Presented here are the results of a study of geological hazards conducted in Canyon Lake Gorge of Central Texas. Canyon Lake Gorge formed in 2002 when the emergency spillway of Canyon Lake was overtopped. Since that time, the gorge has been opened to public tours, and the organization governing the gorge has expressed concern regarding visitor safety. The surveys in this study gathered data through field observations and supplemented those data with non-destructive tests from an impact test hammer. The goal of this study was to gather original field data on potential hazards of the gorge with the hope that insight from these data could be used to enhance visitor safety in the gorge. The field observations made in this study identified the presence of undercut rock ledges that could present varying degrees of risk to visitors. Easily eroded clayey wackestone facilitated formation of these potential hazards. Lithologies such as packstone and grainstone serve to form ledges atop the wackestone. Preexisting fractures and joints in the ledge forming rock, which compound the danger of the unstable masses of undercut ledges, provide failure planes. This study identified current areas of unstable masses by location and differentiates the degree of risk present at each location, using simplified classes of low, medium, and high risk. Level of risk was determined primarily by the potential injuries incurred. Often, the height was dependent upon the thickness of an easily eroded wackestone bed that undercuts ledge forming rock. Canyon Lake Gorge is a young and dynamic geomorphological environment seeking equilibrium through gravity facilitated erosional events. In time, natural formation of riser beds will mitigate the potential hazards of some undercut ledges. Based on the potential hazards identified in Canyon Lake Gorge, four safety recommendations are proposed: - Visitors should always be guided by trained personnel. This practice is in place. - Visitors should be educated on the dangers of Canyon Lake Gorge before entering. - Unavoidable hazards should be evaluated for ways to mitigate risk. - The gorge should be continually monitored to insure safety of the visiting public.

Thèse (M.Sc.)--Université Laval, 2008. / Titre de l'écran-titre (visionné le 12 janvier 2009). Bibliogr.

Σκοπός της εργασίας είναι η καταγραφή των κατολισθήσεων στο φαράγγι του Βουραϊκού ποταμού και η ανάπτυξη βάσης δεδομένων κατολισθήσεων. Η περιοχή του Βουραϊκού αποτελεί εθνικό πάρκο, καθώς έχει μεγάλη γεωλογική, βιολογική, αισθητική, γεωμορφολογική και οικοτουριστική αξία. Η αναγνώριση και καταγραφή των κατολισθήσεων έγινε με την εφαρμογή του Google Earth, την εφαρμογή απεικόνισης δορυφορικών εικόνων υποβάθρου της Κτηματολόγιο Α.Ε. και του γεωγραφικού συστήματος πληροφοριών ArcGIS. / The purpose of this work is to record landslides in the canyon of Vouraikos and to develope a landslide database. The area of Vouraikos is a national park, as it has great geological, biological, aesthetic, geomorphological and ecotourism value. The identification and registration of landslides was done with the implementation of Google Earth, the satellite imaging application background image of Cadastre SA and the geographic information system ArcGIS.

The seasonal variation of wind speed fluctuations is studied at four locations in The Dalles area of the Columbia River Gorge. Three of the sites are located in or near the valley floor while the fourth site is on top of a 900 m (3000 ft) ridge just north of The Dalles. The speed fluctuations or gustiness at these sites varies with terrain roughness, wind speed, and atmospheric stability. Due to the channelling effects of the Gorge, wind flow in The Dalles area is predominantly upriver or downriver. Strongest winds occur from the west at all four of the sites that were analyzed. Highest gustiness values occurred at the Martin Marietta site located near the rugged foothills of the eastern slopes of the Cascade Mountain Range. Moderate gustiness values were common at KCIV located on the top of the ridge north of The Dalles and at the D.C. Test Site surrounded by rolling hills. Smoothest flow was found along the relatively level valley floor at The Dalles Dam. Gustiness in relation to wind speed varied at all four sites. Gustiness values increased with speed through the moderate speed range at KCIV while gustiness decreased with speed at The Dalles Dam and the Martin Marietta site. No distinct relationship was found at the D.C. Test Site. At KCIV changes in gustiness are directly related to the amount of solar insolation and hence the atmospheric stability. Gustiness values were highest during the summer and daytime values were greater than those at night during both winter and summer. In contrast, at the other three sites near or on the valley floor no distinct relationship between the stability variations and the changes in gustiness could be found. Results indicated that the gustiness values during the winter at these three locations exceeded those during the summer. It appears that the unstable nature of the post frontal wintertime air mass is responsible for the strong and turbulent northwest flow. Although moderate speed fluctuations were common at KCIV, this site is the most appealing of the four locations for wind power generation due to the persistency of moderately strong winds during both summer and winter. Least attractive of the four sites is Martin Marietta where high gustiness values along with weak winter winds provide little usable wind energy. / Graduation date: 1977

Thesis (M.S.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains x, 106 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 92-93).

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains vi, 45 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 41-43).

Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes folded map. Includes bibliographical references (leaves 101-110). Also available via the World Wide Web.

Thesis (M.E.S.)--Baylor University, 2006. / Includes bibliographical references (p. 112-114).

The purpose of this study was to produce a detailed geologic map of the CRBG in the western portion of the Columbia River Gorge (fig. 1). The objectives were (1) to identify and delineate the extent of the Priest Rapids Member and Pomona Member intracanyon flows, and (2) to define the relationship of post-CRBG units to the CRBG intracanyon flows.

Between October 9, 1991 and October 16, 1991 a fire burned 577 hectares in the Columbia River Gorge near the west end on the Oregon side. All of the area burned consisted of second growth Pseudotsuga menziesii and the accompanying understory. This was the first disturbance of this magnitude in this part of the Columbia River Gorge since 1902. The purpose of this study was to examine the pattern of understory recovery in the first two years following the fire. This study also sought to learn: 1) how Pseudotsuga menziesii seedlings are recruited into the population, 2) how quickly the litter layer is a reforming, and 3) how quickly snags and downed logs are recruited into the understory. Four 800 square meter circular plots were established within the burned area of the Columbia River Gorge. Two plots were designated sun plots since the fire had killed the overstory. The other two were designated shade sites since the canopy over them was still intact. Twenty five randomly placed sample units (20 x 50 centimeters) were placed in each main plot. The plots were then sampled at approximately onemonth intervals from May through September of 1992 and 1993. The frequency and percentage of cover was recorded for all plant species that occurred in each sample unit. The data from 1992 and 1993 were compared by date of visit and type of plot, either (sun or shade) using the Pearson Goodness-of-Fit Test to examine and compare differences in the extent of cover and distribution of understory species. No significant differences were found. An increase in species richness and relative abundance of understory species was noted between pre-fire data collected by the US Forest Service and what I found. However, statistical analysis was not possible because of the limited data collection in the pre-fire sample.