This is an astonishing thing to witness. Many people are familiar with the well known sites, they have seen the temples in pictures or on a TV show, for example Tikal. These sites are commonly depicted after they have been painstakingly reclaimed from the jungle, the structures are stone colored and the paths among them are dirt brown.

What's not commonly seen is the view out from atop one of these tall structures - the chaotic green sea of the jungle canopy is punctuated by tidy triangular mounds as far as the eye can see. The landscape is littered with these structures that were once upon a time built and maintained by many generations. Weep ye mighty!

Yeah i think we are heavily underestimating how quickly nature can retake cultivated land.

This is something that has always fascinated me - just how do the processes which cover a landscape with, say, layers and layers of sediment - or jungle cover - really work?

I mean, I get it - you leave something out, a few weeks later its going to get covered in a layer of dust/sediment. But how is it that entire cities get buried under 10's of meters of dirt? I'm sure geologists have this all figured out, but it always amazes me that our world changes like this so rapidly.

In this case, I'm sure the answer is 'the jungle eats everything' .. but there are places in the world, buried under meters of sand and sediment, that I just wonder .. how does this happen ..

Leaf litter accumulates and breaks down and becomes new soil, mountains and hills erode and that sediment accumulates in lower areas, wind move lots of sand and fine sediment around, All of that piles up in places until things once on top of the soil are now buried.

It's a little more complicated than that, but that's part of the process.

Another aspect is that cities used to literally rise as they deposited waste in situ and had to build up as 1st floors became basements. This is partially the source of mounds.

Neat reddit discussion: https://www.reddit.com/r/AskHistorians/comments/17je7i/arche...

It's not that complicated. Humans tend to build in flat areas. Flat areas tend to be flood plains. When flood plains flood they leave behind sediment. There are additional ways that sediment builds up such as airborne deposits and importantly from growing plants leaving behind biomatter, but in a lot of cases flooding explains the substantial depth of sediment deposited.

It’s one of those overlooked facets of Nature. Much of the Great Plains sits on the Ogallala Aquifer. This is an underlying terrain, to depths of hundreds of meters, filled in by sediment from the Rockies (https://en.m.wikipedia.org/wiki/Ogallala_Aquifer#General_cha...).

The greater part of the LA Basin is a floodplain which consists of hundreds of feet of sediment from the San Gabriel mountains.

Yeah, same here. And some ancient cities and settlements have _layers_ below them[1]. How?

[1]https://en.wikipedia.org/wiki/Troy#Historical_Troy_uncovered

Archaeologists have characterized various layers, the depth and thickness will vary.

So a layer there might just consist of evidence of some particular activity that one settlement engaged in that earlier and later ones did not.

There are lots of depositional (and erosive) processes happening. They're all subject to local conditions. But the most common (in no particular order) are: accumulation of plant matter, flood deposits, human-generated organic and building debris, and earthworm casts. You can also see other things, like volcanic activity and wind-blown material, in fewer places.

Definitely. It's a common sight in tropical countries to see modern buildings covered in random growth foliage (gutters, roofs, pavement cracks, window sills, etc.). I'd hazard a guess that even 20 years would probably be enough to significantly hide most low-rise buildings.

In some hiking circles you see people posting pictures of basements or fallen chimneys in the middle of nowhere in a wooded area.

If you passed more than fifty feet away you might miss them.