Loess ravines without the crowds · around Kazimierz Dolny

Loess has a memory. So far we know one date.

The wall of a road ravine records water, wheels and slumps, but a single frame does not say how fast this happens. Alongside: one photograph from 5 June 2010, an empty frame for a second one, and a way of reading the traces without pretending that change is already visible.

The title is not a promise. The archive does not know how many people visit the ravine today.

SCHEMATIC, not a photograph A · schematic of the principle; date of the base photograph 5 June 2010 The drawing is a schematic of the principle, not a photograph or an outline of one. Photograph: source and licence

No second photograph from the same spot. An empty frame does not mean “no change”.

Empty frame: no photograph B · second date none We do not fill the frame with a downpour simulation: a model is not a document.

Zone 1 · overhanging roots

Roots reveal a loss of ground

What you see. A mesh of tree and shrub roots protrudes from the top of the wall and hangs without mineral support.

Process. The roots grew in the soil. As water and wheels lowered the road bed and the banks retreated, the ground around them was lost and the roots were exposed.

Limit of inference. Exposed roots prove a loss of ground, but without repeated measurements or photogrammetry they do not allow you to calculate the rate of erosion or the former level of the road bed.

Question from the road. Below the roots, is there a pale, fresh slump surface, or has the surface had time to become overgrown? Look from the road; do not approach the bank.

Zone 2 · vertical surface

A vertical wall describes a mechanism, not stability

What you see. A high, almost vertical wall with vertical lines of cracks and in places paler surfaces.

Process. Loess with vertical cracks (jointing) can stand almost vertically. When water or wheels undercut the base, blocks lose their support and break away under gravity.

Limit of inference. A vertical bank proves neither the absence of erosion nor stability. From a single photograph you cannot judge whether a crack is active.

Question from the road. Can you see open cracks or fresh, pale patches in the wall, or is the surface uniform? Stay in the middle of the road.

Zone 3 · road bed

The furrow shows where the water ran off

What you see. A longitudinal depression in the road bed, running along the axis of the road or along the wheel tracks.

Process. Wheels destroy the turf and break up loess dust. During rainfall, concentrated water carries off loose material and cuts into the road bed.

Limit of inference. A single furrow does not separate the effect of rain from the effect of wheels: water uses every depression.

Question from the road. Does the furrow run down the middle of the road bed as a single channel, or is it formed by parallel ruts in the wheel tracks?

Zone 4 · slowing of runoff

Sediment shows where the water slowed down

What you see. A flattening of the road bed with pale, fine-grained silty sediment, often at the outlet or below the wall.

Process. As the gradient of the road bed decreases, the water loses energy and no longer carries fine particles; loess dust settles.

Limit of inference. The amount of sediment in one place does not measure the whole of the erosion, and the sediment itself can be moved.

Question from the road. Does the sediment fan out at the outlet, or does it lie locally just below a fresh slump?

What you may write under a photograph

This page has one base photograph, so its own state is the first row below. Choose what you have and see how what you can honestly write about the wall changes. The page does not load, send or save photographs, dates or notes.

One observation: the starting point of the documentation

Applies when: you only have the photograph from 5 June 2010.

You may write: describe what is visible in the photograph from 5 June 2010, and name the process that such a trace usually indicates.

You may not infer: that the wall is retreating, that the furrow is deepening, or that the place is stable. The absence of a second photograph does not mean “no change”, nor does it mean “zero change”: it is missing data.

A pair in time: two photographs from the same spot and framing

Applies when: you have a second photograph with a valid date.

You may write: point out the difference visible between frames A and B, giving both dates and the interval between them.

You may not infer: the rate of erosion, its cause (rain, wheels, frost, works) or the sequence of events. A pair describes the state on two days, not what happened between them; the interval may have included many downpours and droughts.

Different frames: you are comparing views, not the same terrain

Applies when: the second photograph has a different standing point, angle or extent.

You may write: describe how the frames differ: standing point, angle, width of the shot.

You may not infer: that the differences are a change in the terrain. The same furrow photographed from a different angle looks different.

For each zone, also note a fixed reference point in the frame; the zone descriptions above suggest what to look for.

Where such a wall comes from, and what is missing here

Loess is a porous rock made of fine grains blown by the wind, easily susceptible to water erosion [2]. Wind deposits, water cuts: a furrow shows the direction of runoff, an exposure shows the material, and sediment shows the place where the water slowed down.

The drawing at the top of the page is an author's schematic of the principle. It is not a map, an outline of a photograph or a measurement of the wall's geometry, and it does not indicate a place that can be entered.

Three sites, three questions

Korzeniowy Dół: An example of a road ravine, developed by wash along the road and by the action of wheels [1]. Question: how do ruts and the slope of the road concentrate a stream of water?
Norowy Dół: A ravine linked in the study with the slope of the terrain, the substrate and soil erosion [1]. Question: how does the profile of the bed change as the gradient increases?
Doły Podmularskie: A site described in the literature as a geological exposure [1]. Question: do you see uniform loess dust, or a contact with the bedrock? The register entry [3] is named “Podszyńskie Doły”; whether this is the same site needs checking.

The site descriptions come from an earlier version of the page; the content of the publications was not re-read here.

What was removed relative to V2

The hypothetical “post-downpour model” with an outline of the slump. It could pass for a second state of the wall. Replaced by an empty frame B and a caption gate.
The ⇄ button and three switchable layers. They compared the photograph with the model. Without the model they have no purpose; the two frames now stand side by side.
The notebook with presets A, B, C, saving in the browser and copying. The “difficulties / warning” result suggested an assessment of conditions without data. Moved to the list of signals and questions below, without saving anything.
The embedded photograph from an external server. The page is meant to work offline, so the photograph is a link in the sources.
Numbers without a basis (the height of the roots, a “several-fold” acceleration of incision).

In the field: signals and questions, not a result

This list does not assess whether the route can be walked. The absence of signals is not permission to enter, and the state of the wall and the road bed changes after every rainfall.

Turn back or ask the manager if you see

flowing water in the bed of the ravine,
fresh, pale slumps or hanging lumps without support,
thick, sticky mud in which it is hard to keep a firm footing,
a current weather warning about storms or heavy rainfall.

Rules for observing

Stay on the road. Observe from the open trail; do not approach banks and overhangs, do not climb, do not break off lumps.
Do not touch the roots. Hanging roots are part of the top of the wall; tugging them may speed up the detachment of the overhang.
Keep away from the edges from above. On the plateau just above the edge, the turf may give way under your feet.
Do not dig in the loess. Disturbing the surface may initiate new furrows.

To check before setting out

This archive does not settle these, and neither does this page:

whether the road is accessible today and who manages it,
whether photography is allowed in this place and whether any restrictions apply,
what the current weather reports are and what has happened in recent days,
how many people go there: “without the crowds” is a slogan in the title, not an established fact.

A photograph from 2010 does not prove that it is dry, safe or empty today.