Free Republic

Mima Mounds: Scientists say new laser maps suggest glaciers as the architects of the mysterious humps, but one gopher proponent holds firm. From goofy to erudite, more than three dozen theories have attempted to explain the origins of grassy mounds that dot the prairies of Southwest Washington. The latest twist won't settle the debate, but it casts the mysterious hummocks in a different light. Laser light, that is. Scientists used airborne laser surveys to create topographic maps that reveal new details about the so-called Mima Mounds scattered across lowlands south of Olympia and Tacoma. The technique fires 23,000 pulses a...

The bustling harbour of Altinum near Venice was one of the richest cities of the Roman empire. But terrified by the impending invasion of the fearsome Germanic Emperor Attila the Hun, its inhabitants cut their losses and fled in AD452, leaving behind a ghost town of theatres, temples and basilicas. Altinum was never reoccupied and gradually sunk into the ground. The city lived on in Venetian folk tales and historical artefacts but its exact position, size and wealth gradually faded into obscurity. Now, using aerial photography of the region, Italian archaeologists have not only located the city, but have produced...

A successful Falcon measurement flight was performed on 19 April 2010 for probing plumes over Germany from the Iceland Eyjafjallajökull volcano eruption. Layers of volcanic ash were detected by Lidar and probed in-situ with aerosol instruments. Under suitable viewing conditions, the ash layer was visible as a brownish layer to the observer. The horizontal and vertical distributions of the volcano layers were variable. In the plume layers particles larger than 3μm were detected at concentrations, not present in the free troposphere during unpolluted conditions. The concentrations of large particles measured in the volcano layers are comparable to concentrations measured typically...

For a quarter of a century, two archaeologists and their team slogged through wild tropical vegetation to investigate and map the remains of one of the largest Maya cities, in Central America. Slow, sweaty hacking with machetes seemed to be the only way to discover the breadth of an ancient urban landscape now hidden beneath a dense forest canopy. Even the new remote-sensing technologies, so effective in recent decades at surveying other archaeological sites, were no help. Imaging radar and multispectral surveys by air and from space could not “see” through the trees. Then, in the dry spring season a...

Enlarge ImageUnmasked. Aircraft LIDAR sweeps found this previously hidden impact crater in central Alberta, Canada. Credit: Herd et al., Geology Researchers have uncovered a pond-sized crater in the woods of central Alberta, Canada, carved out by a meteor that slammed into Earth about 1100 years ago. The technique they used to pinpoint the pit--a laser take on radar--figures to help scientists find evidence of hundreds of similar impacts that have remained hidden until now. Every 10 years or so, a sizable chunk of asteroid or comet crashes to Earth, leaving a crater about 40 meters wide. The remnants of...