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Soufriere Hills, a volcano on the island of Montserrat, has provided information for those who want to study the sites of volcanic eruptions. Since 1995 this volcano on Montserrat has generated problems for the residents of this Caribbean island. On the other hand, Volcanologists take this opportunity to watch the activities of an active volcano. To begin with, Soufriere Hills is a stratovolcano. (1) Since this volcano has not erupted during recorded time, the current activity is literally forming on entirely new geological entity. The island of Montserrat sits in the Caribbean on the northern end of the Lesser Antilles. It is east of Puerto Rico and sits on the edges of the South American, Atlantic and North American Plates. (2) The cause of the volcano comes from the fact that Montserrat lies over a, Subduction zone where the North and South American plate push beneath the Caribbean Plate and form the islands of the Lesser Antilles (3). Thus, three different tectonic plates meet on the ocean floor to form these islands. The edges of these plates cause subduction zones. It is here in the subduction zone that the rocks melt into magma. (4) Since the tectonic plates are always moving in this area, and, The North and South American Plates are denser than the Caribbean Plates [they] dive under it (5). These particular subductions zone may be fifty million years old and probably lead to the islands first volcanic eruption around one hundred thousand years ago. (6) Three old craters or centers of this volcano exist. Additionally, the new eruption has created an ash delta whose survival in the seawater is uncertain. (7) The North American Plate, South American Plate, and the Caribbean Plate all lie under the Caribbean Sea. The combined motion of these plates has continued to form the islands the Lesser Antilles. The subduction zone formed at the intersection of these plates may be millions of years old. The type of geological formations of the Soufriere Hills volcano has given observers interesting material to work with. Montserrat is middle Holocene. Macgregor believes that, These tuffs are believed to have been upraised and tilted by volcanic upheaval almost contemporaneous with their formation. It seems probable that explosions more or less contemporaneous with the consolidation of the dacite [outcropping south west of landing bay], which I regard as intrusive, caused the uptilting and breaking up of the pale tuffs of Roche Bluff, not very long after their formation (8). These uplifted and broken beds probably come from the Pleistocene era. (9). Most of the geologists who have examined Montserrat and its volcano appear to agree that complicated upthrust activity has formed the island and the volcano. The area around Roach Bluff Point, Swenny s Well, and Landing Bay are composed of . . . uptilted series of yellow white tuffaceous and agglomeratic limestones (10). This constant appearance of uplift activity reinforces the idea of the movement of the tectonic plates on the sea floor and volcanic activity, all of which contributed to the formation of the island of Montserrat. Additionally, several extinct features are on the island. On the north half of the island are the Centre Hills, and the Harris-Bugby Ridge. (11) In the south part of the island are lava flow deposits and the various craters around Soufriere Hills. The south part of the island contains Soufriere Hills and South Soufriere Hills, and several rivers and streams flow through this area. The Tar, the White and Paradise are bodies of flowing water on the south part of Montserrat. Saint George s Hill, 1185 feet, appears approximately half way from the southern tip to the center, not far south of a flowing body of water named Belham. On the mountainous north part of the island the Big B Collins are the two moving bodies of water. Silver Hill is the northern most peak and is 1,323 feet in elevation. Lava flow deposits are in the southeast part of the island. Lava flow deposits have created Fort Ghaut, Gingoes Ghaut, and White Ghaut (12). These Gharts represent, Widespread unconsolidated pyroclastic flow deposits, mainly of andesitic composition, are exposed in ghauts north east and south west of the volcano (13). These ghauts obviously provide evidence of the activities of the volcano and they give scientist away to study the growth and mineral composition of the volcano.
A variety of rock and minerals exist on Montserrat. Many of the volcanic flow deposits near the volcano are of andesitic composition (14). Some of the lava flows include pyroclastic White River fall, which has a basaltic composition (15). On the whole, the main type of rock on Montserrat is limestone, dark-spotted, yellow, fine-grained limestone with fragments of calcareous algae; Amphistegina, Archaias, Globigerina. Some magnetites (16). Fine-grained yellow limestone also appears with the mineral content of the following, Amphistegina and Globigerina. Magnetite grains are present in varying qualities (17). Macgregor refers to the limestone as coral limestone and tuffaceous limestone because of the content of algae and various sea creatures in the rock (18).Both geology and geography have an effect on the population of an area. Both aspects may determine the types of industry within a given area and even influence who settles there as well as how many people settle there. Initially, the geology of plate tectonics has created this island along with others in the Antilles. The shifting of the plates and the constraint of the subduction zone has entirely changed the lives of the inhabitants on Montserrat. Since Montserrat is an island, getting away from the volcano presents more of a challenge than if this formation were on a continent. After the volcano started erupting in 1995, Cruise ships skirted the island. A medical school moved to St. Marten. Unemployment rose from seven percent to fifty percent (19). Almost immediately the economy of this British Island collapsed. One third of the inhabitants left (20). Much of the population of this idyllic island has been moved to the northern end for safety purposes. It appears that the residents are slowly being squeezed off the island. Everyone from hotel owners to farmers has felt the difficulty of the volcanic eruption. Since there is no way to know how long these eruptions will go on, many people who have been evacuated from the end of the island have no idea what their future holds. Endnotes 1. Soufriere Hills, Montserrat, West Indies, November 12, 1998 http://volcano.und.nodak.edu/vwdocs/current_volcs/montserrat/montserrat.html2. Williams, A.R, Under the Volcano Montserrat, National Geographic, Vol. 192, No. 1, July 1997 64.3. Williams 64.4. Williams 64.5. Williams 64.6. Williams 64.7. Soufriere Hills, Montserrat, West Indies8. Westerman, J.H. Kiel, H. The Geology of Saba and St. Eustatius, With notes on the Geology of St. Kitts, Nevis and Montserrat (Lesser Antilles), Amsterdam: Natuurwetenschappelijke Studiekring Voor Surname en de Nederlandse Antillen, December 1961,1589. Westerman & Kiel 129.10. Westerman & Kiel 129.11. Case, J.E, Edited by Gabriel Dengo, The Geology of North America, Volume H, The Caribbean Region. Menlo Park, California, The Geological Society of America, 1990, 152.12. Case 152.13. Case 152.14. Case 152.15. Westerman & Kiel 129.16. Westerman & Kiel 129.17. Westerman & Kiel 129.18. Westerman & Kiel 129.19. Williams 65.20. Williams 65.