Another haunting discovery are the so-called hunger stones that are once again visible in the river bed of the Elbe near Decin in the Czech Republic. Inscriptions - likely from the 15th century - tell of a severe past drought and the famine it caused. The quote "If you see me, weep" is a stark reminder of the power and the horror of natural disasters.
In Spain, the Czech Republic, Italy, Iraq and China, sites of historical value are once against visible - some of them dating back to Roman times or even the Bronze Age.
A new discovery is probably the oldest of the bunch: At Dinosaur Valley State Park in Texas, fossilized dinosaur track that are estimated to be 113 millions years old emerged from a dried-up riverbed.