The only thing strong enough in Biblical times to lift valleys and level mountains was an earthquake. The people who read Baruch and Isaiah had plenty of experience with earthquakes. The Dead Sea and Jordan River Valley lie in the northern end of the Rift Valley of Africa, where the earth's tectonic plates are still colliding and scraping. It has gigantic earthquakes that level mountains and drop land into valleys and into huge lakes, such as Lake Victoria. It has huge volcanoes that build up the land into vast plateaus.
Livestock is swallowed up into the earth.
River courses change and springs dry up in one place but open up in another. Lava can spew out of fissures. Land is created and land is destroyed. They would re-establish the Kingdom of Judah under God. Now when the Israelites left Egypt, and left the wilderness to enter the Promised Land of their ancestors Abraham, Isaac and Jacob, they found that it was not going to be easy.