Tonight I was attempting to create a graphic for a post I'm going to write tomorrow evening on one of the LPSC abstracts about Io, but I don't think the above could wait. The two frame mosaic above was released as a strip of images in an image release in May 2000 by the Galileo imaging team, but I never could really SEE the steep slope until now. All it took was rotating the images 90 degrees...
The mosaic at left shows a portion of the northeastern margin of Chaac Patera, a volcanic depression on the anti-Jupiter hemisphere of Io. Click the image for a full-resolution version. The terrain to the upper left is the hummocky plains that make up the upper level of the depression Chaac sits in. The terrain to the lower right is the floor of Chaac Patera, consisting of overlapping, thin silicate flows. The margin itself is quite steep, with slopes approach 70 degrees on the right hand side. On the left hand side, mass wasting has produced a two-tone talus apron at the base of the slope. This mass wasting seems to be the result of more extensive slope failure (see the broken off section of massive lava on the far left edge of the image).
It is getting rather late for me, almost 3:30am so I will continue the discussion of this mosaic tomorrow.
These images were taken during the Galileo spacecraft's February 2000 flyby of Io. The pixel scale is 7 meters per pixel.