Rectangular Ruins - Martian Archaeology

There is also a circular depression just below the "fortress"

IMAGE SOURCE: Malin Space Systems

Aerial photograph showing the town of Amara West with the River Nile in the background

Radar, Magnetometers & Soil Resistivity Tests

Before excavation begins, archaeologists can get a peek beneath the surface with a wide array of technologies. Such instruments create a 3-D image of what lies beneath and give archaeologists a huge edge in knowing where to dig without bringing in a backhoe to tear up everything.

Ground-penetrating radar transmits pulses into the ground that reflect off buried materials, buildings and soil changes. Magnetometers detect buried artifacts based on the changes they create in the Earth's magnetic field. And soil resistivity instruments can pick up on similar buried features based on abrupt changes in electric current as it runs through the soil moisture.

Occasionally, the magnetometer or another instrument may detect an artifact or building that almost seems like a ghost signal, because archaeologists fail to find it despite digging. That points to the limits of human perception in following up on the technological leads, said David Hurst Thomas, a curator in anthropology at the American Museum of Natural History in New York.

"If we open up the site and decide to excavate, sometimes the instruments see things that we can't see as archaeologists,"
Thomas said.

Satellite images have revealed hidden streets and buildings at Egyptian sites such as Tanis.
Credit: University of Alabama at Birmingham.

Satellite Imaging from Space

Nobody from Indiana Jones' day could have imagined satellites high above the Earth helping archaeologists pinpoint the locations of buried ruins. But now, archaeologists regularly look to the visual images compiled by Google Earth to scan for their next big dig, and use radar imagery from NASA or commercial satellites to unearth hidden treasures.

Infrared satellite images have revealed pyramids, streets and palaces that lie buried in Egypt, as well as ancient rivers hidden beneath the Sahara. Such radar imagery has steadily improved over the years until it can now resolve buried features as small as 1.3 feet (0.4 meters), and as deep as 33 feet (10 meters), said Sarah Parcak, an Egyptologist at the University of Alabama in Birmingham.

Archaeologists may even someday face a time when remote-sensing technology can create detailed images of even the smallest buried objects. That could create a mild professional dilemma.
"What happens when satellite radar images have a resolution of a couple inches, and can go deeper?" Parcak said. "Will we ever have to stop digging? I hope not."

SOURCE: 10 Modern Tools for Indiana Jones