Paleontology/Preserved Footprints Question

For starters, the way a footprint would get preserved is for it to be made in mud, and then fairly quickly covered over with another layer of sediment that would preserve it. The problem you'd have after only a century or so is that all the sediment would still be soft. It would usually take many thousands of years of undisturbed peace for the sediment to become lithified into solid rock.

An exception, however, might be volcanic ash being deposited over a bed of footprints. That would be pretty unlikely, but not impossible. Another might be prints made in a desert regime during a rare wet episode, and then allowed to desiccate undisturbed for a time. Even that, though, would have limits to preservability. I doubt something like that could survive more than a year or two.

In general, however, without quick burial, a footprint is almost certain to deteriorate into unrecognizability in a matter of weeks or, at most, months.

I'm no expert on the fossilization process, but if memory serves from Earth Science, it takes a very long time for something to become a fossil. This makes me think that under most normal circumstances, after only 100 or 150 years, the footprints wouldn't be fossils. In fact, I've got a feeling that there would be a decent chance that the prints wouldn't have even been covered by dirt, allowing them to begin the fossilization process. Of course, assuming this story is fiction, you can always make up a special set of circumstances that creates the fossils faster than they naturally would have. This also means that you could make them look however you want them to, so long as it serves the story.

Emerson said:

So if the print were made and then quickly buried, are you saying that the sediment would be too soft for the print to actually be excavated/discovered or be any use?

Click to expand...

Sorry, I didn't see the other replies. I think that blackbird is saying that the sediment would still be dirt/mud/sand/whatever, not having had enough time to turn to rock, so excavation would be near impossible. Making a cast of the print would be a much better idea. Check out the below link for information on casting footprints.

http://forensics4fiction.wordpress.com/2011/06/05/casting-footwear-impressions-in-soil/

If you need your footprint to be preserved after only a century, you could have it in nearly solid lava / volcanic ash, which then hardens pretty quickly. Some of the oldest human footprints were preserved that way:
http://www.newscientist.com/article/dn7627-footprints-rewrite-history-of-first-americans.html
http://en.wikipedia.org/wiki/Ancient_footprints_of_Acahualinca
They were still preserved under water and sediment, of course, otherwise they would have been eroded over the eons. But looking at the plaster casts of the holes left behind by the people of Pompeii makes me think that the hardening process of the ash/lava layer must happen pretty quickly (before the bodies rotted / burned / dessicated, I mean). http://www2.brevard.edu/reynoljh/italy/corpsecasts.htm

Also, this article (which I only skimmed, sorry) seems to suggest there are human footprints in volcanic ash on Hawaii, made in the 18th century and rediscovered in the 1920s:
http://www.nps.gov/havo/historyculture/footprints.htm

(And if you have a culture capable of archaeology, you'll most likely have historic records which allow you to date the volcanic erruption. Carbon dating the sediment layer would work to, I think, as long as it happened before your civilisation started their first atomic tests.)

If there aren't any volcanos n your story's setting, then you might try limestone soil and some convenient weather; clay sol could also work. If the lme or clay soil were saturaated and someone made a footprnt, then there was no rain for weeks, and the soild dried; t would be stiff and solid. Then it got covered with a different kind of soil, say sandy loam, then it could preserve its shape for a long time. if that area ceased to get wet, then it might be pretty solid a hundred fifty years later. I can imagine something like that having happened around building sites.

In the American West there are prints / tracks made during the colonization period that still show in the desert or plains - as in wagon ruts in Nebraska. In a place where there is usually no or little rain and prints were made by something heavy (so they're fairly deep) during an unusual wet spell, I think they'd still be visible 150 years later. Puma

Emerson said:

So if the print were made and then quickly buried, are you saying that the sediment would be too soft for the print to actually be excavated/discovered or be any use?

Click to expand...

Pretty much, said in maybe too many words. It's useful to think of the way crime investigators preserve footprints. They use a quick-setting plaster or similar substance to make a cast, and they need to do it fast, before the print deteriorates.

Puma said:

In the American West there are prints / tracks made during the colonization period that still show in the desert or plains - as in wagon ruts in Nebraska. In a place where there is usually no or little rain and prints were made by something heavy (so they're fairly deep) during an unusual wet spell, I think they'd still be visible 150 years later. Puma

Click to expand...

Wagon ruts, yes. They gouge deep grooves into the ground which will remain for a long time. Individual footprints, more doubtful.

I don't know.

There's a BBC show called Coast, and at one point neoltithic footprints , perfectly preserved in the mud by the banks of a river, the Severn?, were pointed out.

They weren't fossilised so the archaoloists, and there should be a g somewhere in there, could only study them when the tidal force revealed them. It may have been the Thames.

And guess who's havering?

So yes, footprints can be discerned at a later date. But it depends on the conditions.

Regards

Whacko.
I'll need to try and find a link, and I should be in italics because