As to what's beneath us, some answers have been provided by scientific exploration. The outer crust of the earth, for instance, is not the same in every place, but in general is about 25 miles deep on land and only one-fourth that much under the ocean floors.
It's the soil of this crust that the Creator prepared to nourish trees and other vegetation and in which vegetables, fruits, grains, etc. grow. At various depths, but still within the crust, coal, oil, minerals and gems are found in abundance, indicating how liberally He has provided for generations before us, ourselves and those generations that may come after us.
Below the crust is a layer about 2000 miles thick called the mantle. This is thought to be where big earthquakes start as well as volcanoes that break right through the crust and release their fire, steam, smoke and ashes from mountain tops. Such forces have been known throughout history, and we are aware of them in our present time, too. Mount St. Helens in Washington State was an example, as well as constant eruptions on the Island of Hawaii. Frequently we hear of disastrous earthquakes in South America, Mexico, Asia and other places. There is no sure way to tell exactly where or when any of these things may take place again.
Finally, at the center of our earth is the core, thought by some to have a cover of molten metal over 1000 miles thick surrounding it, but they think the great core itself is made of solid iron or nickel or a mixture of both. However, this is just a guess and something only the Creator knows.
Volcanoes, earthquakes, strong winds and rain do make some changes in the surface of the earth, but they are not of too much consequence. The world will remain essentially the same until, because of man's sinful departure from God, His judgment will fall on it. That is the time the Bible speaks of: "But the day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up." 2 Peter 3:1010But the day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up. (2 Peter 3:10).
Before that judgment comes, He will take to heaven all those who know the Lord Jesus as their Savior, but the awfulness of hell will be the destiny of those who have refused His love. Later He will recreate the world in unspoiled beauty where sin will never mar it again, but those who have refused the Savior's love will never see this new beauty.
These are true and serious thoughts. Are you sure your eternity will be in heaven?