Boynton Canyon Vortex

campcoyote

Every few months I hear the same claim on trail and in shops: “Boynton Canyon’s vortex scrambles compasses and drains phone batteries.” I’ve been around long enough to know most nav failures are user- or gear-induced, not geology or mysticism. Before we keep repeating this, can we treat Boynton as a controlled field test and settle what’s actually happening to our gear?

What I’m looking for:

Measurable effects on navigation instruments: baseplate/Brunton compasses, phone magnetometers, GPS receivers (lock time, SNR, HDOP/VDOP), baro altimeters, and watches with IMUs.
Battery behavior: normal vs accelerated drain with controlled radio states (airplane mode on/off), screen time, and logging apps. Canyons can force phones to transmit at higher power; that’s a mundane explanation, but let’s quantify it.
Repeatable mitigation: if there is a modest magnetic anomaly, what loadout/settings keep us honest? If not, which common gear confounders are actually to blame?

Proposed community test protocol (simple, repeatable, no lab coat required):
1) Sites: pick 3 points-Boynton “vortex” lookout, a nearby non-vortex red rock bench, and a distant control of similar rock type/elevation.
2) Instruments:

Analog: 2 different baseplate compasses (different brands/ages) and, if possible, a Brunton or mirrored sighting compass.
Digital: two different phones with a magnetometer logging app (records µT), one dedicated handheld GPS (log SNR, satellite count, HDOP), and one watch with baro altimeter + compass. Optional: an external BT GPS puck.
3) Setup controls:
Calibrate phone compasses away from vehicles/benches.
Place analog compasses on a non-magnetic surface (wood/plastic), chest-high on a carbon or wood trekking pole or plastic tripod.
Keep a 1 m “no metal” radius: remove phones, knives, camera plates, trekking poles with flick-locks, steel-shank boots, MagSafe cases/rings, hydration hose magnets, watch bands with magnets, earbuds case, belt buckles, etc. You’d be shocked what a MagSafe ring does to a needle at 30 cm.
4) Measurements (2-minute blocks at each site):
Analog bearings to two distant landmarks (₆₀-120° apart), repeated by two people, then swap compasses.
Phone magnetometer total field (µT) and heading; record spikes, not just smoothed headings. Note solar azimuth as a cross-check for expected bearing.
GPS: time-to-fix from cold start, satellite count, SNR distribution, HDOP/VDOP. Save GPX/fit with raw metrics if your device allows.
Battery: start/finish percentage with screen-on time and radio state noted (airplane mode vs LTE). Repeat both ways.
5) Replicate at all three sites, then post raw logs/screenshots. If anyone can bring a proper gaussmeter/fluxgate (not a novelty “EMF meter”), even better.

Questions for the hive mind:

Has anyone logged raw magnetometer field strength at Boynton and compared it to a control? Normal Earth field is ₂₅-65 µT; what did you see?
Any Garmin/Suunto/Coros users with satellite SNR/HDOP plots in-canyon vs out? GNSS multipath from cliffs will explain a lot.
Geology folks: any published magnetic anomaly maps for the Schnebly Hill/Redwall units there? Iron oxides in sandstone could bias a needle a few degrees locally, but “spinning compasses” seems unlikely.
Drone pilots: any repeatable IMU/compass calibration failures in that spot versus other canyons with similar walls?
Practical mitigation: beyond “carry a map and analog compass,” are you leveraging watch IMU headings (gyro-only), sun compass techniques, or external GPS pucks to stabilize nav in multipath hell?

If we find nothing unusual beyond canyon RF and the usual “my phone case is a magnet” problem, let’s stop telling newcomers that Boynton fries gear. If we do find a small but real anomaly, great-let’s quantify it and list the settings and backup tools that make navigation boring again.

trekgearjunkie

I’ve hiked Boynton a dozen times and yeah, the vortex talk is mostly New Age fluff-I’ve never seen a compass go haywire there that wasn’t due to my own setup. On magnetometers: I ran a quick test last spring with my Pixel 6 using Phyphox app at the main vortex spot vs. a control near Dry Creek. Got 48-52 µT both places, dead consistent with local geomagnetic field (no spikes over 55 µT even near iron-rich outcrops). Phone headings stayed true after calibration, no drift.

For GPS, my Garmin Fenix 7 logs show typical canyon multipath-SNR dipping to 25-30 dB-Hz on obstructed sats, HDOP around 3-5m in the narrows vs. sub-2m open. Cold starts took 45-60s there, but that’s cliffs, not magic. Battery-wise, airplane mode saved me ₂₀% on a 10-mile loop; full LTE chewed through 40% faster due to signal hunting.

Geology angle: USGS maps for the area show minor magnetite in the Schnebly Hill Formation, but anomalies are <5 nT-way too weak for needle deflection beyond 1-2°. No published “vortex” data, just standard redbed remanence.

Mitigation I swear by: Sun compass via watch app (e.g., Suunto’s solar mode) for backup, and a Bad Elf GPS puck for clean GNSS without phone drama. Let’s crowdsource those logs-I’ll upload my GPX from last trip if it helps baseline.