How to read a valley from elevation, contours and satellite imagery before you go.
How steep it is and where the gradient changes. Contours packed close together along a stream mean a steep, fast stretch; contours spreading apart mean the stream flattens. The point where they change from packed to spread is a slope break.
Follow the stream downhill and watch the spacing of contour crossings. Where several crossings come in quick succession and then the gap suddenly widens, the gradient has dropped. Mark that point; the traps are just below it.
The shape of the ground: ridges, side valleys, benches and terraces stand out as light and shadow. Hillshade makes old channels and flat terraces on the valley side visible, which contour lines alone can hide.
A digital elevation model — a grid where every cell holds the ground height. Everything about gradient, catchment and stream shape is computed from it. Its resolution decides how small a feature it can see.
It sees the valley: gradient, bends wider than a few cells, junctions and constrictions. It does not see a single boulder, a bedrock crack or a bar narrower than its cell. Use it to choose the stretch; use your eyes to choose the spot.
Trace the ridges around the stream above your point — the divides where water would flow one way or the other. Everything inside is the catchment. Then ask what rock is inside it; that is where any gold would come from.
Which way it faces. Aspect affects snowmelt timing, vegetation and access more than gold itself, but it helps plan a day: shaded slopes hold ice and moss, sunny slopes dry first.
Look for a curving line of different vegetation or a pale gravel strip across a meadow, parallel to or crossing the present stream. Old channels grow different plants because the gravel drains differently.
Pale, crescent-shaped strips of gravel on the inside of bends, pointing downstream. On satellite imagery at low water they are obvious; at high water they vanish, so check imagery dates.
Sometimes: darker, blocky texture in the channel, often where the valley narrows or the stream bends sharply. Rapids and short steep steps in the stream are the usual sign of bedrock underneath.
Contours from both sides pinch toward the stream, and the flood plain disappears. Below the pinch the contours open out again. That opening is where the water slows.
Follow tributaries upstream on the map and see what they drain. A tributary that comes from steeper, more mineralised ground is worth more than a bigger one from gentle farmland. Check the bar on that tributary’s side of the junction.
A way of ranking streams by how many tributaries feed them: a headwater with none is first order, two of those joining make a second, and so on. Low to middle orders — walkable creeks — are usually the most practical for hand prospecting.
A profile plots height against distance and shows every slope break as a bend in the line. Reading a profile is faster than reading contours: a steep segment followed by a flat one is a trap zone.
Listen and look. Fast, noisy water over rapids means a steep stretch; quiet pools and long riffles mean it has flattened. Walk upstream until the character changes — that change is the break.
A flat step on the valley side, above the present stream, made of old stream gravel. On hillshade it shows as a level shelf; on the ground it is a flat bench with rounded stones. Terraces are the stream’s former beds.
No. Mapped stream lines are approximations, and channels move. Use the map to pick the stretch and the features; confirm the actual channel and bar positions on the ground or with recent imagery.
It tells you what rock is in the catchment. Quartz veins, altered zones and old volcanic rock are the usual gold sources; a stream draining only young sediment is unlikely to carry gold no matter how good its traps look.
Every marked occurrence — a vein, a prospect, an old working — is a possible source. Streams that drain from those points are the ones worth walking. Occurrences inside a catchment are worth more than ones beside it.
Start at the first good traps below the source and work down. Gold thins and fines with distance, so the first slope break, bend or junction below mineralised ground is usually the best stretch.
Access decides what you can actually work. A rich stretch three hours from any track is a different plan from one beside the road. Check tracks, crossings and where you can leave a vehicle before choosing between two similar stretches.
Walk upstream. You see the traps from below, which is how the water sees them, and you finish at the top where the gold is coarser. Mark the spots to sample on the way up and work them on the way down.
Measure the length of the stretch you plan to walk and the drop across it; length over drop gives gradient. Measure distance from the road to judge time. GOLDONGO’s measure tool does both on the map.
Usually, and you should check. Parks, reserves and heritage sites are mapped, and GOLDONGO marks them and drops the streams inside them from its lists. Whatever map you use, learn which areas near your stream are closed.
Three questions: is there a source in the catchment, does the profile show slope breaks and bends, and can you get there. A valley that fails the first question is out regardless of the other two.
GOLDONGO scores entire stream networks for the trap geometry this guide describes — slope breaks, inside bends, junctions and bedrock. Pick your region and see where it stands.
This guide is general education, not advice for a specific place. A score, a map or a sentence here is not a licence to dig: the rules for prospecting, land access and protected areas differ from place to place — learn the ones that apply where you are before you go.