Chapter 1 – Mountains, Valleys, Canyons, Plateaus

Chapter 1: Mountains, Valleys, Canyons, Plateaus

Created by Sarah Choi (prompt writer using ChatGPT)

Mountains, Valleys, Canyons, Plateaus — Formation Logic for Environment Concept Artists

Why geology makes your worlds feel real

Terrain isn’t random noise. It is the visible record of forces that built and carved a planet over immense timescales. When you understand those forces, your sketches, block‑outs, and production assets begin to “click” with viewers. Peaks line up along concealed fold axes, valleys aim themselves toward base level, canyons respect the rock layers they slice, and plateaus crumble logically from their edges inward. This article teaches a practical grammar of landforms—how they are made, what they look like at different ages and climates, and how to translate formation logic into believable silhouettes, textures, and traversal spaces for both concept and production workflows.

The four drivers: Tectonics, Rock, Climate, Time

Every landscape is the negotiation between what lifts land up and what wears it down. Tectonics raises and fractures crust; rock type controls strength and texture; climate selects the tools of erosion—water, ice, wind, salt—and sets snowlines and vegetation; time lets small processes accumulate into big forms. If you can identify the dominant driver in your scene and the runner‑up, you can predict most shapes before you ever touch a brush or sculpting tool. Ask: what is pushing up, what is cutting down, what is the rock made of, and how long has this been happening?

Mountains: building ridges, reading ages

Mountains arise in a few primary ways, each leaving signature geometry. Fold‑and‑thrust belts produced by continent‑continent collisions stack slabs of crust like a squeezed rug; their ridgelines run parallel for long distances and their valleys form trellis drainage that follows weak layers between folds. Fault‑block provinces form where the crust is stretched; tilted blocks rise as steep escarpments (the high side of a normal fault) with broad, gentler back‑slopes that shed fans of debris into parallel basins. Volcanic ranges, whether composite cones or shields, create radial symmetry; lavas and ash blanket preexisting relief and build top‑down rather than bottom‑up. Accreted terranes and ancient metamorphic uplifts expose extremely resistant cores with jagged, joint‑controlled spires.

Age shows in slope language. Young ranges are raw and angular, with narrow V‑valleys and high local relief. Mature ranges are deeply incised; ridges are still sharp but slopes host thicker soils and more trees, and cirques gnaw into headwalls where glaciers linger. Old ranges have low relief and rounded tops; resistant rock may stand as tors and inselbergs above a smoother skyline. Climate modifies all of this: periglacial frost‑shattering leaves talus aprons and avalanche chutes; humid climates mantle slopes in soil and vegetation, softening profiles; arid ranges remain crisp, with bare rock, varnish, and coalescing alluvial fans at the range front.

For concept artists, decide first whether the range is compressional, extensional, or volcanic, then enforce consistent long‑wavelength structure in your thumbnails. Fold belts should repeat layer thickness and dip along strike. Fault‑block ranges should show planar faces and triangular facets stepping along the scarp. Volcanic massifs need coherent radial gullies and stacked flow benches. In production, align stratal textures to world‑space dip and strike rather than UV islands, distribute talus by angle of repose at the foot of cliffs, and let snow accumulate in concavities and lee slopes instead of uniform blankets.

Valleys: water and ice carve in different accents

Valleys are the language of erosion in action. Fluvial valleys begin as small rills that join into V‑shaped troughs. As rivers gain discharge and time, they widen floodplains and swing in meanders. Outside banks undercut into steep bluffs while inside banks build point bars of sand and gravel; when rivers are forced to incise by uplift or base‑level drop, meanders can freeze into entrenched curves perched above the modern channel, leaving terraces to mark former valley floors. Where rock structure guides flow, valleys align along weaker layers, producing rectilinear or trellis patterns instead of dendritic “tree‑like” networks.

Glacial valleys tell a different story: broad, U‑shaped troughs with over‑steepened headwalls, hanging tributary valleys that end in waterfalls, and cirques that bite amphitheaters into ridgelines. Bedrock often shows linear polish and grooves, and deposition leaves moraines and drumlin fields downstream of the ice. After deglaciation, youthful rivers inherit the oversized troughs; their small threads meander across flat valley floors far wider than they could have carved themselves.

To keep river logic believable in both art and level design, remember that water cannot climb hills and prefers the path of least energy loss. Tributaries join the main stem at acute angles pointing downstream, not T‑junctions. Meander wavelength scales with channel width; tight hairpins require either soft banks or recent uplift. Waterfalls need a reason: a resistant layer capping softer rock, a fault step, a hanging glacial valley, or a recent lava flow. In production, spline rivers should respect a real downhill grade from source to base level, and bank materials should transition from bedrock in confined reaches to gravel and fine alluvium across floodplains.

Canyons: incision through layered stories

Canyons develop where uplift outpaces erosion’s ability to widen valleys, or where rock strength contrasts strongly between layers. The classic cliff‑bench profile arises when tough caprock stands vertical while weaker layers beneath erode back into stair‑stepped ledges. Meanders entrenched into rising plateaus carve grand looping gorges with consistent curvature. In arid sandstone, joint networks and rare, violent floods produce slot canyons—narrow, twisting corridors with smooth, overhung walls and chockstones from boulder jams. Basalt flows fracture into columnar joints, creating organ‑pipe walls and talus made of hexagonal prisms; welded tuffs weather into hoodoos capped by tougher rocks.

Visual authenticity lives in respecting stratigraphy. If your canyon cuts sedimentary rock, layers must run through the scene with consistent thickness and gentle warps; any collapse blocks and alcoves should mirror those layers. Color bands should correspond to layer chemistry—iron‑rich sandstones redden and darken where varnish forms, limestones lean gray‑cream, shales break into thin platy debris. Debris size and shape vary down the talus apron: big angular blocks just below fresh collapses, finer scree farther from the wall. For production, a small set of modular cliff pieces can feel vast if each piece encodes a distinct layer thickness, fracture spacing, and weathering style, then is assembled in long, consistent runs that read like a real stratigraphic column.

Plateaus: high tables that unravel at the edges

Plateaus are broad high surfaces lifted by tectonics or built by volcanic floods, then dissected by rivers into mesas, buttes, and badlands. Uplifted sedimentary plateaus keep horizontal layers; erosion starts at edges where rivers gnaw headward into the tableland, creating amphitheater‑headed canyons and isolated flat‑topped remnants protected by resistant caprock. Flood‑basalt plateaus blanket thousands of square kilometers in stacked flows; cooling joints create vertical prisms and step‑like flow fronts. Ash‑rich tuffs weld into soft, easily carved forms that produce bulbous towers capped by harder boulders.

In concept, begin with the intact surface—an almost eerie flatness—then subtract logically along drainages and joints. Edges show the clearest story: sheer caprock cliffs, slopes of crumbly shale or ash, then aprons of fans and pediments that merge into plains. In production, plateaus are performance‑friendly macro forms, but they demand disciplined layering so silhouettes are not random. Blend materials by slope and curvature: vertical faces keep bedrock, intermediate slopes take coarse debris, low concavities collect sands, silts, and sparse vegetation. Place roads and paths along benches and cuesta tops rather than trying to ladder up sheer caprock.

Rock controls: what different lithologies want to do

Rock type is destiny for form and surface detail. Strong, massive igneous rocks like granite resist along planes of joints, forming slabs, domes, and blocky tors; exfoliation sheets peel where pressure is released, giving smooth, onion‑skin curves. Basalt makes columns and tiered falls; it is dark, dense, and “clean‑edged.” Metamorphic gneiss and schist carry foliation bands that dictate serrated, blade‑like ridges and planes of weakness for landslides. Sedimentary sandstone holds crisp ledges and cross‑beds that can be read on eroded faces; shale disintegrates into scree and softens slopes; limestone dissolves into karst—sinkholes, caves, disappearing streams, and tower karst where tropical rains dominate.

When you choose a lithology for your scene, you are choosing silhouette rhythm, fracture spacing, debris texture, and color palette. Encode that choice early so every cliff, boulder, and ground scatter agrees. In production, anchor your shader sets in material families rather than one‑off swatches—granitoids, basalts, sandstones, shales, limestones, schists—and key them to world‑space masks driven by slope, aspect, curvature, altitude, and wetness.

Climate controls: orography, snowlines, and varnish

Mountains rearrange weather. Moist air rising on windward slopes cools and drops rain or snow; descending air on the leeward side warms and dries, creating rain shadows where deserts can sit beside glaciers. Snowlines rise toward the equator and lower toward the poles, but aspect matters locally: north‑facing slopes in mid‑latitudes keep snow longer and grow darker conifers; south‑facing slopes dry and brighten with grass and shrubs. In hot deserts, flash floods gouge narrow arroyos, varnish darkens sun‑baked faces, and biological soil crusts paint fragile mosaics on flats. In cold climates, freeze‑thaw cycles pry blocks loose, solifluction lobes slump on permafrost, and rock glaciers ooze down cirque floors.

For believable scenes, let climate pick the sculpting tools. Give arid cliffs crisp edges, sparse but tenacious plants on ledges, and coalescing fans at range fronts. Give humid mountains soil‑mantled shoulders, tree line transitions with elevation, and thick colluvium in hollows. Show snow drifts in lee pockets and wind‑scoured ridges. Convey ice legacy with U‑troughs and perched erratics even if your world is presently temperate.

Drainage patterns: the fingerprints of structure

Rivers sketch a map of what lies beneath. Dendritic networks form on uniform substrates, their branching angles reminiscent of leaf veins. Trellis patterns align long, parallel streams along folded strata, with short feeders cutting across at right angles. Rectangular patterns reflect jointed and faulted bedrock, with stair‑step bends. Radial drainage flows outward from a dome or volcano; annular drainage circles around domes or basins where resistant rings constrain flow. Pick a pattern that matches your tectonic story, then ensure every tributary obeys it—this single choice yields instant coherence from map scale to shot scale.

Knickpoints, terraces, and base level: placing waterfalls and benches with intent

All running water ultimately aims for a base level—sea, lake, or a tougher rock layer. Where stream power jumps (due to uplift, fault steps, harder strata, or a lava dam), channels form knickpoints—abrupt drops that migrate upstream as waterfalls. Terraces step along valley walls where rivers cut down into their own floodplains during pulses of uplift, climate shifts, or base‑level fall. Use knickpoints to justify dramatic falls and use terraces as natural platforms for paths, fields, or ruins overlooking younger channels below.

Landscape age and story pacing

Landscapes age as characters do. Youthful terrain is extreme in contrast—knife ridges and tight ravines—but often lacks comfortable places to stand. Middle‑aged landscapes host the richest variety of spaces: narrow canyons, broad benches, valleys with usable floodplains, isolated mesas. Old landscapes roll into subdued hills and pediments where only the hardest rocks keep relief. Decide how old your region is relative to its last tectonic pulse or glacial maximum, then let that age inform encounter design, settlement placement, and the density of safe traversal routes.

From thumbnail to level: a practical workflow

Begin with a tectonic sketch: draw arrows that collide, pull apart, or slide past, then place major faults, folds, or volcanic centers. Drop a base level—sea, interior basin, or a through‑flowing trunk river—and sketch a drainage pattern that fits the structure. Choose a lithology palette and a climate. Now rough silhouettes that honor the long‑wavelength structure you established. Only after this do you introduce medium‑scale erosion details like gullies, alcoves, and fan lobes, and then micro‑scale breakdown like block fields, scree, and soil.

In production, convert the same logic into layered systems. Sculpt macro forms with heightfields or signed distance volumes, bake a flow or erosion map to guide channels, then mask materials by slope/aspect/curvature. Scatter boulders where slopes break and along talus toes, not uniformly. Let decals add varnish streaks beneath seeps and rust halos where water runs over iron‑rich layers. Route paths along benches, cols, and ridgebacks rather than straight up fall‑lines. Keep rivers continuous in grade through LODs and avoid disconnected headwaters on ridgelines.

Human logic in rugged terrain

People, roads, and animals select the same sweet spots geology provides. Mountain passes form at cols between cirques and along the lowest saddles on divides. Settlements prefer confluences on floodplains above flood stage, fan apices where groundwater is accessible, and terrace edges with defensible height and fertile soils. Mines chase contacts between layers and fractures where fluids once flowed; quarries exploit resistant ledges right where a valley face already exposes the right stratum. Place ruins where erosion would reveal or undermine them—atop caprock buttes or on terrace margins that later cut back.

Common pitfalls and how to fix them

If a river appears to climb a hill, lower a continuous grade to base level and add a knickpoint where you want drama. If meanders are too tight for the channel size, either widen the floodplain or justify entrenchment with uplift and terraces. If cliff layers don’t match around bends, re‑establish a consistent dip and thickness before adding local deformation. If snow covers sun‑exposed slopes as much as shaded ones, re‑mask by aspect and wind drift. If everything looks like noise, re‑impose the long‑wavelength structure: ridges parallel in folds, stepwise in fault blocks, radial on volcanoes, planar on tablelands.

Regional archetypes to inspire believable variety

A high fold‑belt with ongoing compression yields long, serrated ranges, narrow parallel valleys, and frequent rockfall; treeline sits low on windward slopes due to orographic storms. An extensional basin‑and‑range province alternates steep, triangular‑faceted range fronts with flat playas where ephemeral streams spread fans. A volcanic shield rising from a basalt plateau hosts gentle summit domes, radial lava tubes, and fresh black flows that deflect streams and create sudden waterfalls where rivers breach flow fronts. A limestone plateau in humid tropics dissolves into tower karst—sheer pinnacles and sinkhole basins with disappearing streams—making natural stealth routes and ambush ledges. An alpine plateau recently deglaciated carries U‑troughs, hanging valleys with ribbon falls, and erratics perched improbably on roches moutonnées.

Lighting, color, and scale reads from process

Process predicts light. Canyons bounce warm light into shadowed walls; ledges catch raking highlights that emphasize layer rhythm. Snow cornices glow along lee edges; avalanche paths cut pale scars through darker forests. Desert varnish deepens shadow values; biological soil crust subtly cools open flats. Use atmospheric perspective to stage scale—drier air over plateaus gives long sightlines and abrupt value steps, while humid mountain air compresses distances with blue haze. Reinforce scale by repeating known features at multiple sizes: a caprock thickness echoed in a mesa, a buttress, and a fallen block.

Final checklist before you commit

Ask whether the big form matches its origin story. Do ridges, valleys, and rivers obey structure and base level? Do materials and debris types follow lithology and slope? Does climate explain vegetation, snow, varnish, and soil? Do your dramatic features—arches, waterfalls, towers—have a geological reason to exist right where you placed them? When those answers are yes, your terrain will feel inevitable, not arbitrary, and viewers will sense a world that could keep existing just off‑screen.

Believability in terrain is not about copying one famous canyon or mountain; it’s about honoring the causes behind the effects. When you let tectonics, rock, climate, and time whisper into every silhouette and surface, your environments will carry the quiet conviction of the real world—even when your world is entirely your own.