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 sloping 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
