was very loose, and felt like class 3/4. It was slightly exposed in a few places, but maybe I didn’t take the easiest line.

I soon popped out on top by 11:15am, and I was delighted there were no false summits. There was a small cairn on a flat boulder, then to the west was the true summit rock, as I verified with my 5x sight level. I quickly got out my small surveying tripod, mounted the antenna on the summit, and hooked up the GPS. I couldn’t mount it exactly on the summit but I had a tape measure and measured the vertical distance between the bottom of the antenna rod and the summit.

On the rover unit I entered in the height of the antenna above the survey point (antenna rod length minus the distance I just measured), then started logging data. I then had an hour to sit and admire the view. I rarely spend this long on a summit, and it was kind of nice. I tried identifying all the peaks around me, then verified my guesses using the peakfinder app on my phone. I was the only person in probably a 10-mile radius, so Solitude Peak seemed like an appropriate name.

I had also brought my Garmin 62s handheld gps to try to get some extra data. The accuracy is definitely not as good as the differential gps, but it couldn’t hurt to take more measurements for comparison. I turned it on at the summit, but it took a long time to stabilize, and after the hour it still hadn’t stabilized, so I didn’t get any usable data from it. I think if I had turned it on at the trailhead and kept it on the whole morning it would have stabilized more quickly.

After the hour was up I saved the data to the device and an external SD card, then packed up. Interestingly, I noticed the saddle was actually visible from the very summit. Solitude Peak is kind of unique since the ridge from the saddle to the peak kind of wraps around so there isn’t anything obstructing the view between saddle and top, and the part of the peak facing the saddle is a big cliff. So a theodolite measurement would have worked after all. I should have used my sight level to sight the saddle from the summit, but for some reason didn’t think of that at the time since it wasn’t in my original survey plan.

I made the fun scramble down to the edge of the snow and collected my stashed gear. I then noticed that the intermediate saddle at the base of Solitude was a deep, sharp notch that maybe was lower than the other saddle. If that was the case then it would determine the prominence. It was tough to tell by eye, and there was a snowfield obstructing the view between saddles, so I couldn’t use my sight level. So I decided to just take another measurement there.

I mounted the antenna and tripod on the rocks on the low point of the saddle and took another one hour measurement. This time my view was a little more obstructed. I killed some time doing the physical therapy exercises the doctor prescribed for my shoulder (I had dislocated it in a fall on Mt Everest a few months earlier). Then I packed up and headed over to the main saddle.

I again mounted the setup at the low point of the saddle and started logging data. I looked up and could clearly see the summit, so I decided to take a few angle measurements with my sight levels. I brought a 1x and a 5x sight level. Each one can measure angles to the nearest 0.1 degree with a vernier scale. Though there is error in aligning the bubble perfectly without a solid tripod and error in pointing perfectly at the summit. So, the true accuracy is not quite as good as my theodolite with 30x magnification and 20 arcsecond accuracy. And ideally I would have backsighted from summit to saddle. But, these would still give independent measurements to increase confidence in the final differential gps measurement.

I also set the Garmin 62s at the saddle and it stabilized very well at 7992ft. This also gave another good independent measurement, though it had much higher error than the differential GPS. I considered going up and tagging Spickard while the measurements were being taken. But I was worried that some little thing might go wrong with the device (like the wind or a marmot knocking over the antenna), and if I weren’t there to correct it I’d get useless data. So I stayed there and kept monitoring the data collection every 5 minutes.

After the hour was up I saved the data, backed it all up on the SD card and two phones, then started heading down. Luckily now the snow had softened considerably. I scrambled down to the snowfield then put my crampons on. The top was still a bit firm but I was able to use my previously-kicked steps to downclimb. Lower down I kicked new steps, and eventually made it down to rock. I took off my crampons, then traversed back to the Spickard-Custer saddle. From there I had fun and fast boot skiing most of the way down to Lake Ouzel.

I hiked back down from the lake, then followed some cairns. I met a group of climbers heading up to go for a bunch of Bulger peaks in there. I told them Solitude was likely a hundred highest peak, though I still needed to process the results to be certain.

I made good time hiking out, and made it back to the truck by 7:30pm. Two more groups were heading in, and indeed this long weekend is a great time to bag all the Bulger peaks back in there. I drove out carefully and made it back home by 1am.

After waiting 36 hours I was able to upload the data to the NOAA OPUS site for post processing. This gave me orthometric elevations using the standard NAVD88 datum. This datum is a model of the earth’s surface used as a standard reference for calculating elevations, kind of like defining a local mean sea level height. The quads were surveyed using an older datum, though, NGVD29. This older datum is traditionally what is used for peaks in washington so they are consistent with the quads. So I next converted the measurement to orthometric height in the NGVD29 datum using another online tool from NOAA called NCAT (National Geodetic Survey Coordinate Conversion and Transformation Tool https://geodesy.noaa.gov/NCAT/). This gave me my final elevations.

I found the summit of Solitude Peak is 8,406.0ft +/-0.1ft and the saddle elevation is 7,991.9ft +/-0.1ft. This means the prominence is 414.1ft +/-0.2ft. Thus, Solitude Peak qualifies as a Washington hundred highest peak because its prominence is above 400ft and it is of sufficient height.

My measurements from my sight levels put the prominence at 410ft – 424ft, so this increases confidence in the results. My Garmin 62s put the saddle elevation at 7991ft, which, when compared to the surveyed height on the quad, would put the prominence at 418ft (with unknown error bounds from the Garmin 62s measurement). This also increases confidence in the result that the prominence is above 400ft.

Note: the Bulger list is slightly different than the strict Washington Hundred Highest list. The Bulger list is historical and doesn’t change. The strict Washington Hundred Highest list can be updated as more accurate surveys are conducted.

Link to raw measurements: https://docs.google.com/spreadsheets/d/1FTE4pokewgpSGtnvLOh0KVi9szEpbTDH7pdslhKOLfU/edit?usp=sharing

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