area. Eruptive vents on the western edge of the field formed along a fault line that trended to the northeast, located north of present-day Carver. Boring Lava was erupted by vents in the volcanic field, and it has been exposed at elevated topographic levels in intact volcanic cones and dissected lava plains. There is likely more lava deposited under Quaternary sedimentary mantle throughout the region, though activity was confined to a relatively concentrated area. Subfeatures D. E. Trimble (1963) argued that the Boring Lava Field was produced by eruptive activity at 30 volcanic centers; these include shield and cinder cone volcanoes. J. E. Allen reported 95 vents in 1975, dividing them into four clusters: 17 vents north of the Columbia River, 14 vents west of the Willamette River, 19 vents east of the Willamette River and north of Powell Valley Road, and 45 vents east of the Willamette River and south of Powell Valley Road (Highway 26). Of these, 42 were unnamed, and several volcanoes contained multiple vents. Generally, all lava flows in the field can be traced to specific vents in the field, but documented source vents have mostly been confirmed through chemical analysis or petrographic comparisons, with a few exceptions. In the eastern part of the Boring cluster, volcanic vents have average diameters less than , with average heights less than from base to summit. The lava flows from Highland Butte and Larch Mountain, both shield volcanoes, encompass a wide area, the Boring Lava deposits averaging thicknesses of not considering areas next to volcanic cones in the field. Most of the summit craters have been destroyed, though there are partial craters at Bobs Hill (located northeast of Portland) and Battle Ground Lake (located north of Portland); Mount Scott also has an intact summit crater. However, many of the Boring vents retain the shape of a volcanic cone, with loess extending above an elevation of . The Rocky Butte plug, which reaches a height of above its surroundings, was dated to 125,000 ± 40,000 years old by R. Evarts and B. Fleck from the United States Geological Survey (USGS). Mount Tabor is also prominent in the area, dated by the USGS to 203,000 ± 5,000 years old, as are Kelly Butte, Powell Butte, and Mount Scott. Scott has been dated to 1.6 million years ago. A series of lava tubes were documented near the Catlin Gabel School along the