These enigmatic rectilinear formations are found in many different areas of Mars. Their origin and development is unknown, though some workers have speculated that ice wedging may play a role.

The nature of these rectilinear formations is not well understood. Here the "walls" seem very subdued. The overlying material is very rough textured, and there are areas where it apepars the material hasn't fully "filled in."

This area of the Hellas plain appears to be icy, though there is no confirmation that the surface is (or was) ice. The difficulty with Hellas is that the air is generally saturated with water vapor and the surface is usually shrouded in fogs, mists and clouds. The origin of the flows and clouds is not fully understood.

Yet here, the "walls" are quite distinct. The overlying material may have collapsed into the "walled" areas. There appear to be flow lines through the "city" -- as if material had liqufied and flowed away to the left. If there was a flow, it hasn't significantly affected the "walls."

The image above shows Inka City-like formations in Hellas. As is the case with the South Polar Inka City shown on the previous page, these formation appear to have once been beneath the surface; erosion has stripped away the overlying material revealing the "city walls" beneath.

At right is a wide angle view of the South Polar Inka City for comparison. Note that the formation appears to be in a low valley and that the scarps around may be the remnants of an overlying surface.

The image above shows a small crater in Xanthe Terra containing an Inka City-like formation. Again, it appears that overlying material has either eroded away or collapsed into the crater. Note that the character of this terrain is quite different than either Hellas or the South Polar deposits.

The picture at right shows another "Inca City" -like formation, this time in a large basin region in Arabia. This image may provide some clues about one way "Inca Cities" are made. Here -- as is the case in many regions -- the surface appears to have been fluid at one time. The criss-crossing "walls" resemble a fluid that is being shaken. Could "Inka Cities" be the result of the surface of Mars being shaken severely, possibly as a result of impact? Could there be internal forces that can shake the surface stronly enough to cause such formations?

Click on the image to go to the USGS page for this image -- the bottom panel contains the "Inca City." Note that the bulk of the image shows the scalloped margin of a pedestal crater. Note that the crater's ejecta (assuming that's what makes up the "pedestal") is LAYERED. Is there any way that impact ejecta could be layered like this? Is it reasonable to suggest that pedestal craters may be formed by internal process as well as impact?

BUGS ON MARS

Water Signs And Dark Spots

INKA CITY