MAGELLAN PROJECT OFFICE

                             P-38811
                             8/12/91

Two unusual volcanic domes are shown in this Magellan full-
resolution mosaicked image.  The image covers an area 180 by 240
kilometers (120 by 160 miles) centered at 18.1 degrees north
latitude, 303.52 degrees east longitude, just east of Beta Regio.
The dome in the south center of the image is about 45 kilometers
(30 miles) across, with a 20 kilometer (13 mile) caldera, or
volcanic collapse crater, in the center.  The dome in the
northwest corner of the image is about 30 kilometers (20 miles)
across with a small (5 kilometer or 3 mile) summit crater;  the
very bright radar return from the western flank of this dome
indicates that it has steep slopes.  The flanks of these
volcanoes display prominent gullies which may have been formed by
slumping of surface material or thermal erosion by lava flows. 
Variation in the brightness within the surrounding plains show
the extent of lava flows which originated at these volcanoes. 
Arcuate fractures surrounding the southern edifice indicate that
there has been subsidence (down-warping) of the dome following
eruptive activity.

                    Jet Propulsion Laboratory
               California Institute of Technology
          National Aeronautics and Space Administration
                     Pasadena, Calif. 91109