The Age of Tracks, and Trails

When don’t raindrops dimple mud?

The causes and signs of weathering are discussed here to explore, and encourage others to continue creating and improving illustrations of this essential tracking concept.

Figuring out when a track was left (aging it) is a fundamental tracking concept.

Locating the story in time moves the tracker an important step closer to understanding interactions within the natural community.

Ask the last person lost in the woods who was rescued alive because a team of skilled trackers identified and followed the most recent part of that person’s trail.

The signs of weathering are always present, the other ways to age tracks may not be.  Except for sightings and trail cameras, weathering generally provides the most precise timing information.

Definitions used here:

weathering“: the process of change in a track.  This begins as the track is being created, includes all of the ways the appearance, contents, shape, or existence of the track are affected by external environmental events, and the process may continue for the lifetime of the track.  Weathering always follows the laws of physics, chemistry, etc..

   A few examples: variations in color of the substrate, alterations from the original shape of the track, location of the track itself, and the absence or presence of objects, related or unrelated to the track.

 “aging“: the weathering of a track, or the activity of estimating its age by examining the signs of weathering in and around the track and trail, and using that information to deduce the age of the track.

   It’s all got to make sense and agree.

How long are tracks useful?

Tracks carry useful information for as long as they exist, and can last for millions of years; continually changing, and accumulating signs of weathering as the moments flow by.  There is current scientific interest in fossilized tracks, “Neoichnology”.  Scientists developing this discipline are employing all the relevant tools of modern science to interpret fossilized tracks, gleaning as much information as possible about the animals involved, and their behaviors.  This work includes estimating the age of the tracks.

What is the oldest track someone has found useful?  The following reference is to a paper published on 2002 by someone pulling meaning from tracks that are about a billion years old.

Rasmussen, B., Bengtson, S., Fletcher, I. R. & McNaughton, N. J. Discoidal impressions and trace-like fossils more than 1200 million years old. Science296, 1112 – 1115 (2002). | Article | ISI |

Focus helps …

A little focus often improves skills we already possess.  From life experience most of us already know how to extract information from some signs of weathering.  You’ve noticed the damp spots left on the sidewalk by the first few raindrops?  The puddles after the rain, and the mud exposed as those puddles fade.  And what later raindrops did to that mud?

How did the mud alter with age?  Change colors, dry or crack?  With the right kind of focus, helped along by learning materials shaped to foster it, how hard would it be to figure out how long it takes for that kind of mud to dry to a particular shade of gray (what factors control that process)? Or to reach a certain degree of cracking?  Which came first, the muskrat or the rain?   Are all raindrops the same size?

Muskrat

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What follows is descriptive information about reading the age of tracks, included to offer insights to areas where illustration may help.  It is not meant as instruction in how to… (if you disagree with any of this information, or think there is an error, please discuss it with the author … everyone makes mistakes, owning and correcting them helps us all.)

What is reading the age of a track, and how is it done?

Reading a track’s age is a deductive process in which one assesses the signs of weathering of the track, judging how long those signs took to reach their present state.   Combining those estimates with other factors like the timing of weather events, and even the animal’s usual behaviors, narrows the possible time frame within which that track could have been created.

A simple example might be;

– In the morning you cleared an area of ground and fluffed it up with a rake.

– Hoping to avoid ruining a pair of shoes you focus on the mower as you trim the lawn that afternoon.  The lawn mower scattered grass clippings across the whole bit of ground you’d cleared.

– The next morning when you go out to check, you have a rough time frame for the age of any tracks left there.  The grass clippings scattered across the ground have dried some, their color changing.  A house cat left a trail across the area, and the grass clippings are not pressed down into its tracks.  All the grass clippings in the raccoon tracks have been bent and pressed into the soil.  Compared to the cat tracks, those left by the raccoon appear crisper, the edges more sharply defined, and some of the disturbed soil a shade darker than similar areas in the cat tracks. Who came last?  And if you leave those tracks in place or go back every so often to line up a new one of your own, what else can you see?

The causes of weathering?

Causes may be things like time and sunlight (slow and persistent), on up to faster events like tsunamis, or meteor strikes.  (Everything is always weathering, both the track and the undisturbed soil around it, with differences).

A few other examples; weather, gravity, wind, water, heat and cold, soil movement, falling objects.  Static electricity?  Does soil ever decompress after it’s been stepped on?

“When stress is removed from a consolidated soil (reduced in volume), the soil will rebound, regaining some of the volume it had lost in the consolidation process.” (https://en.m.wikipedia.org/wiki/Consolidation_(soil))

At first some causes of weathering may seem tricky to perceive or illustrate (try!!).  It is a blessing that everything weathers according to the same rules of physics, chemistry, etc.  Even though the signs of weathering may vary, depending upon things like the environment the animal passed through, the season, the size of the animal, even the animal’s “usual” habits, the tracker can rely on everything following the same rules.  How would the broken end of a living twig weather after the moose browsed off the end, or after the lost hiker tore it off as he blundered through?  Maybe a different break, but same rules of weathering, right?  But how does moose saliva affect weathering of that twig?

The Ford

The signs of weathering one looks for?

A few are: changes caused by rain, dulling of crisp imprints, wind-blown debris or objects fallen in, erosion, changes caused by expansion and contraction, change in color, more recent tracks.

Making one’s own list of the causes of weathering, the signs and the ways they change is no waste of time!

Some signs can be influenced by several factors.  How many factors might influence the signs in this situation?

– it’s mid-morning and you’re walking east.  As you reach a stream you notice:
– a barefoot human track left on a shaded rock the sun hasn’t reached, the track still damp but just visible, and headed west …
– after you cross the stream, you find a trail of larger barefoot human tracks.  The closest is really wet, headed east, and on a rock that’s been in the sun for a while?  (Could stream flow have carried anything away?)

How does one interpret the signs?

See, this is a really interesting part!  Noticing the signs is a necessary first step.  Learning how they change, or what they mean is the next waypoint.  Questions usually help (they’re also a good source of material for illustrations).  “Why is that different?” is frequently fruitful.

Groups of sign

It often helps to combine the info from more than one sign of weathering.  An example, it’s six a.m. on a summer morning.  That deer track looks pretty fresh, the shading looks new, but there’s a sharp and crisply defined robin trail right across it.  The robins usually get up about first light, already foraging while things are still dim and gray.

Causes

Once you’ve noticed the signs you can figure out the causes, and can begin to decide out how fast the changes probably happened.

Variations

The variations specific to things that cause weathering are helpful.  Take wind as an example; in what ways might its changes affect the weathering of a track?  What kinds of differences does wind exhibit in the area where you are tracking?  If you consider the possible ways each contributor to weathering can change, the list grows, but may be more helpful.  Did the wind blow from the south all day, were there strong downdrafts just before that thunderstorm almost happened?

It is still good news that the processes of weathering obey the same laws.  It means there is predictability, for all tracks, in how, why, and the rate at which they weather.  And the news gets better … with a little organization, that list of causes and signs can be a real help.

Prediction

Once the more obvious signs of track aging are understood, it is also possible to predict how a track might appear after some certain length of time.  If a track is examined to see how it compares to that prediction, it will sometimes reveal another layer of the story.  “That track looks different from what I expected, now why…?”.

For example; you know you’re going out to check that track patch you made in the back yard.  If there was a track in it,  maybe there could be some high points and some lowest spots in the track (and not just the claw holes).  Maybe those different vertical levels wouldn’t weather exactly the same?  So if that were true there ought to be some observable difference between them?  So you get out there and yeah, you can see a difference like that in some of the tracks, but not in all.  Why are they different?

Location – Think a track’s location can’t change?  How much did that lake bed shift up down or sideways after it filled in (which preserved the tracks of the last dinosaur herds), turned to stone and became part of a mountain over the course a few million years?

Precision of age estimates (how close you can resolve the timing) … Expectations and reality

Precision varies, even within a trail, from “Exactly at” to “Probably was”.  And there can be a lot of “Between some time and now”.  Though not always, there is usually some degree of uncertainty in an age estimate.

When exact age is not possible, it must be estimated.  Estimates can depend on one’s knowledge, experience, and state of mind (tired minds don’t work as well), plus all kinds of other factors.  An example would be physiology; do you perceive shades of color exactly the same as other people?

Use the difference between your expectations and reality as fuel to motivate you to ever greater precision.  Read every track to the minute, hour,and day of its creation?  Sure, that’s a great expectation for a beginning tracker, probably unreachable, but a realistically ambitious goal will help one improve.

When reality tempers those expectations, beginning trackers can and probably will get discouraged.  So?  Does one quit or keep nudging?  This area offers much …  material for the illustrator, hope and improvement for the student tracker.

Accumulating experience can nurture ability, and improve precision.

The more you look the more you see, and the brain accumulates experience as one goes about their daily patterns, which that means there is learning value in just noticing tracks every day.    Grandfather Pa Jay was a Texas farmer with a huge garden, chickens, pigs, and large pastures for his milk cows.  While caring for his farm he put in dirt time much of every day, he tended to notice his animal’s tracks, observing them and the trails every day, and so was subconsciously accumulating experience at reading signs of weathering.  Eventually he was able to age tracks to the year, month and day, years later and even clear across one of his pastures … after they built that railroad track on a low berm along its edge.

Not all trackers are as lucky as Pa Jay.  Tracking can be an irregular kind of experience … Only on weekends maybe.  Sometimes precision of aging can be nearly absolute, you watched the person move down the trail,   other times you’re estimate requires a set of pretty wide upper and lower limits … the  age boundaries of fossilized tracks.  The accuracy of age estimations for current-day tracks is a little more precise.

 Ways to increase the accuracy of one’s age estimates:

Practice – track boxes can give you a controlled environment.  Regular checks give you a sense of how the weathering is going.

Photographs – well, not so much.  For some obvious signs like hail, yes.  For more subtle differences like changes in the shade of disturbed earth, it takes some knowledge of photography and lighting to capture each photograph with the same shading and lighting.  How many shades of surface color exist between wet sand and the same sand dried to the bone?  Even then, when trying to observe really fine distinctions of this sort out in the real world, natural lighting is pretty flexible, varying more than most of us realize ‘cause our brains are so visually adaptive.

Network – with other trackers about this topic.

Observe – how many tracks have you seen made, and really paid attention?

Write – pick some sign of weathering and describe it and its changes as accurately as you can.  Read your description aloud, correct it, and put that away for a few days.  Next time you think of it read it again … repeat until you can’t find any more changes to make.  Now have another tracker read it to see if it makes sense to them, or if you missed something.  You will learn from this one!

Trails have age indicators – so use them also.  You may find one clear and certain age indicator for the trail that puts everything else in its proper time-perspective.  And keep in mind that when you’re following a trail, one direction is going only further back in time, sometimes a lot.

Walking the same route –  There are drawbacks, and benefits.  For learning to read the age of tracks it can help.  Today you walk the same route as yesterday and find moose tracks that weren’t there yesterday … ?  Or, you can still see some of the tracks where, last fall, after coming down the ancient trail and crossing the road, a herd of elk left the road and descended that 45 degree slope to the stream?

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Concept Illustrated: Weathering: Changes in color shade, Wind-blown sand …

The idea: “How long ago did this happen?”…  Fortunately, soil dries and wind blows.

Different shades?  The bottom side of a stone rolled out of its bed, the earth it exposed, a wet track on rock compared to one just made with your own wet hand, or the inner surface of a track compared to the upper rim, and surrounding soil.  These, and similar signs sometimes provide a fairly accurate estimate of when a track was made, or disturbed. Though precision will diminish after a while, the accuracy can sometimes be down to minutes, or even less.   In some soils differences in shades of color can remain distinguishable for quite some time.  Reading a track’s age always imparts interesting information.

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The Other Concepts:

Page: The Concepts of Tracking… The Essentials
The Translucent Foot

Page: Foot and Body Movements … How body movement creates and is reflected in the tracks, and how to read it from them.
Canine Claw Tip Leaves Track in Fine Sand

Page: How To Find and See Tracks … Ways to reveal hard to see tracks and details
Predicting where the next track will be…
Dust Compressions (Dull on Shiny by Canine Toe Pad)
Controlling Lighting to Increase Visibility of Tracks
Track on ‘Bare’ Rock (Red Fox Front Foot)
Using Stone Rolls to Find Tracks
Lifts
The Tracking Stick
How Far Can You Go …

Page: How To Read Tracks … (and trails) – The problem isn’t lack of information
Simple Tire Track and Direction of Travel
True Track (Canine Toe Pad)

Page: The Invisible Skills … Think you’ve gone as far as you can?
Problem Solving by Baby Steps
The Only Way to Get Anywhere Else…

Page: Species … Tracks of distinct species and track features unique to them
Deer Foot – One Walking Step
Red Fox Front and Rear Feet – Side Trot

Page: Track Features … The story is revealed by the details
Pressure Against the Track Wall (Canine Toe Pad)
The Wave, Simple?
The Ridge Between Canine Front Toes
The Layer of Sand in Contact With The Foot

Page: Trails and Sign … Reading all the layers
The Human Trail

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