Tessera

Tessera

Fig. 7.23 . Because there is little soil and no vegetation or erosion to confuse us, we can see tectonic patterns on Venus much more easily than on our own planet. This region, covering an area of 37 kilometers wide by 80 kilometers long, is located at 30 degrees north latitude and 333 degrees east longitude, on the low rise separating Sedna Planitia and Guinevere Planitia. It shows a criss-crossed pattern of radar-bright lines, which appear to be faults or fractures. The orthogonal system of ridges and grooves is formed in elevated terrain (by 1 or 2 kilometers), and spaced at regular intervals of 1 to 20 kilometers. Known as tessarae, from the Latin word for "tiles", the features suggest repeated episodes of intense surface fracturing that may be unrelated to volcanic activity. This type of terrain is not seen on any other planet. It covers about 8 percent of Venus's surface. Sedna is an Eskimo goddess whose fingers became seals and whales, and Guinevere is the legendary Queen of the British King Arthur. (Courtesy of NASA.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University