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<br />Three hazard zones are identified for this fan. The flows appear to be <br />more frequent at the apex and in the area from the northernmost major channel <br />to the southernmost edge of the fan. Therefore, this area is placed in <br />the Very High Hazard Zone. An area of High Hazard covers the lower portion of <br />the fan. There is probably some mud- and water-flooding at the outer edge of <br />the fan where a small band of Moderate to Low Hazard is mapped. <br />Corbett Creek: Several events have been reported on Corbett Creek in the <br />recent past. The Corbett Creek fan differs from the other fans studied in <br />that it has formed an elongate depositional lobe along the north side of the <br />fan where the creek presently runs. This appears to be an area of intense <br />activity. The channel has also become incised at the apex of the fan. It <br />appears that the entrenchment of the stream at the fan head is preventing <br />deposition on the upper fan and causing deposits to form on the middle and <br />lower parts of the fan, thus creating the lobate area. Judging by the history <br />of other debris fans, the creek will probably tend to build-up this area <br />before spreading out onto the main part of the fan again. This could be <br />accomplished by one or two large events. <br />Examination of the elongated active area showed large debris lobes, <br />levees, and severe tree scarring and burial (Figs. 26, 27). Tree scars <br />indicate that debris flows up to ten feet in depth have come down the channel <br />(Figs. 28, 29). Boulders two feet in diameter were found lodged between trees. <br />Even though the last reported event on Corbett Creek was in 1971, <br />evidence on the fan indicates that some debris flooding occurred around 1981 <br />or 1982. Small maple trees, four to five feet in height, were found, with <br />abraded trunks and partially buried. <br />It should be noted that the profi]e of the truncated edge of the fan <br />indicates that a very large debris-flow event would probably cross the river <br />and overrun the road. At present, the edge of the fan has been eroded by the <br />Uncompaghre River, which abuts the cliffs on the opposite bank. <br />Based on the location of the debris lobes, levees, boulders, channels, <br />and tree scarring, three zones were distinguished on the Corbett Creek fan. <br />The apex of the fan, its northernmost portion, and most of the lobate area, <br />were all placed in the Very High Hazard Zone. The lower portion of the fan <br />-43- <br />