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I am trying to develop a story where it is based on Earth around the 42nd century and can't figure out if the continents would have made any noticeable/notable shifts. Any help is appreciated.
Edit: I see a lot of you mentioning climate change and I was thinking that we'd be able to meditate it/reverse some of it. So the coast lines would be a little closer to home but not drastically.
Over 5,000 years, there is hardly a place anywhere on earth that a before and after picture would not show considerable, very noticeable differences. In fact, 500 years would be sufficient for visible changes to occur over most of the land masses.
But would this person notice? How good is the memory of your person? Frogs can freeze because they do not notice a very subtle lowering of the temperature. Can this person accurately remember before-after recollections of the landscape?
And could you pin-point the changes to continental drift? Perhaps, if you were an archeologist or geologist.
Weathering, erosions, earthquakes, natural disasters, forest fires, flooding, sinkholes, earth rebound, they all contribute to changes in the landscape. Without scientific knowledge, measurement, and research, can you attribute the cause? Sometimes, but not always, and not always noticeable in the short term. Places in Denmark and Venice are sinking, very observably over time because when once you had to go up steps, you now have to go down steps. In places like Toronto, Ontario where the ground is rising in rebound to the massive ice cover, the changes occur subtly in such things as broken water mains over long periods of time, and engineers need to calculate the effects when designing mega-story buildings that they hope will last centuries. But when the land is rising relatively equally, it is almost impossible to detect with the eye.
So yes the changes could be noticeable over 5,000 years, with sufficient 'memory' of before-and-after, almost anywhere on earth, but allocating the changes to 'continental drift' would be a task for experts using expert measurements.
EDIT Addendum
As Greenland loses more and more snow load due to melting and climate change, the entire Greenland plate is rising. Over 5,000 years, the changes in plate positions due to climate change could be very significant, and in places very noticeable. Site lines, for instance, could change. Landscape features in the distance could either become visible or could sink below the revised horizon, but this would be localized.
EDIT Addendum 2
As the Five Gorges hydroelectric project in China filled up, GPS algorithms heeded to be updated with the new information. The Earth's gravity and rotation was altered that significantly. Although not due to plate tectonics, it highlights the difficulty in attributing the cause of shifting landscape consequences to any particular factor without extensive measurements and scientific investigation. Had engineers not done the calculations, the GPS system would have produced inaccuracies that were significant and very noticeable. That is, even subtle changes in the Earth's shape can be significantly amplified by our level of 'precision technology' and thus become very noticeable even to casual observers who are dependent on that technology. They might not know why, or how everything moved, but they would know that 'today' did not match 5,000 year old GPS data and GPS maps. This is a 'memory' thing. Do they have access to 5,000 year old data?
Over a period of 5,000 years, all coordinates and mapping dependent on GPS navigation would have to be significantly updated to maintain the precision of GPS. Putting up a fence 120 meters from where it should be due to continental drift because GPS information and mapping had not been updated for 5,000 years would be very noticeable, and most surveying today is GPS based. "Dang, I am sure that cliff used to be over there on my GPS navigation!!!!!"
Continental plates move at a rate of few cm per year. That makes few meter per century, and in 5000 years, that is 50 centuries, would account for something like 50-100 meters.
Even for close continents like Europe and Africa that would be less than 0.1% difference.
Not enough to be noticeable with just human senses, I guess, especially for distances which we cannot cover in a single sight.
With sensitive instruments it would be noticeable, instead. Just having a cable laid across the two continents (a telephone cable, for example) would make noticeable that there has been a shift (assuming that the cable survives 5000 years).
While continental drift may be reasonably "unnoticeable" as per L.Dutch's answer, natural erosion processes won't be.
There are known settlements that existed in the last 2000 years that are now lost to the sea due to erosion. As in the cliff face is further inland, and the cliff settlement isn't buried but actually fallen and lost into the sea!
Another visual example are the light-houses and beach houses that are considered "national treasures" built on the sea front having to be relocated to avoid falling into the ever encroaching sea! They are only 200 to 300 years old. (Just google "relocating lighthouses" and several documentaries on the process will pop up!)
Depends where you live
The following picture of Birling Gap, not far from where I live, shows a row of houses. When they were built, they were a long way from the cliff edge. What you see now is only half of the houses - the rest have fallen into the sea.
You can see the original setup in the following picture. The red circle shows the house that is currently nearest the edge.
How long did this take?
This has all happened within less than 120 years. Birling gap before and after
What is the reason?
The mainland of Britan is disappearing under the continent of Europe. If you are lucky enough to live on the West coast of Britain, there is a good chance your property will get bigger as time goes by. If you live on the East coast, don't stay away from home too long!
Yes, no and many many times maybe.
The human brain is marvelous, adaptive, forgets not relevant details, learns new things, shifts perspective on all things it has ever learned - and holds onto unconscious biases, tweaks others into a new perspective. Distorts perceptual details in memory according to wishes, desire, regrets and societal pressures - not to mention changes in biological functioning.
It might notice changes, it might notice changes even when they haven't happened over such scales as to be relevant to you story - it might notice and then forget. Over and over again.
Tough question considering the vagaries of the human brain.
Yes you absolutely would notice
You wouldn't notice that America was getting further from Africa by eye - you couldn't see that far anyway.
However continents are grinding away at each other and internally all the time. If you lived here, a hundred years would be enough to see a big change. A thousand and the road would have to be re-shaped.
California’s Hayward Fault is considered one of the most dangerous seismological zones in the United States ... Technically speaking, the Hayward is a right-lateral strike-slip fault. This means that it shows its everyday action in the form of aseismic creep, the slow, steady sliding of land along the fault’s margin. The symptoms of this tectonic origami are visible across the region—in cracked asphalt, off-kilter curbstones, and leaning walls. https://www.newyorker.com/tech/annals-of-technology/creep-on-the-hayward-fault
Here is a mathematical answer
The North American and Eurasian tectonic plates, for example, are separated by the Mid-Atlantic Ridge. The two continents are moving away from each other at the rate of about 2.5 centimeters (1 inch) per year. https://www.nationalgeographic.org/encyclopedia/continental-drift/
5,000 x 2.5 cm = 125 metres
No-one apart from a professional would detect that difference. However plates move laterally to one other along fault lines. If you started living directly across the road from your friend with a fault line in between, you would definitely have a longer walk to their house after 5,000 years.
In certain locations, you could. Thingvellir valley in Iceland is the rift between the North American and European plates.
This valley widens about 2.5cm a year. Over 5000 years, with constant movement, it would widen 125 m, certainly a noticeable difference.
The valley has widened by 8.5 m since Iceland was settled 1150 years ago. This widening is somewhat less than the estimate above, but it is not trivial.
TL;DR: Yes, if you live in the right location. But it won't change travel time.
Source: https://icelandmag.is/article/9-essential-things-know-about-thingvellir-national-park
Most answers assume think about continents moving horizontally.
However, there have been significant vertical movements of parts of the continents during the last 5,000 years in parts of the world due to climate change, in particular the land in Scandinavia and Canada rising after the latest ice age. (Continents move slowly.)
Even if just a few mm/year it still changes the coast-lines noticeable and this rebound is expected to continue 10,000 years into the future (even in the unlikely case that the climate doesn't change). https://en.wikipedia.org/wiki/Post-glacial_rebound
Once in a while you get blatantly obvious movement. In 1906, the San Andreas fault ruptured and experienced multiple feet of displacement in a single movement. From this NPR story
At the Point Reyes National Seashore in Marin County, California, a short trail takes visitors to this displaced fence, showing an 18-foot gap, one of the largest offsets found after the 1906 quake.
Another place in antiquity where people knew something had changed in a single instance was in the Pacific northwest (near modern Seattle). There's the Juan de Fuca plate that is a subduction fault. In subduction earthquakes, the land is bent by the tectonic stress of the plate being pushed beneath. When that fault ruptures, the land itself sinks (and it produces catastrophic tsunamis). In this case, a lot of coastline disappeared overnight (along with likely hundreds of Native Americans killed in the quake and tsunami).
The earthquake also left unmistakeable signatures in the geological record as the outer coastal regions subsided and drowned coastal marshlands and forests that were subsequently covered with younger sediments.
New Zealand and Taiwan both have grid datums that move fast with time, as the land masses drift with tectonic plates, so that GPS positions taken 10 years ago are now inaccurate, unless you have an accurate model of the movements.
If you had a GPS still working in 5000 years in New Zealand in some areas, you would be going to a position maybe 200 yards/metres from the original position. A cache of buried material would not be where you surveyed it for instance...
It is a factor in geophysical surveys taken over time.
As others say, with big earthquakes, things move metres in a big jump, the 2011 Japanese earthquake moved 30 to 40 metres in one go out at sea.
Over 5000 years even the fastest-moving bits would only shift by 500m or less.
The apparent shift of coastlines, widening of canyons, deepening/shallowing of waterways due to erosion will be much, much more visible and will likely swamp out any evidence of actual continental movement.
Not to mention how the sealevel bounces up and down over that sort of timespan.
The 2011 Tōhoku earthquake in Japan (the one that triggered those nasty Tsunami's)
moved the land by some 5 meter eastward. Which required GPS maps of the region to be updated!
It also sped up the Earth's rotation a bit, making days shorter by some 1.8 microseconds, which also affects GPS everywhere. Such changes are routinely updated into navigation databases.
For the reasons others have listed, yes it is noticeable, easily measurable. Yes modern people would be aware of it due to modern measuring capability and record keeping, as they are aware of it now.
But, an immortal human that can remember things thousands of years ago as well as we remember things in a normal life span would be unlikely to attribute this to continental drift in the course of 5000 years unless they were specifically interested in detailed cartography. People of normal life spans wouldn't be much assistance, unless they had similar advancements to the ones we use to measure or track it today.
To someone not paying a great deal of attention, the houses falling into the ocean, sidewalks slipping, cracks widening, etc would be attributed to their immediate, flashier causes like erosion, volcanic activity, and earthquakes. Even if they traveled across the country for 5000 years and noticed that the cliff was receding slowly, that some cities have had to realign their streets 50 times in their life, and that massive cracks open in the earth and get wider, that the mountains get taller, it's unlikely that someone with no compelling reason to sit down and draw a map of which direction things are creeping would figure out the underlying cause of the seemingly unrelated ground-movement events.
