Most people think of volcanoes as either objects of awe and fascination or as agents of destruction. Indeed, at times they can be both. However, volcanoes also contribute to commerce and culture in a myriad of ways. The seven chapters in this section explore a few of the ways in which volcanoes enrich our lives and sometimes our pocketbooks.
Modern life is highly dependent on energy to heat buildings, cook food, and run automobiles and machinery. In many volcanic regions geothermal resources are exploited either directly for heat, or indirectly for the generation of electricity. Geothermal energy may be renewable, provided that it is withdrawn at a lower rate than the natural heating. It is also clean compared with the burning of fossil fuels. These issues and other aspects of geothermal energy are discussed in the opening chapter of this section, Exploitation of Geothermal Resources.
Volcanic ash and lava from eruptions often cover large expanses of ground and are detrimental to life, but over time these same materials weather to form soils. The resulting volcanic soils have unique physical and chemical features, which affect properties such as moisture retention. Some mountainous volcanic regions are noted for their production of coffee or wine, owing to volcanically derived soils. So, if you start your day with a cup of coffee and end it with a glass of wine, volcanoes may have been indirectly responsible. The following chapter, Volcanic Soils, details the properties, distribution and formation of such soils.
Volcanic rocks are the most plentiful rock in many areas and are often employed as a building material for structures, road beds, in some types of cinder blocks, landscaping, and walls. The altered volcanic clay, bentonite, is commonly used in diverse products from drilling mud to cosmetics. The next chapter, Volcanic Materials for Commerce and Industry, describes many products derived from volcanoes.
Hot springs and fumaroles are often found in close association with volcanoes. This combination has led to the development of many spas and resorts at volcanoes. The attractive mountainous terrain of volcanic areas are also attractive sites for hiking, camping, and climbing as well viewing the various surface manifestations of volcanic activities. These and related topics are discussed in the following chapter, Volcanoes and Tourism.
Ironically, volcanic deposits are wonderful preservers of ancient buildings and artifacts, even though at the time of eruption they were undoubtedly viewed as destructive. Much of what we know of some ancient civilations was instantly preserved by the devastating force of volcanic eruptions. Examples include the well-known Roman cities of Pompeii and Herculaneum, and the Bronze Age Akrotiri in the Aegean. Other less well known sites near Ilopango in El Salvador, Arenal in Costa Rica, Sunset Crater in Arizona, Mount Rainier in Washington, Mount St. Helens in Washington, and in the Yukon Territory, have yielded clues showing the widespread effects of eruptions on the life of early peoples. The chapter Archaeology and Volcanism explores how archaeological sleuths have harvested information about early cultures and describes the origins of geomythology.
Volcanoes have often been sketched, photographed, or painted by artists. The first known volcano artist painted a mural showing an eruption viewed from Catal Huyuk, Turkey, in 6,200 B.C. Since that time, many other artists have been impressed by the grand scale of fire, light, and energy of eruptions.
In the chapter Volcanoes in Art, Haraldur Sigurdsson discusses artist's visions of volcanic eruptions through time. This chapter has more beautiful figures than any other chapter in this section, and it presents the author's unique insights into the historic depition of volcanoes in art by artists from various cultures and artistic genres.
Volcanoes are often used as metaphors for power or unpredictability. Volcanoes are also frequently viewed as windows into the interior of the earth. These ideas show up repeatedly in popular culture, and often make their way into books, movies, cartoons, and other forms of expression. Two famous examples that began as books and were later made into films are the novel The Last Days of Pompeii by George Bulwer-Lytton (1834) and the science fiction work Journey to the Center of the Earth by Jules Verne (1864). This section of the encyclopedia, and the entire text, concludes with the chapter Volcanoes in Literature and Film. This chapter provides brief descriptions and synopses of many volcano books and movies.
Readers may be surprised by the far-reaching benefits of volcanoes outlined in this section and their broad impact on our lives. While we tend to think about volcanoes primarily while they are erupting, their products and images are found in many places in both ancient and modern life. A world without volcanoes would be a duller, less economically viable, and certainly less interesting place.
Archaeology and Volcanism
VII. Geomythology: Volcanoes in Prehistoric Oral Traditions
A. Greco-Roman Myths
Dealing with the social customs and belief systems of ancient cultures, as well as their tangible remains, archaeology encompasses the relatively new discipline of geomythology, the study of oral traditions that perpetuate memories of prehistoric geologic events, such as earthquakes, floods, and volcanic eruptions. Geomythology provides not only some of humanity's oldest surviving verbal responses to volcanic activity but also some basic terminology for describing volcanic phenomena. The term "volcano" derives from the name of Vulcano, an Aeolian island in which Vulcan, the Roman god of fire and metalcraft, was believed to have set up his blazing smithy. When busy working, Vulcan employed a giant bellows that roared and sent huge sparks rising skyward. Vulcan's earlier Greek counterpart, Hephaestus, similarly a god of fire and the forge, was said to have landed on the volcanic island of Lemnos when Zeus, king of the Olympian gods, threw him from heaven, presumably accounting for the long-lived thermal activity there.
As the tale of Vulcan's noisy workshop implies, the myths of classical Greece and Rome reflect the volcanic nature of the eastern Mediterranean. In his Theogony, an epic poem about the origin of the Greek gods, Hesiod (c. 750 B.C.) describes a cosmic battle between Zeus and his giant enemies, the Titans, that depicts the conflict as it were a violently explosive eruption, perhaps a mythic echo of the Thera paroxysm. Hesiod also narrates Zeus's defeat of another fiery opponent, the dragon Typhoeus, using similar volcanic imagery. According to the dramatist Aeschylus in his Prometheus Bound, Zeus finally imprisons Typhoeus, an embodiment of primal chaos, under the bulk of Mount Etna, Europe's largest and most active volcano. Aeschylus's etiological account thus explains Etna's outbursts as Typhoeus's struggles to escape his subterranean prison, his fiery breath melting rock to produced outpourings of lava that endanger human settlements.
B. A North American Myth: The Formation of Crater Lake, Oregon
The largest Holocene eruption in North America, that which decapitated Mount Mazama about 7500 years ago to form the caldera holding Crater Lake in the Cascade Range of southern Oregon, deposited ash over a half million square miles and, without a doubt, had an impact on the lives of countless prehistoric Native Americans. Although researchers have not yet been able to correlate the physical effects of Mazama's eruption on the flora and fauna of eastern Oregon, native survivors of the volcanic holocaust apparently were so deeply impressed by it that they created an exceptionally long-lived oral tradition about the event. However improbable it seems, oral accounts of the eruption must have been transmitted through approximately 250 generations!
In 1865, Lalek, an aged member of the Klamath tribe, told William M. Colvig, then a young soldier stationed at Fort Klamath, Oregon, the story of a battle between Llao, an underworld deity who inhabited Mount Mazama, and Skell, a sky god who dwelt atop Mount Shasta, 125 miles to the south. Although it ascribes volcanic phenomena to the tempestuous rivalry between two supernatural figures, Lalek's tale includes geologic facts then unknown to white settlers, including the extreme devastation wrought by Llao's flaming mountain and its subsequent collapse to create the basin now occupied by a lake almost 2000 feet deep. The fact that Mazama once towered high above neighboring peaks and that its former summit subsided rather than blew apart was not generally recognized by geologists for many decades after Lalek's time.
C. The "Bridge of the Gods" and Cascade Volcanism
About 200 miles north of Crater Lake, native tribes living along the Columbia River Gorge of the Pacific Northwest transmitted to early missionaries other ancient myths involving seismic and volcanic events. Perhaps the best known of these concerns the "Bridge of the Gods," a natural formation that reputedly once spanned the Columbia River near the present site of Cascade Locks, Oregon. Although it is probably now impossible to disentangle later embellishment and Caucasian interpretation from the original tradition, a Klickitat account reflects some of the region's actual geologic history. According to Klickitat storytellers, long before white people appeared on the scene, native tribes were able to cross the Columbia via a land "bridge" that was tomanowos, a creation sacred to the gods. But when the tribes became greedy and quarrelsome, Tyee Sahale (commonly translated the Great Spirit) took steps that eventually led to the bridge's destruction. First, he caused all the fires in their lodges to go out. Only the fire maintained by Loowit, an aged lady who avoided the violence that divided her people, remained burning, so that all her neighbors had to come to her to reignite their campfires. When Tyee Sahale asked Loowit to name a reward for her generosity, she instantly demanded youth and beauty. Transformed into a lovely young woman, Loowit inadvertently rekindled the fires of war, attracting two intensively competitive brothers, Pahto, who ruled over territory north of the Columbia, and Wyeast, who led the Willamette people south of the river.
When Pahto and Wyeast contended furiously for Loowit's favor, hurling red-hot boulders at each other, Tyee Sahale separated them by destroying the tomanowas bridge linking their two territories, its fragments creating the cataracts for which the neighboring Cascade Range was later named. The Great Spirit also changed the three principals of this love triangle into volcanic mountains: Pahto became the broad-shouldered giant that white settlers called Mount Adams; Wyeast became Mount Hood; and Loowit, Mount St. Helens. Although St. Helens's two alpine suitors repeatedly thundered their passion, the temperamental St. Helens (whom some tribes named Tahonelatclah, fire-mountain) remained active longest, her 1980 outburst continuing the lovers' saga into the late 20th century.
An etiological myth explaining the eruptive behavior of three sentinel peaks guarding the lower Columbia, the Bridge of the Gods tradition also evokes memories of an enormous avalanche (the Bonneville Landslide) that completely dammed the river between about A.D. 1100 and 1250, forming a causeway that allowed the Indians to cross the river dry-shod. (Because the local tribes had no word for "bridge," the notion that this formation was a soaring natural arch is a Caucasian invention.) It is possible that some of the large basaltic blocks forming the landslide dam remained in place long after the river cut a new channel through its southern toe. If so, the famed Bridge of the Gods was in fact a chaotic pile of lava slabs (a native leader described the formation to a French missionary as "a long range of towering and projecting rocks") before it collapsed, possibly in the Cascade Subduction Zone earthquake of January of A.D. 1700.
Calderas • Debris Avalanches • Plate Tectonics and Volcanism • Pyroclast Transport and Deposition • Volatiles in Magmas • Volcanic Soils
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composite volcano Relatively large, long-lived constructional volcanic edifice, comprising lava and volcaniclastic products erupted from one or more vents, and their recycled equivalents.
compound volcano Volcanic massif formed from coalesced products of multiple, closely spaced, vents.
debris avalanche Catastrophic landsliding of gravitationally unstable volcano flanks resulting in a widely dispersed deposit at the foot of the edifice, typically characterized by a hummocky surface.
edifice Constructional volcanic mass.
planezes Triangular, flat-faced, facets on volcano flanks formed by the intersection of two master gullies in the upper reaches of a cone.
ring plain Region surrounding a volcano beyond lower topographic flanks, over which tephra and mass-wasting products are radially distributed.
satellite (or flank, or parasitic) vents Small monogenetic volcanic features (domes, cinder cones) distributed over the flanks of a larger composite edifice.
steady-state or equilibrium profile Shape of the edifice (cone) once an active volcano has become well established—follows the initial cone building, precedes long-term erosional degradation, and represents a balance between construction through mass addition (eruption) and degradation through erosion.
topographic inversion Process whereby through time valleys become ridges and vice versa—can occur on volcanoes as volcanogenic products such as lavas are channeled down valleys, focusing subsequent erosion along their edges.
vent Surface opening at which volcanogenic material is erupted.
Encyclopedia of Volcanoes