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Show ine dalt Lake imiyune Lake Bonneville Fell Several Times in Past ure happened sometime during and the launching of icebergs these periods @ About 21,000year: 00 to 19,000 years 000 to 17,500 years ago 500 to 16,000 years ago 000to 14.000 years ago 9.500 to 10.000 years ago The second- and third-oldest lake-level drops were discovered tt KansasState University. Oviatt studied cylindrical core samples drilled from ancient Probably not. Oviatt said other have shown NorthAtl agi “In each ofthesix instances, the er fell 100 to 160 feet. And each lake-lowering episode came a and air temperatu getting colder, not w the icebergs broke away He said other theories are the icebergs and lake ch beaches cut by falling lake wate: studying sediments the melting icebergs dropped ontheseafloor. covering northern land identified two previousiy un- known drops. Lake Bonneville about 28.000 years ago probably was the same Theyleft rock fragments scat- tered across the North Atlantic from Canadaall the way to England.’ Oviatt said He said the last Ice Age hap. pened roughly from 100,000 ‘binge and purge theory Tom Johnsonofthe Large La! Minnesota at Dulu' Thetheory says as ice sheets mas: got thicker, the bottomicelay absorbed more heat from the Earth andwere squeezed, making icebergs break offthe edges. Iey ocean-surface water slowed the transfer of heat from the to the atmosphere, in turn chang- size as the modern Great Salt years ago to 13,000 or 14,000 said. The result could have been phone from Manhattan, Kan years ago, when 1- or 2-mile-thick continental ice sheets covered most of Canadaandthe northernScientists suspect water levels in Bonneville and other large Great Basin lakes were controlled by the position ofthe jet stream. Under this theory, the lakes filled when mile-thick continental ice sheets north of Utah diverted the jet stream southward ducing Lake Bonneville water sending frequent stormsover the lake-leyel chai happened in only a few decades even though we normally think of climate changeas a very slow process Lake Bonneville basin. Could warming of Earth's cli- It indicates there can be abrupt jumps in climate change Lake, Oviatt said Tuesday by Then the lake grew larger — punctuated by four temporary drops in water level — until it reachedits largest size. the Bon neville-shoreline stage 15,000 years ago. The lake was 900 feet deeper and coveredan areaeight times larger than the Great Salt Lake. Western Utah including sites of thestate’s largest cities — was inundated The natural dam near Red Rock Pass, Idaho, failed 14,500 years ago. Within a year, water levels fell 300 feet to what is known as most UnitedStates Ks again over North America, leav ing the Great Basindrier and re levels. Johnson praised Oviatt's study as “very good He said the icebergflotillas and nals's Newsae iner MX600 Everyday Low Price 34198 Men's Reebok $39!99 Swagger Evrenee Low Price $49.99 EL February 22 & 23, 1997 Saturday & Sunday 10AM to 6PM Golden Spike Arena Events Center‘ city iG eedste) ES A eeee eg + Free Panning Lessons & Seminars * Gold Prospecting & Treasure Hunting Equipment Largest Collection of Raw Gold on Sale 566-8684 J ing jet-stream patterns, Joh thejet streamshifting northward BPNg the Provo shoreline. The water later dropped again, rose briefly to the so-called Gilbert shoreline. then fell to modernlevels. = H. i his trial v ene ili Another hypothesis is t Observatory at the Universit of the “iceberg-rafting events” by vf tuations in energy emitted by the North America. Other scientists previously determined the dates shorelines. Using fossil, chemical and geological clues inthe sedi ments, he refined the dates for known drops in lake level and ( timate impacts stability denly the conditions under which crops aregro’ vested fromthe cally impacted. it can ere cult times sun. or by ocean-circulation s that altered precipitation over continental ice sheets. soon after countless icebergs broke off the eastern edge of and sediments exposedonancient Johnson said as Dad: I Killed My Kids somehowwere triggered by fiw of the the Great § Lake Bonneville sediments west 1yg4 i fursc that are ofgreat mateexplain reduced @ Continued from A-1 heads the geology department at UAT INALLUIN, drops unrelated to the dam fail AnywhereIn The World! 1800°s Costume Contests Outdoor Equipment & Metal Detectors “aye _ eciinn ass Act will Waive up to $100 of your Door Prizes! arand Prize: “The Gold Bug” Metal Detector from Fisher Research Laboratories, Inc. LOIN|IN THEFUN S ¢ TRIKEIT RICH!” un We're in your neighborhood. 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