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Mount Baker Crater Steams Caves By Dr.Engene Kiver, Charles H. Anderson Jr., Dr. Mark Vining International Glaciospeleological Survey Mount Baker, Washington Location: 48.79N, 121.82W History Mt. Baker is an isolated stratovolcano in northern Washington. It is the northern most of the Cascade volcanoes in the United States. Most of the summit of the volcano is covered by glaciers. Because of this, the Indians gave Mt. Baker a name meaning "White Steep Mountain." Mt. Baker has been very active over the last 10,000 years. Over that time it has had one pyroclastic flow, at least four small tephra eruptions, at least two lava flows and at least eight mud flows. Mud flows remain the largest hazard on Mt. Baker. Mt. Baker erupted in 1843. This eruption resulted in the deaths of many fish in the Baker River, a large forest fire, and the dropping of volcanic ash. The release of steam occurred at Mt. Baker in 1975-6, but no eruption followed this event. One of the most recent formations on Baker is a ~2500 ft (~760 m) wide, ~330ft (~100 m) high cinder cone and its ~7 mile (~11 km) long lava flow at Schreibers Meadow. Mt. Baker has erupted 13 times in recorded history. Its last eruption was in 1880. The modern summit crater probably formed about 8000 years ago and has subsequently ejected only small amounts of pyroclastic material (Jack Hyde, 1973, personal communication).
Mount Baker Easton Glacier Mount Baker
Eruptions Ash eruptions occurred in 1840 and 1854 and steam eruptions in 1858, 1859, and 1870 (Easterbrook and Rahm,1970). Other volcanic events before 1875 reportedly occurred in 1842, 1843, 1846, 1847, 1853,and 1860 (Folsom,1970). The 1854,1858,and 1870 eruptions were observed by Professor Davidson of San Francisco and have" a distinct aspect of credibility" (Folsom, 1970@ p. 63). Mt. Baker, as well as other Cascade Mountain volcanoes, is very likely to erupt in the near future. David Frank and Jules Friedman of the U. S. Geological Survey are currently keeping the volcano under surveillance by monitoring thermal conditions of the Kiser steam field on the northeast flank of the volcano (Frank, 1973, personal communication). Mount Baker Fumarole
Geologist are sampling gases in the Crater of Mount Baker. Crater The modern summit crater probably formed about 8000 years ago and has subsequently ejected only small amounts of pyroclastic material (Jack Hyde, 1973, personal communication). Ground-based thermographs transmit air, ground, and vapor temperatures to the ERTS-1 satellite. Infrared imagery is also being used to study geothermal anomalies. Another potential indicator of activity changes is the cave system melted from the ice filling the summit crater. The size, location, and other details of caves formed in volcanic environments like that at Mount Baker reflect fumarole location, quantity of heat released, and movements of the resulting warm air masses. Thus, the study and continued observation of these caverns furnishes a sensitive means of detecting changes in geothermal activity and possibly predicting impending eruptions. Sulphur
Photo By Charles H. Anderson Jr. Caves developed in firn ice filling volcanic craters have only been reported from only two other areas in the World: mount Rainier, Washington (Kiver and Mumma, 1971; Kiver and Steele, 1971 and 1974, Mount Wrangell, Alaska (Bingham, 1967). Similar cave systems most likely exist in Iceland, the Andes Mountains, and other volcanic areas but are unreported to my knowledge. The essential components for the formation of geothermal ablation caves are. And unusually high geothermal heat source and the presence of thick snow or ice cover. Fumaroles and areas of high heat flow melt the overlying snow or ice and form cavities. A series of closely spaced "hotspots" or the upward movement: of warm air enlarges the initial cavities, into sometimes sizable passage ways. Individual chambers are, as much as 55 meters long and one continuous passage extends for nearly one kilometer in one of the two summit craters at Nount Rainier (Kiver and Mumma, 1971; Kiver and Steele, 1974). Mount Baker's unexplored caveslare probably not as extensive because its crater is smaller and fewer cave entrances exist around its perimeter. The snout of an active glacier occupies the east side of the crater and restricts firn cave formation in that area. Time did not allow our party to enter and explore Mount Baker's caverns. A more extended expedition is contemplated for the summer of 2001 when a summit area base camp will permit a more leisurely and detailed examination of the volcanic and speleologic features. DESCRIPTION OF CRATER AREA The crater of Mount Baker lies about 650 m south and 360 meters below the 3590 meter (10,7781) high summit. It is about 400 m long and 200 m wide. A low, saddle or gap on the south edge, of the crater rim furnishes easy access to those climbing the relatively easy route up tile Easton Glacier. The crater floor slopes to the cast where a narrow canyon breaches the crater rim and affords an impressive view of Mount Shuksan. The breach, leads to an ice-filled cirque feeding the Boulder Glacier. Part of the Boulder Glacier to the north near Grant Peak (elev. 10'.778') spills down the north.wall.of the crater and descends part way into the crater. Mount Baker Crater Vertical airview showing cave entrances and important geographic features. Air photo base is enlarged from U. S. Forest Service photo EXQ-6-148. A, summit crater; B, Sherman Peak (elev. 10,1001); C, south gap; D, Easton Glacier; E, Deming Glacier 8F
Photo By Jack Hyde,USGS A large snow drift extends from a gap in the west edge of the crater rim and divides the crater floor into a high snow shelf on the south side and a lower snow-covered area to the north. The most prominent cave openings are a large vertical shaft in the high Ice shelf, a large opening about 100 m to the northwest along the crater perimeter, and a very large opening near the east gap shown best. In addition, at least three smaller cave entrances are found around the perimeter of the crater at the contact of the crater wall rock and the ice fill. No cave entrances occur on the northeast side where the Boulder Glacier flows into the summit crater. Steam Cave in Mount Baker Crater A view inside slope of the west edge of Of the crater showing fumaroles and Depressions in the ice surface above firn Caves entrances.
Photo By Dr. Engene Kiver The vertical shaft in the ice shelf is estimated to be 13 meters in diameter and 10 meters deeper than the 36 meter climbing rope we lowered into the shaft. The opening is maintained by the melting effects of the steam emitted by the fumarole at its base. Steam emissions vary from small puffs to occasional larger steam eruptions that produce roaring sounds and billowing steam plumes. Whether these steam eruptions are common or occur at regular intervals could not be determined in our short visit to the crater. The 1969 photo of a similar steam eruption shown in a recent book (Easterbrook and Rahm, 1970, p. 23) suggests that steam events of small magnitude may be common. The smell of sulphur, probably H2S, is strong but not overwhelming at the crater surface. In the confines of the cave passages for extended periods the sulphur fumes could be hazardous, and might require special breathing apparatus. The vertical shaft affords an excellent view of the snow stratigraphy in this part of the crater. Six annual accumulation layers are visible. The unusually thick (6 m) annual layers occur as a result of the heavy drifting of snow downwind of the gap in the west edge of the crater and the rapid subsidence of the ice surface due to melting in the caves below. Assuming that the rate of melting and subsidence are in equilibrium, then the ice roof in the cave must be melting at a rate of six meters/year near the fumarole. This is an extremely high rate compared to the 2.0 to 3.0 m/year measured at Mount Rainier (Kiver and Steele, 1974). Ice walls close to the fumarole tend to be smooth as in the steam cups (Kiver and mumma, 1971, p. 322) found at found at Mount Rainier. Overhanging and protected walls develop the fluted pattern so common in firn and glacier caves. Fumarole gases and warm rocks on the crater floor probably melt large quantities of ice. The water drains down the crater walls presumably through deeper cave passages towards the lower part of the crater on the east side. A 300 m long continuous cave passage probably connects the large entrances on the extreme western and eastern edges of the crater. The cave passage is probably all or mostly in firn ice (specific gravity .4 to .85) although some true glacier caves (specific gravity .85+) may occur if the passages intersect the snout of the glacier that occupies part of the crater. Snow cover prevents delineation of the ice margin from the crater surface. The large cave opening on the eastern edge of the crater was not visited but was observed from the top of the ice shelf just east of the vertical ice shaft described previously. The opening is an estimated 25 meters wide and appears to furnish easy access to the cave system. Large steam plumes were observed and a loud roaring noise was heard for at least a ten-minute interval from both the eastern and western cave openings during our short visit. Only small puffs of steam were emitted from the fumaroles during the remainder of our stay. David Frank (1973, personal communication) reports that the "fumaroles and boiling pools in the east breach are impressive, needless to say." RECOMMENDATIONS FOR FUTURE INVESTIGATIONS The crater area of Mount Baker has many interesting phenomena that deserve a thorough investigation. The potential for a cave passage approximately 300 meters long between the two major fumaroles seems promising. Additional openings observed around the crater edge are cave entrances and/or crevasses caused by subsidence of the ice mass filling the crater. Ice melted in the underlying cave system is replaced by movement of ice from above into the enlarged system. Similar subsidence crevasses are associated with the summit caves at Mount Rainier. The total length of the cave system including the main passage and side passages could be as much is one kilometer at Mount Baker. The fumaroles system is an intricate part of the geologic and speleologic environment and should be studied in some detail. The number and locations of fumaroles in the surface and subsurface should be noted and preferably placed on appropriate cave and surface maps. The temperature and temperature variations should also be noted along with the type of eruptive patterns displayed by each of the larger fumaroles. Such basic descriptions would allow future comparisons to be made with present conditions and detection of major changes in behavior of tile thermal features. The cave atmosphere is strongly charged with sulphur gases. This could be hazardous or fatal if the sulphur content is too high. According to an official of the US. Army (Colonel Darrell Irvin, 1974, personal communication), a conventional military-type charcoal-filter gas mask should furnish adequate protection against sulphur gases as long as oxygen occurs in sufficient quantity in the cave passages. A mine safety lamp should be carried into unexplored passages in case pockets of air deficient in oxygen are encountered. A carbide lamp flame apparently falters after its human operator in cases where oxygen deficiency exists and should not be relied upon. A detailed study of the cave environment should also involve an analysis of the gas composition. A complete analysis requires considerable equipment and time. However, sulphur analyses can be performed using certain types of relatively inexpensive air analysis equipment currently available from Mine Safety Appliances or Edmund Scientific Company. One of the primary goals of future research should be mapping the cave passages and their associated volcanic and georiorphic features. A plane table base map or a large-scale vertical air photo of the summit crater would allow cave features and other geologically interesting features to be located accurately. The resulting maps will also provide an accurate record of present volcanic and speleologic conditions that can be used to recognize future changes of activity in the dormant volcano.The end
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