Intro- The Ice Age in Utah Hace 18,000 años en Utah La Edad de hielo en Utah Salt Lake City Lago Bonneville glaciares During the most recent Ice Age in Utah, glaciers blanketed the mountains and Lake Bonneville covered most of Utah’s western valleys. Habitats suitable for mammoths, mastodons, camels, horses, muskoxen, long-horned bison, and saber-toothed cats, were restricted to the margins of Lake Bonneville and the periphery of mountain glaciers. Climate effects during the Ice Age became drastic by the end of the Pleistocene. There was a net loss of plant and animal diversity and ultimately mastodons, mammoths, camels, horses, ground sloths, and many other species became extinct. The extinction of these Pleistocene animals is not well understood. Two main theories are the “Pleistocene Overkill Theory”, which states that large animals were killed off by early humans, and the “Climate Theory” which holds that large animals failed to adjust to rapid climate changes.

El lago Bonneville y el hielo cubriendo Utah durante el alto Pleistoceno Hace 18000 años Montañas Uinta Lake Bonneville and Ice Coverage in Utah During the Late Pleistocene ~18,000 years ago This map shows Lake Bonneville and the maximum extent of ice coverage in Utah about 18,000 years ago. Notice the broad expanse of ice that covered the Uinta Mountains! The Wasatch Range also underwent some glaciation during the most recent ice age. The power of these large glaciers hundreds of feet thick left their mark on the mountainous landscape of the Wasatch, creating most of the beautiful mountain scenery we have today. The cooler, wetter climate in the late Pleistocene caused Lake Bonneville to rise to its maximum level and large amounts of snow and ice to accumulate in mountainous regions. Cordillera Wasatch

Lago Bonneville Hace 18000 años Salt Lake Lake Bonneville ~18,000 years ago Regional map of Lake Bonneville at its highstand about 18,000 years ago. Note that Lake Bonneville extended across most of northwestern Utah and into parts of Idaho and Nevada. Delta Utah

La subida y bajada del lago Bonneville Nivel de Provo hace 17000 años El gran lago Salado actualmente El nivel de Gilbert hace 12000 años El nivel de Bonneville hace 18000 años The Rise and Fall of Lake Bonneville The hydrograph for Lake Bonneville represents lake levels over the past 24,000 years. Maps of Lake Bonneville (background) indicate when the four major shorelines were formed; Stansbury, Bonneville, Provo and Gilbert. The location of present-day Great Salt Lake is depicted in dark blue. Hidrografía del lago Bonneville Nivel del Stansbury Hace 24000 años

La orilla de Stansbury hace 24000 años Ogden Delta Nephi Provo Salt Lake UT ID NV Paso de Red Rock La orilla de Stansbury hace 24000 años Isla Stansbury Stansbury Shoreline ~ 24,000 years ago This map shows the Stansbury level of Lake Bonneville about 24,000 years ago. At this time, cooler and wetter climate conditions caused the lake to begin to rise from a level close to that of the present-day Great Salt Lake. The Stansbury shoreline, the oldest of the four major shorelines, actually formed during the transgressive phase of Lake Bonneville as the lake was rising. The Stansbury shoreline is usually difficult to see, but can be spotted (from I-80) on the south end of Stansbury Island.

Bonneville Shoreline ~18,000 years ago Paso de Red Rock UT ID NV la orilla de Shoreline Ogden Delta Nephi Provo Salt Lake Hace 18000 años Punta de la montaña Bonneville Shoreline ~18,000 years ago This map depicts Lake Bonneville about 18,000 years ago. This is the highest stage of Lake Bonneville and at this time the lake level was controlled by a threshold near Red Rock Pass, Idaho. About 17,500 years ago, the threshold broke and water spilled out catastrophically into the Snake River drainage. This event is called the Bonneville flood. It is estimated that in less than one year, the amount of water that flowed out of Lake Bonneville was equivalent to all of the freshwater flowing in the world today! One of the best places to view the Bonneville shoreline is at Point of the Mountain in Draper, Utah. The flat bench extending from Point of the Mountain to the east was formed by waves and currents in Lake Bonneville.

Provo Shoreline ~17,000 years ago Paso Red Rock UT ID NV Orilla de Provo Ogden Delta Nephi Provo Salt Lake Hace 17000 años Provo Shoreline ~17,000 years ago This map shows the Provo level of Lake Bonneville about 17,000 years ago. During the Bonneville flood, the lake dropped about 340 feet to the Provo level where it remained for approximately 2,500 years. The Provo shoreline is one of the most visible shorelines in the Bonneville basin and is commonly covered by a calcium carbonate deposit called tufa (see slide #19 for a description of tufa).

Gilbert Shoreline ~12,000 years ago Ogden Delta Nephi Provo Salt Lake UT ID NV Red Rock Pass Orilla de Gilbert Hace 12000 años Gilbert Shoreline ~12,000 years ago This map depicts the Gilbert level of Lake Bonneville about 12,000 years ago. About 14,000 years ago, the climate became warmer and drier and the lake level began to drop. Some evidence exists that the lake almost completely dried up before rising to the Gilbert level about 12,000 years ago. The Gilbert level is difficult to see because it is only about 50 feet higher than the current Great Salt Lake and is covered in many places by buildings and roads.

Gran Lago Salado actualmente Ogden Delta Nephi Provo Salt Lake UT ID NV Paso de Red Rock Gran Lago Salado actualmente Great Salt Lake Today This map depicts present-day Great Salt Lake. Great Salt Lake is the largest remaining remnant of Lake Bonneville. Other relics of Lake Bonneville are Utah Lake, Sevier Lake, and the Great Salt Lake Desert containing the famous Bonneville Salt Flats. The chemical composition of Great Salt Lake is similar to that of typical ocean water. Sodium and chloride are the major ions in the water, followed by sulfate, magnesium, calcium, and potassium.  Although much of the salt contained in the Great Salt Lake was originally in the water of Lake Bonneville, a small amount of dissolved salts is deposited in the lake every year by rivers and numerous small streams that feed into it. As the lake rises, its salinity drops because the same amount of salt is dissolved in more water. In historical time, the lake's salinity has ranged from a little less than 5% (just above that of sea water) to nearly 27% (beyond which water cannot hold more salt).

Orillas del lago Bonneville en la isla Antelope Provo Orilla sin nombre Stansbury Shorelines of Lake Bonneville on Antelope Island Well-defined shorelines are visible at Buffalo Point on the northwest side of Antelope Island. Notice that there are more than four shorelines present. Dozens of unnamed shorelines associated with the oscillations of Lake Bonneville can be seen around the Bonneville basin. Gilbert Orilla sin nombre

La orilla de Bonneville en la falda de la montaña Bonneville Shoreline at Point of the Mountain (view to the southwest) This once pristine shoreline near Draper, Utah, is now the site of subdivisions and an expanding gravel pit. The site is also a popular hang gliding and paragliding launch spot. Note the paragliders flying above the ridge on the inset to the right. With increasing building and excavation in this area, pilots are running out of places to land! Paramontañas

La orilla de Bonneville en la falda de la montaña La orilla de Bonneville en la “U” Bonneville Shoreline at the “U” and Point of the Mountain These are two good spots to view the Bonneville shoreline. At the University of Utah, the Bonneville shoreline forms the bench just under the “U” on the mountainside. This bench is the site of the popular Bonneville Shoreline Trail that is frequented by hikers and mountain bikers. The Bonneville shoreline is still somewhat intact on the south side of Point of the Mountain and can be seen looking north from I-15. La orilla de Bonneville en la falda de la montaña

Arrecife en el lago Bonneville Barrera moderna Isla Kiawah , Carolina del sur Arrecife en el lago Bonneville Lake Bonneville Barrier Bar and Spit (view to the north, from highway SR 36) The lower photo is of the Stockton Bar, located in Tooele County, Utah. The Stockton Bar is a composite of barrier bars and spits that formed in Lake Bonneville when it was near its highest level. The Stockton Bar formed much in the same way as the modern barrier bar and spit at Kiawah Island, South Carolina. A spit forms when sediment is transported along a shoreline and is deposited in a fingerlike extension into a body of water. A barrier bar is simply a spit that has extended all the way across a body of water and has become attached to the shoreline on both ends. Barrera moderna Stockton , Utah

Esculpidos en el lago Bonneville Esculpido joven Superficie de contacto Lake Bonneville Spits This picture shows a younger spit that has built out over an older spit near Fish Springs, Juab County, Utah. Note the different angles at which the sediments were deposited. The older spit is made up of horizontal (flat lying) layers that indicate that lake level was rising about as fast as sediment was being deposited. The steeply dipping beds of the younger spit indicate that sediment was accumulating faster than the lake was rising during this time. Esculpido antiguo

Lago Bonneville sedimentos del fondo marino Laminas Lake Bonneville Deep-Water Sediments Most sediments in deep water are very fine-grained silt and clay and settle very slowly to the lake bottom. Many of these deposits are finely layered (laminated), indicating a change in lake chemistry or sediment input.

Toba volcánica en la orilla de Provo Tufa on the Provo Shoreline This is a view of tufa on the Provo shoreline near Delta, Utah. Tufa is a hard coating made of calcium carbonate that covers rocks and sediments. It formed when the concentration of dissolved solids in the lake increased due to a decrease in lake level. Tufa is easy to spot because it looks like a pile of concrete that has been dumped out of a cement truck! Toba de cuarcita

Delta del lago Bonneville Dirección del transporte de sedimentos Lake Bonneville Delta at Rock Creek, Utah County (view to the northwest) Deltas form when sediments carried by rivers and streams are deposited into a standing body of water (lake or ocean). Rock Creek delta was formed in Lake Bonneville as sediments were transported down American Fork Canyon and dumped into the lake. The layers of sand and gravel are dipping toward the center of the valley (to the west), where the deepest part of the lake was located.

La linea de la orilla de Provo plataforma cortada por el viento Provo Shoreline Wave-Cut Platform This wave-cut platform is located on the Provo shoreline near Lucin, Utah. The platform (a bedrock terrace left behind by the receding cliff) was formed by strong currents and waves eroding away the hard rock that forms the cliff in the center of the photo. Dirección del viento

Linea de la orilla de Provo Salinas de Bonneville Orilla de Bonneville Linea de la orilla de Provo Bonneville Salt Flats The Bonneville Salt Flats can be seen from I-80 near Wendover, Utah. When Lake Bonneville evaporated, salt from the water was left behind on the dry lake bed. The Bonneville Salt Flats are one of the flattest areas on earth and are the site of many land-speed records set by race cars. In the background, the Bonneville and Provo shorelines can be seen on the Silver Island Range. Sal

Modernos glaciares en Alaska Modern Glaciers - Alaska Most of the large continental ice sheets have disappeared since the Last Glacial Maximum about 18,000 years ago, but many mountain glaciers still exist around the world. These images depict two glaciers in Alaska; the Devil’s Desk Glacier that perches high on a mountainside, and the Halo Glacier that extends down to sea level. Glaciar de Devil’s Desk Glaciar Halo , Cook Inlet

Glaciar Holgate , Alaska Holgate Glacier, Kenai Peninsula, Alaska This glacier on the Kenai Peninsula is one of several glaciers from the Harding Icefield. Can you picture what the valley looks like beneath the glacier?

Montañas de Sierra Nevada Glaciar Cirques Montañas Uinta circo Glacial Cirques A cirque is formed when a glacier scours out a semi-circular basin on a mountainside. The upper photo shows a cirque in the Uinta Mountains, which were extensively glaciated during the last glacial episode (~ 18,000 years ago). Convict Lake occupies another late Pleistocene glacial cirque that formed in the Sierra Nevada Mountains. Circo Lago Convict , Montañas de Sierra Nevada

cañones con la forma de U glaciar Valle de Yosemite Cañon de Little Cottonwood U-shaped Glacial Valleys When a glacier moves down a valley/canyon, it erodes and scours everything in its path. After the glacier recedes, a characteristic “U-shaped” valley is left behind. Parque nacional glaciar

Cañón de Mill Creek forma de V Cañón de Little Cottonwood forma de U glaciar “U-shaped” and V-shaped” Valleys Little Cottonwood Canyon displays the characteristic U-shape of glacially carved valleys/canyons. Mill Creek Canyon, in comparison, is V-shaped, which is typical of valleys formed mainly by stream erosion. Cañón de Mill Creek forma de V

Glacial Scenery en Alta, Utah Glacial Scenery at Little Cottonwood Canyon During the last ice age (~ 18,000 years ago), glaciers advanced down Little Cottonwood Canyon to the canyon mouth. The glaciers scoured the canyon floor and walls, leaving behind a classic “U – shaped” valley that is characteristic of glacial erosion. Glacially carved canyons typically have steep, smooth walls. Arêtes are sharp, knife-edge ridges that are formed when two glaciers erode adjacent tributary canyons. Glacial Scenery en Alta, Utah

Montañas de Moraines Chugach, Alaska Morrena media Moraines, Chugach Mountains, Alaska A glacial moraine is a ridge of rock and debris that has been scoured and “bulldozed” by a glacier. Lateral moraines form on the sides of glaciers, medial moraines form when lateral moraines from two or more tributary glaciers merge, and terminal moraines form at the ends of glaciers. This unnamed glacier is just one of many glaciers that are retreating in Alaska's Chugach Mountains. The elevated medial moraine is a sign of retreat. Image by Michael Collier

Señales de glaciar en Little Cottonwood Linea del borde Morrenas Glacial Features at Little Cottonwood Canyon, Salt Lake County Several characteristic glacial features, including moraines and the U-shaped valley, can be seen at the mouth of Little Cottonwood Canyon. A trimline (here seen as a change from a smooth slope to a steeper, more rugged slope) marks the maximum upper level of the margins of a glacier. The fault scarps formed when large earthquakes occurred on this portion of the Wasatch fault. Valle en forma de U salto de falla

Sedimentos del glaciar Parque nacional de Voyageurs, Minnesota Glacial Erratics Erratics are rock fragments that have been carried by glacial ice and deposited some distance from their original source. Erratics can be as small as a pebble to as large as a house! Note the person in the lower photograph for scale. Parque nacional de Denali, Alaska Persona

Cañón de Little Cottonwood Little Cottonwood Canyon Glacial Erratics Many erratics are located near the mouth of Little Cottonwood Canyon. The erratic in the lower photo was the popular “painted rock” near the intersection of 9400 South and Wasatch Boulevard. This photo was taken in April of 2002 and the rock has since been removed to make way for a new housing development. Sedimentos

Pulidos y marcas glaciares Glaciar de bedrock, Montana Glacial Polish and Grooves Glacial ice contains a lot of rock fragments and debris that help to erode bedrock at the base and sides of a glacier. Small fragments such as sand tend to polish and smooth the surface of the bedrock. Larger pebbles can carve out parallel striations or grooves on the bedrock as they move along with the ice. Estrias

La vida en Utah durante la edad de hielo Life in Utah During the Ice Age Most of what we know about life in Utah during the Ice Age is based on fossils found in Lake Bonneville shoreline deposits. These fossils date from approximately 20,000 – 10,000 years ago, which is also the time of the latest period of glaciation at the very end of the Ice Age. Ice Age fossils are found in Utah right up until the time of the Pleistocene Extinction. New discoveries of fossil vertebrates in Utah provides us with some information about some of the many animals that lived here during the Ice Age. A nearly complete skeleton of the Colombian mammoth, Mammuthus columbi, along with plant fossils, and an associated cheekbone with teeth of the giant short-faced bear, Arctodus simus, was discovered by construction crews in Huntington Canyon, between Fairview and Huntington, Utah in 1988. Two other mammoth sites were discovered in 1995: The complete lower jaw of a baby mammoth was found along with the skeletal remains of a muskoxen at Bear Lake, Utah, and construction workers discovered the complete tusk of an adult mammoth about 7 feet long and nearly a foot in diameter near Logan, Utah. Other Ice Age fossils from Utah have been found in cave deposits of southern and western Utah; and Utah’s only early Ice Age fossils, which are about one million years old, from Little Dell Reservoir just east of Salt Lake City.

Life in Utah at the end of the Ice Age This is a scene from the Ice Age mural by Joseph S. Venus at the College of Eastern Utah Prehistoric Museum in Price, Utah. It is a reconstruction of Ice Age life found in Utah.

Moluscos en el lago Bonneville Assorted Lake Bonneville Mollusks Lake Bonneville supported various species of clams and snails. Some species still exist in small isolated populations in streams and springs. The photo above displays some of these species found in Lake Bonneville sediments. Gastropods (Snails): Stagnicola, Stuccinea, Physella, Planorbella, Valvata, Gyraulus; Bivalves (Clams & Oysters): Anodonta.

Buscando gastrópodos (caracoles) Hunting for Gastropods Here, a research group is searching for gastropod (snail) shells near the Deep Creek Mountains in western Utah. Scientists often use fossils as indicators of environmental conditions (e.g. salinity, temperature, light penetration, etc.) and for radiocarbon dating. Also shown is a close-up view of Pyragalopsis sp. and Stagnicola bonnevillensis, two common species of snails found in Lake Bonneville sediments. These snails lived in the quiet, relatively shallow waters of Lake Bonneville and fed off of algae growing on the lake-bottom sediments. .

Pájaros gigantes en la edad de hielo en Utah Teratornis Utah’s Giant Ice Age Birds The teratorns are closely related to vultures and condors, which were also found in large numbers in the Great Basin during the Ice Age. These impressive giant birds had a wingspan of roughly 16-25 feet or more and weighed 35 pounds. They had a hooked, somewhat eagle-like beak. The decline of the condors, teratorns, and vultures in western North America sometime toward the end of the last Ice Age coincides with the extinction of large mammals such as mastodons, giant sloths, camels, and saber-toothed cats that these giant birds fed on. The California condors are among the largest flying birds in the world. Adults weigh approximately 22 pounds and have a wing span up to 9½  feet. During the late Pleistocene the condor could be found in great numbers all over the southwestern United States. Currently the California condor is endangered and a recovery program is underway to re-establish the species through captive breeding. Today condors are being reintroduced into the mountains of southern California, the central California coast, and near the Grand Canyon in Arizona. Teratornis skeleton Condor de California cráneo de Teratornis

Puentes en la edad de hielo y migraciones de los mamíferos Ice Age Land Bridges and Mammal Migrations Mammoths, mastodons, and bison migrated from Eurasia to North America. Camels and horses migrated from North America to Eurasia. Camels, deer, rabbits, rodents, dogs, and cats migrated from North America to South America. Ground sloths, porcupines, and armadillos migrated from South America to North America.

Elefantes de la edad de hielo Ice Age Elephants - Mammoths and Mastodons Mammoths (Mammuthus) and mastodons (Mammut), members of the order Proboscidea, are extinct relatives of living elephants that were common throughout the Ice Age of North America. The mastodons evolved in Africa about 35 million years ago and spread throughout Africa, Europe, and Asia. About 3.7 million years ago mastodons migrated to North America via the Bering Land Bridge. The mammoths appeared in sub-Sahara Africa about 3-4 million years ago, migrated across Europe, Asia, and Berengia, and eventually crossed over the Bering Land Bridge into North America about 1.7 million years ago. Both the mastodon and mammoth became extinct at the end of the Ice Age, about 10,000 years ago. Mamut Mastodonte El mamut de Huntington (

Saber-toothed Cat The saber-toothed cat (Smilodon) from the Late Pleistocene was the size of a lion and had enlarged canines that looked like small elephant tusks. Unlike lions, which have long tails that help provide balance when the animals run, Smilodons had bobtails which suggests that they probably did not chase down prey, but charged from ambush instead, waiting for prey to come close before attacking. The saber-toothed cat went extinct about 10,000 years ago. A few bones of the species Smilodon californicus have been found near Park City. Smilodon fatalis

Perezoso gigante Giant Ground Sloth The extinct giant ground sloths of North America, relatives of the modern South American tree sloths, migrated from South America during the late Pleistocene. Two species of ground sloth lived in Utah during the Ice Age. Jefferson’s ground sloth (Megalonyx jeffersoni), named after the third President of the United States, Thomas Jefferson, was the size of a bison. Harlan’s ground sloth (Glossotherium harlani) was larger than the Jefferson’s ground sloth and had small pebble-like bones under its skin, which may have served as armor against predators.