Introduction

West Eolus is perhaps the most quintessential San Juan 13er. Remote, technical, and obscure, it is hard to think of more fitting peak to be the only remaining soft ranked 13er. Due to it's high elevation, it is also a candidate for both the Bi and Tri-Centennial lists.

LiDAR data found that West Eolus had 299.4751 feet of prominence (NAVD88). Eric Gilbertson et. al. have found that LiDAR is accurate to ±1.7 feet on rocky summits like West Eolus. If we assume that same uncertainty for the saddle, the LiDAR data was inconclusive with a 66.56% chance that West Eolus was unranked and a 33.44% chance it was ranked. Further, careful analysis of the LiDAR point cloud demonstrated that LiDAR very likely missed the small summit atop West Eolus.

Given this ambiguity, when Eric Gilbertson lent us his Trimble DA2 dGNSS antenna (thanks Eric!), Ben Loftin and I jumped on the chance to hopefully resolve West Eolus's true status. The only problem was that neither of us felt 100% sure we could cleanly climb the 5.7 offwidth crux. We contacted every technical peak bagger you can think of: BoggyB, Furthermore, Blazintoes, Alex Henes, etc. but alas no one was able to make a trip work on such short notice. Ultimately, we decided to borrow an aid ladder, a #4 cam ,and #5 cam from John Kirk (thanks John!) and I would try to aid the crux.

The Trip

Ben and I met near Purgatory Friday night and exchanged gear. He would ride the train in from Durango with all the heavy climbing gear while I would hike in from Purgatory Flats and meet him at Needleton. On Saturday morning, I tested the antenna and began my hike in at 7am. I'm rather fond of the Purgatory trail so I didn't mind the extra mileage. I arrived at Needleton in 3 hours and 20 minute and waited 10 minutes until Ben arrived on the train. Perfect timing!

After dividing the rope and rack, we charged up the Needle creek trail. After about two hours we started to climb north up into the high basin below West Eolus. The mileage was starting to catch up to me and Ben graciously took the rack from me halfway up.

We set up camp near a small stream around 12,600 ft and began to climb up to the Mt. Eolus-West Eolus saddle. To our astonishment, we saw two Elk and and a calf utilizing the high approach ledge around 13,400!

We traversed across the access ledge to the first pitch of climbing and I easily dispatched P1. After belaying Ben up I started on P2, itching for revenge on the off width. To my dismay I was still unable to crack the crux and burned 30-60 minutes on a few moves. Ben, patient as ever, asked if he could give it a shot. Ben took the lead (his 1st lead climb EVER I should add!) and waltzed right up P2. I followed and hauled up our packs. I once again took the lead on P3 and made quick work of the chimney until I reached the final choke stone pullover. My arms were so tired that I couldn't make the final move. Once again Ben graciously came the rescue, nailed the pullover and belayed me up. The sun was starting to set, so we used a Johnson sight-level to confirm the summit spire, set up the antenna on the summit spire, and enjoyed the excellent San Juan Sunset.

In order to minimize dGNSS uncertainty, we opted to measure for 2 hours between 8:20 and 10:20 pm. Ben sagely pointed out that it would be just as dark if we ran for 1.5 hours vs 2! I really enjoyed talking to Ben as we watched the sun set and looked South at the lights of the Durango Airport twinkle in the distance. After 2 hours had elapsed, we saved the data and began our repels in the dark. Since only I had brought a headlamp, I went first so I could re-sling anchors if necessary and Ben followed using his cell phone flashlight. Thankfully, the anchors were all in pretty good shape so we made steady progress down. On the first rappel, the rope above Ben knocked down a bowling ball sized rock that he deftly avoided (without dropping his phone). Once off the climb, we hiked back down to camp and went to sleep around 12:30am. What an epic!

The next morning, we woke up around 7 and hiked up to the saddle to perform a saddle measurement. Thankfully, the saddle was narrow, unambiguous, and solid rock.

Due to a less open view of the sky, we recorded 3 hours of data. About an hour in, Ben went off to explore a route up Mount Eolus's west slopes/ledges. I stayed behind to babysit the antenna and Ben was my entertainment as I watched him make quick work of the route.

After 3 hours and Ben's return, we took down the tent, packed up camp and hiked out. Doing the mental math, I figured it would be faster for me to take all the gear so that we wouldn't have to exchange anything in Durango. At the Needleton cutoff, I took all the heavy items from Ben and battled up the Purgatory trial for the next 4 hours. I arrived at the car at 5:45, pleased to have remained relatively fast with such a heavy pack. Ben was incredibly patient and interesting to talk to! I was so glad to share this trip with him!

dGNSS Results

Once back in service, I sent the measured data to Eric for processing. Eric processed the data with three different post-processing methods (all elevations NAVD88):

• Trimble RTX-PP found the summit to be 13733.510 feet with a sigma of 0.069 feet and the saddle to be 13433.579 feet with a sigma of 0.059 feet. This results in a prominence of 299.931 feet with a sigma of 0.091 feet. Using these values we find that there is a 77.6% chance that West Eolus has less than 300 feet of prominence and is unranked.
• OPUS found the summit to be 13733.415 feet with a sigma of 0.072 feet and the saddle to be 13433.589 feet with a sigma of 0.079 feet. This results in a prominence of 299.826 feet with a sigma of 0.107 feet. Using these values we find that there is a 94.8% chance that West Eolus has less than 300 feet of prominence and is unranked.
• CSRS-PPP found the summit to be 13733.560 feet with a sigma of 0.066 feet and the saddle to be 13433.673 feet with a sigma of 0.079 feet. This results in a prominence of 299.887 feet with a sigma of 0.103 feet. Using these values we find that there is a 86.4% chance that West Eolus has less than 300 feet of prominence and is unranked.

None of these methods yield the 95% confidence (or greater) that would be required to officially declare West Eolus a unranked 13er. Further, in order to be conservative, the most uncertain results of the 3 should be used. Therefore, West Eolus remains soft ranked!

This is honestly rather astounding! dGNSS reduced the measurement uncertainty by an average of factor of 8.5, but (using the worst case uncertainty) only reduced the chances of West Eolus being ranked by a factor of 1.2 (2.8 average). Using the LiDAR distribution, I've estimated that the chances of this exact, undetermined situation as being roughly 10%!

Comparing to LiDAR, we find that LiDAR missed about 10.5" on the summit but also missed 5" on the saddle. Further, LiDAR clearly missed the true summit location, being ~4 feet SW of the true location. The LiDAR saddle was much closer, being only 0.8 feet away from the ground truth. I used the Trimble RTX-PP data to find these values and create the following visualizations.

Also, it is important to note that the measurement uncertainties could be improved in a future dGNSS survey with ~4-6 hour summit and saddle measurement times. While not guaranteed, a longer survey could provide in a clear ranked-unranked determination (third times the charm?).

Personally, I find these results to be very fitting for a peak like West Eolus. Is it ranked? Probably not, but a 1/5 chance of being ranked is nothing to sneeze at! While I don't think climbing West Eolus is strictly required to finish the Bicentennials, Tricentennials, or 13ers, it is highly encouraged extra credit! It's a San Juan Classic and, who knows, it might be ranked...