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A gold-prospecting research map for California's six northern counties (Shasta, Trinity, Siskiyou, Humboldt, Tehama, Butte — the Klamath, Salmon, Trinity and Feather River gold country), built entirely from official public data: the full USGS Mineral Resources Data System, CAL FIRE burn perimeters, USGS 3DEP LiDAR elevation, FEMA flood zones, USGS fault and stream-gauge data, and the live BLM mining-claim index. Data pulled June 15, 2026.
The model walks every mapped stream, keeps points in proven placer ground, and scores each 0–100 by cross-referencing the established gold-geology criteria (USGS placer deposit models) against real datasets: 19% placer-working density within 2.5 km; 8% recorded production size; 7% producing lode mines within 3 km; 8% gold-favorable host rock (greenstone belts, ultramafics, metasediments); 6% structural control — mapped faults within 800 m; 7% catchment size — the total upstream drainage area (NHDPlus), because more gold-bearing country above a point delivers more gold to it; 8% post-2014 burn-scar recharge; 5% floodplain width; 6% slope-break (canyon-exit dump zones); 7% low local gradient (deposition zones); 5% bend sharpness; 5% stream confluences; 4% the 200–1,100 m foothill band; 5% ancient Tertiary-channel indicators. Each target is enriched with watershed, drainage area, land owner, live claim status, nearest live stream gauge, host rock (serpentinite flagged), fault count, and two LiDAR-read measurements. That's the full source-to-placer chain — favorable rock + faults (source) × a big catchment to gather it × low-gradient traps (collection). A high score still means pan-test it first; no model sees through gravel.
Using the USGS 3DEP elevation data, the model runs a cross-valley transect at each target and reads two things off the terrain: floodplain width — how far the flat, near-creek-elevation valley bottom extends, i.e. the ancient/active flood-deposit belt where flood gold spreads and drops (a broad floodplain ≥120 m is called out in the popup); and the bench / terrace scan — the first flat shoulder 8 m+ above the creek, which is a stranded paleo-channel holding old, often-untouched gravels. Turn on the two LiDAR layers (hillshade + slope) to see these benches and abandoned channels with your own eyes, then use the popup numbers to know how far up and which way to climb.
Placer gold doesn't form in the creek — it erodes into it. The original gold crystallized in quartz veins (lode/hardrock) when hot mineral fluids rose along faults and shear zones through favorable rock (greenstone, serpentinite, metasediments). Over millions of years those veins weather and shed gold downhill; water sorts it by weight and concentrates it in the stream — that's your placer. So the chain is: favorable rock + fault → quartz vein outcrop (lode) → erosion → placer in the drainage below.
The app now shows both ends of that chain as separate, toggleable types under “Documented gold sites”: red = lode/hardrock mines (the SOURCE) and amber = placer workings (where it collected). To find fresh ground: pick a red lode site, look uphill for its quartz vein outcrop (often iron-stained/rusty “gossan” rock, white quartz float on the surface), and work the first drainage below it — especially where that drainage hits a flat, bend, or bedrock. The honey-hole model already rewards reaches that have lode sources within 3 km and sit on favorable host rock, which is exactly this source-to-placer logic scored automatically. To read the outcrop itself, turn on bedrock geology (favorable belts) plus the LiDAR hillshade (to spot the ridouts, cuts and benches) and zoom in with Satellite for surface color/quartz.
Gold rarely travels alone. The ⚙ Mineral commodities layer plots 3,461 non-gold mineral occurrences from the USGS database, and the most useful ones for a gold hunter are chromite (green — chromium ore that marks serpentinite/ultramafic belts, exactly the Klamath gold host) and mercury/cinnabar (red — the classic companion of California lode and placer gold). Silver and copper often run in the same quartz-sulfide veins as gold. So a cluster of chromite + mercury + a fault is a strong “gold belt” signature even where no gold is recorded yet. Toggle each commodity on/off; tap any dot for what it is and why it matters.
The surface only shows part of the story; geophysics sees under the cover. The 🧭 aeromagnetic overlay (NOAA EMAG2) maps magnetic anomalies — serpentinite bodies and mafic intrusions read as magnetic highs, while some altered/mineralized zones read as lows; the boundaries (gradients) often follow the deep faults that channeled gold fluids. The 🌏 isostatic gravity overlay (USGS) maps buried density — gravity highs = dense mafic/ultramafic rock, lows = granitic intrusions or basins; the steep edges mark concealed structural boundaries and contacts. Where a magnetic or gravity gradient lines up with mapped faults, lode mines, and chromite/mercury, you're reading a buried source zone — the kind of ground that fed the placers downstream. These are regional-scale, interpretive layers (coarse resolution) — use them to spot belts and trends, then confirm with the geology, structure, and a pan.
Host rock matters more than most prospectors realize. The region's gold rode up in quartz veins through specific rock belts — greenstone/metavolcanics, serpentinite/ultramafics, and metasediments (slate, argillite, chert). The bedrock geology overlay (USGS State Geologic Map) shades those units, and every honey hole's popup names its host rock and flags whether it sits in a gold-favorable belt — an 8% factor in the score. The earthquake layer (USGS, M3+ since 1980) traces today's active faults and shear zones; those same structures are what fractured the rock and channelled the gold-bearing fluids. Where dense seismicity and mapped faults sit near lode mines, you're looking at vein-source country feeding the placers downstream. (Seismicity is context, not a direct score input — the gold signal is the host rock and fault proximity, which the model already weighs.)
The Data table button (top bar) opens every site — honey holes, scout mines, and placer workings — in one sortable, filterable grid. Click any column header to sort; filter by minimum score, maximum distance from your address, unclaimed-only, gold-favorable-rock-only, burn-recharged-only, or a name/stream search. Tap a row to fly there on the map, or hit CSV to export exactly what you've filtered for a spreadsheet or to share.
Amber stars: the only 32 gold sites in the region with recorded Large/Medium production. Hammers: 186 workings whose first dated activity precedes 1941 — green if USGS still carries them as “Producer”, gray if abandoned. Dark-red hammers are the war-stopped class: last recorded activity 1930–1942, never restarted — in October 1942 the War Production Board's Order L-208 shut every US gold mine, and many owners (some of whom died overseas) never came back; pay gravel was often left in place. Every site shows live claim status. Famous lode mines are often patented private land the federal claim index can't see — verify parcel ownership. Never enter old adits or shafts.
Placer gold drops where water slows: inside bends, gravel-bar tails, behind boulders, bedrock cracks, canyon exits, and confluences — always dig to bedrock or false-bedrock clay. Use the topographic basemap and the two LiDAR layers (1-m bare earth): hydraulic pit scars, dredge-tailing corduroy, stranded terrace benches and abandoned meanders all jump out of the hillshade; benches show as flat green ribbons on the slope map. Burn scars recharge the creeks below them for several winters; flood zones mark flood-gold ground; faults mark vein country that feeds placers downhill. Check each honey hole's live gauge link before driving out — work reaches as flows drop after the spring melt.
Straight talk: the app can't scan imagery and auto-detect anything — there is no computer vision here, and nothing “finds” hidden sites for you. What it gives you is the same set of layers used to spot old workings by eye — you do the finding:
1) LiDAR bare-earth hillshade = see through the trees. Bare-earth LiDAR strips the vegetation away, so under forest canopy you see the ground itself. Turn it on (2.5× exaggerated) and zoom in: look for shapes nature doesn't make — scalloped hydraulic-mine pit walls, ditches & flumes contouring the slope, corduroy dredge-tailing rows, terraced platforms, raised road grades, and rectangular cabin/headframe foundations. These jump right out — exactly how people relocate lost diggings.
2) Historical topo maps = what used to be there. The 📜 Historical topo overlay shows USGS quads back ~100+ years. A mine, mill, ditch, or cabin drawn on a 1900s map that is gone from today's satellite is a prime spot — flip between historical topo and Satellite at the same place to find them.
The method: scan the LiDAR hillshade for unnatural shapes → check the same spot on historical topo (was a mine there?) → confirm on Satellite → drop a waypoint and go look. The 👁 Inspect targets layer pre-marks documented dredges, hydraulic pits and drift mines to start you off.
What this can't do: there is no public ground-penetrating-radar or magnetometer data — nothing free sees gold under deep gravel. Depth-to-bedrock soil datasets exist but are coarse, come as raw data (not viewable), and skip active river channels entirely — useless for the creek bed where you'd dig. And for most inland rivers, including the Sacramento at China Rapids, no underwater (topobathymetric) LiDAR has been flown, so elevation shows the water surface, not the channel bottom. I checked all of it — that x-ray view isn't in the public data; it takes a pan and a test hole.
But you don't need to see THROUGH the gravel where there isn't much gravel. The whole game is finding where bedrock is shallow or exposed — that's where the pay layer is within reach. The new ⛏ Exposed bedrock layer plots every mapped rapids, falls, and rock outcrop: rapids exist because bedrock crosses the channel, so at each one the gold sits in the bedrock cracks, crevices and potholes right under shallow water — the closest thing to “digging to bedrock” without digging. China Rapids itself is exactly this: a bedrock rib across the Sacramento. Work the cracks and the slack water just below each rib.
What actually penetrates, and is now built in:
1) Read the bottom optically. In clear, low water (late summer–fall, after flows drop), the river bottom is visible from above — gravel bars, exposed bedrock, and deep pools (which read darker). Switch the basemap to Satellite and zoom all the way in (now to z22). At China Rapids you can trace the bedrock ribs and the slack water behind them where gold settles. Best results on imagery captured at low flow.
2) Read the dry ground in fine detail. The LiDAR hillshade is now a 2.5×-exaggerated multidirectional render — the crispest setting — so terraces, paleochannels, hydraulic pits and dredge tailings stand out sharply. The new 2-ft contour lines layer adds exact micro-relief: tight, bunched contours = a bench edge or bedrock rib; wide-spaced = a flat where gold settles. Stack the elevation tint under the hillshade for colored relief.
3) Read the water level. Each honey hole's live USGS gauge tells you the depth/flow right now — the lower it is, the more bottom you can see and reach. China Rapids sits below the Bend Bridge gauge on the Sacramento.
Green-hatched areas hold someone's active claim — prospecting there without permission is claim-jumping. To stake open federal ground: confirm it's unclaimed BLM/USFS land and not withdrawn (national park, Wild & Scenic corridor); stake corners and post a location notice; record with the county AND file with BLM within 90 days (mlrs.blm.gov; roughly $260 to start, ~$200/yr or the small-miner waiver; 20 acres per person for placer).
Two layers answer “whose land is this?” without you setting foot on it. ✅ Public vs private land shades every parcel a public agency manages — BLM, National Forest (USFS), state, etc., color-coded, with the agency named when you tap it. Anything NOT shaded is private — treat it as no-go without permission. This is the real anti-trespassing tool: casual panning is generally fine on the shaded public land (where it's not claimed or withdrawn), and never okay on the blank/private ground. 🛣 Property lines draws the actual county parcel boundaries when you zoom in, so you can see exactly where one ownership ends and the next begins.
About owner names: the counties deliberately keep owner names out of their free public map data for privacy — that database is what paid apps like onX and Landgrid license. So instead of a name on the map, each parcel popup gives you its APN/address and a one-tap “look up owner” link to the county assessor (free), where the name is public record. If you want owner names rendered directly on the map, onX Hunt or a Landgrid subscription is the only way to get that legally.
The 🪨 Cave terrain layer shades the geology where caves form: purple = limestone/marble (dissolves into classic caverns and sinkholes), teal = volcanic rock (forms lava-tube caves — this region has vast lava-tube fields). It also drops pins on famous public caves you can actually visit: Lake Shasta Caverns, Subway Cave, Pluto's Cave, Samwel Cave, and Lava Beds National Monument (700+ tubes). One honest limit: the exact locations of wild caves are withheld by federal law (the Federal Cave Resources Protection Act of 1988), so no public dataset maps cave entrances — this layer shows the terrain where caves occur, plus the developed caves that are already public. For gold, carbonate cave terrain often coincides with the contact zones that host quartz veins.
The 🔽 Trails layer draws the official US Forest Service trail network color-coded by who's allowed: solid red = motorized (4WD, ATV, dirt bike), purple = mountain bike, dashed green = foot & horse. Tap any trail for its name, exact allowed uses, surface, and a reminder to check seasonal closures and the local Motor Vehicle Use Map (MVUM) before riding — it's how you find the legal way in to a remote honey hole.
The 📜 Mining claims layer now has a dropdown: active only (green — currently held, need permission), inactive only (gray — lapsed/closed claims, ground that may be open to re-stake), or both. Cross-reading a high honey-hole score against inactive claims is a strong tell: someone proved the ground worth claiming, then let it go — possibly open now.
Type your address or town in the box at the top of the panel and hit Set. A home marker drops, and the list switches to “closest access to my address” — every honey hole, scout site and placer working sorted by straight-line distance from you, nearest first, each tappable to fly there. Switch the list dropdown back to “honey holes by score” any time; distances also show inline on the scored list while an address is set.
Every pin links to Google Maps and 🌍 Google Earth (text the Earth link to a friend and it flies to the exact spot). The Google Earth file button exports every pin with GPS in organized folders — opens natively in the Earth app, Earth Pro, or earth.google.com. The GPX button loads the targets into a Garmin, onX or Gaia for offline field use. The 📍 button shows your live position; press-and-hold drops a waypoint with copyable GPS.