Figuring out when a track was left (aging it) is a fundamental and useful tracking concept. Some causes and effects of weathering, and reading them for age, are discussed here to facilitate more complete illustrations of this concept.
Accurately locating the track or trail in time provides useful information, and moves the tracker an important step closer to understanding interactions within the natural community. People lost outdoors have been rescued alive because a team of skilled trackers identified and followed the most recent part of that person’s trail.
“weathering“: the changes in a track during its existence. The causes of weathering are both external environmental events and the physical properties of the particular substrate a track is created in. Among the external events are: earthquakes, gravity, other beings, and weather. The physical properties of the substrate a track is created in determine how it responds to the causes of weathering. For example; wet sand makes castles, forget even trying that with dry sand, and sand stone doesn’t hold some tracks very well.
The effects of weathering can include change in appearance, contents, shape, and even composition (dinosaur tracks left in mud or clay have metamorphosed into stone). A few other 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.
Everything is always weathering, and those changes always follow the laws of physics, and chemistry, including both the track and the undisturbed soil around it, with differences. There is never a time when something is not weathering.
“aging“: the process of change in a track over time, or the activity of estimating the age of a track. Estimating age involves examining the signs of weathering in and around the track and trail, and using that along with any other pertinent information to deduce the age of the track.
Unless altered or removed, the signs of weathering are always present, the other ways to age tracks may not be. Except for sightings, tracking collars, and trail cameras, weathering generally provides the most precise timing information.
How long are tracks useful?
For as long as they exist, which can be millions of years, or longer. There is current scientific interest in fossilized tracks, “Neoichnology”. Scientists developing this discipline are employing all the relevant tools of modern science to interpret these tracks, gleaning as much information as possible about the animals, their behaviors, and estimates of their age.
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. Science 296, 1112 – 1115 (2002).
An example of the skills required …
We may already be using tracking skills we don’t realize we have. From life experience most of us read some signs of weathering. You’ve noticed the damp spots left by the first few raindrops? The puddles after the rain, and the mud exposed as that water evaporates, and maybe what later raindrops and feet did to that mud?
With the right kind of focus, helped along by learning materials shaped to foster it, how hard would it be to figure out how the mud alters with age? Drying to a particular shade of gray, beginning to crack? In the photo below how long might you guess that mud has been uncovered? And which came first, the muskrat or the second rain? Does the right-most track answer that question? Were all raindrops the same size? Was it even rain that made those craters?
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. (if you find a mistake, disagree with any of this information, or think there even might be 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 time-related changes to, and in the area of a track to reach an estimate of when that track was made.
The signs of weathering are only part of this process, but one of the most useful because they are always happening, always present, and one can estimate how long those changes took to reach their present state. Other factors are considered as well; anything else that can affect the animal’s behavior such as the timing of local weather events, the animal’s usual behaviors, and even changes in soil compression within the track.
“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.” (source:https://en.m.wikipedia.org/wiki/Consolidation_(soil))
A simple example of aging tracks;
– In the morning you cleared an area of ground and fluffed it up with a rake.
– Planning to keep your toes, you focus on the mower as you trim the lawn that afternoon. The lawn mower scattered grass clippings all over the place.
– The next morning you’re out enjoying your mowing job and remember that track patch, so you go check it. Most of the grass clippings have dried, and their color changed. A house cat left a trail across your fluffed up earth, and the grass clippings that fell into its tracks look undisturbed. Of the grass clippings in the raccoon tracks, some have been bent, others pressed into the soil. The raccoon tracks appear crisper, the edges more sharply defined, and some of the disturbed soil a shade darker than similar areas in the cat tracks, oh, and someone stepped in one of someone else’s tracks.
– You’ve got a rough time frame, you know when you created the track patch, and you can narrow that down even more because you know when you mowed the lawn. So you know roughly when the two animals crossed the area. 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?
There are slow and persistent influences like gravity and time. Cyclical effects like sunlight, and faster and less subtle events like tsunamis, or meteor strikes, and a bunch of other stuff in between those extremes.
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., because 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 set of rules.
The signs of weathering one looks for?
A few are: changes caused by rain, the degree of edge crumbling, 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. You reach a stream and find tracks.
– 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?
– Would the increased humidity beside the stream slow evaporation of wet tracks?
How does one interpret the signs?
Noticing the signs is the necessary first step. Interpreting them is fun. That makes the next waypoint learning what signs mean, what causes them, and how they change over time. Questions usually help (they’re also a good source of material for illustrations). “Why is that different?” is frequently fruitful.
For example: would there be any differences in how the broken end of a living twig weathered in late spring, if a moose browsed off the rest, or a lost hiker tore it off while blundering through? Maybe a different break, but same rules of weathering, right? But does moose saliva affect the weathering of the exposed parts of twig, how long does the bark stay damp?
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 in soft soil looks pretty fresh, as does the color shading of the substrate in the track. But there’s a slightly more sharply defined bird track, maybe robin-sized, crumbling one edge of the deer’s track. When do robins usually start foraging?
Causes of sign
Once you’ve noticed the signs for the first time you will begin to find clues for the causes, and can begin to decide out how fast the changes probably happened.
Variations in the same kind of sign
The variations specific to things that cause weathering are helpful. Take wind as an example; in what ways might wind 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 more complex but may be more helpful. Did the wind blow from the south all day, were there strong downdrafts just before that thunderstorm almost happened?
The processes of weathering obey the same laws of physics as everything else, and that’s very good news. 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 mentioned before can be a real help.
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 for 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 you predict that 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, there’s an observable difference in some of the tracks. But, since Murphy’s laws only work when you don’t want them to, of course the tracks don’t all match your prediction. And this is when the learning happens, you ask yourself, “Why are some different from what I predicted?”
Think a track’s location can’t change? There are lake beds that still preserve tracks of dinosaurs. Over the millions of years, how would a lake bed change in location, elevation, or tilt, as the various geological processes change the surrounding land into mountains?
Precision of age estimates (how close you can resolve the timing) … Expectations and reality
Precision of an age estimate can vary, 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?
The difference between your expectations and reality can be 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 if that was modified to a realistically ambitious goal would it 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 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 cows. While caring for his farm he put in dirt time every day. He tended to notice his animal’s tracks, and by observing them every day, he was subconsciously accumulating experience at reading the age of tracks. Eventually he was able to age tracks to the year, month and day, years later and even clear across one of his pastures … and got real good at it after they built that railroad along its edge.
Not all trackers are as lucky as Pa Jay. Tracking can be an irregular kind of experience … Only on weekends maybe, or sometimes precision of aging is nearly absolute (you watched the person move down the trail), and other times you’re estimate requires a set of pretty wide upper and lower limits (the age boundaries of fossilized tracks).
Which is all to say, “Just observing tracks, whether you can read them or not, is a useful learning tool.”
Ways to increase the accuracy of one’s age estimates:
Practice – track boxes give you a controlled environment. Regular checks of the state of tracks you made there give you a sense of how the weathering is going, what the signs are.
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, lighting, and color tones. 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.
Drawings – yes and no, yes if you’re illustrating some weathering-related feature.
Network – with other trackers about this topic.
Observe – how many tracks have you seen made, and really paid attention?
Patterns – of tracks. Fred and Wilma are walking slowly down a flat road covered by 1/2 inch of new snow. Wilma is explaining some complicated thing to Fred, who likes to be sure he understands so he asks lots of questions. Fred likes to look you in the eye, so he stops and turns a little towards Wilma every time he asks a question, the resumes his direction of travel. Each time Wilma slows, and then chugs right ahead explaining her way down the road.
Write descriptions – pick some sign of weathering then 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 can 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?
Concept Illustrated: Weathering – Changes in color or a shade, wind-blown sand …
The idea: “How long ago did this happen?”… Fortunately, soil dries and wind blows.
Different shades? The edges and bottom of a stone rolled out of its bed, the earth it exposed. 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, and 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. But soil location and shade can be affected by wind, how does that work?
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Concept Illustrated: Weathering – 24 hours in the life of a track …
The idea: A track changes constantly, even left un-disturbed. More so when layered beneath a fresher track. Even if one could sit there observing the significant changes for 24 hours straight, wouldn’t the gradual nature of some weathering and aging processes make them almost invisible to the mind?
And isn’t learning to observe these kinds of changes one of the must-succeed-at challenges in becoming able to age tracks? Would it shave time and error off the learning process of track weathering if one could help the mind learn to observe these kinds of changes by compressing them into an easily viewable time frame, emphasizing the significant ones?
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