How Come: Cities buried by disaster. . . or time

towns end up underground? Some, such as the city of Pompeii in Italy, were destroyed quickly, by erupting volcanoes. Archeologists uncovering Pompeii - buried in the year AD 79 by lava and ash from Mount Vesuvius - even discovered loaves of half-baked bread in stone ovens.

But it doesn't take a cataclysm to bury a town underground. We've all seen once-thriving neighborhood where whole blocks now stand empty. When crumbling, abandoned buildings are eventually razed, only a pile of rubble is left. Eventually new buildings may be built on the same block, on top of some of the bulldozed rubble. In a hundred years, those once-new buildings may be torn down and replaced, leaving some of their own debris behind. Future archeologists or builders, digging on the site where the most recent structure once stood, will find traces of older and older structures the further down they dig.

Digging through the layers, scientists find the remains of many ancient towns. Houses were often made of materials like dried-mud bricks, which rains and floods gradually dissolved. Falling-down houses were often abandoned and other structures eventually built where they stood. In fact, whole settlements were often deserted after famines, fires, wars or ravaging diseases, then gradually worn down by wind and water. Where plants spread over the wreck and decayed, a layer of topsoil formed, further burying the traces of a long-gone settlement.

Over thousands of years, mounds of earth (up to several stories high) and the buried stuff of everyday life may be all that remain of a long-lost town. Archeologists can often tell a town (or several towns) once flourished on a site when aerial photos show odd hills stretching across the landscape - the remains of collapsed buildings and centuries of trash.

Sometimes, governments create buried ghost towns. The hamlet of Doodletown, N.Y., was established in 1762 in what is now Rockland County. By the 1920s, Doodletown had a church, a school, stores and two cemeteries, as well as about 70 homes.

But nearby Bear Mountain State Park was busy expanding, and most residents of Doodletown sold their property to the park over the next 30 years. In 1965 the few remaining Doodletowners lost their land to the state of New York. Most of the village was razed, but the cemeteries were left intact. Today, park visitors can find a few remaining walls, staircases and the foundations of old buildings, overgrown with woodland plants.

For information about hiking in Doodletown, visit nynjtc.org/historic/doo dle town. See a buried Egyptian city revealed by satellite and radar imaging at physorg.com/news196314761.html.