EXERCISE 48 PROBLEMS–PART I The following questions are based on Map T-13, the “Mono Craters, California” quadrangle (scale 1:62,500; contour interval 80 feet), and Figures 48-5 and 48-7, a detailed map and stereogram, and Map T-23a, a satellite image, of the same region. The heavily glaciated eastern crest of the Sierra Nevada is seen along the western sides of the map and stereograms (37°52'37"N, 119°12'40"W). During the Pleistocene, glaciers in this region flowed down the valleys on the eastern slope of the Sierra toward the Mono Lake basin to the northeast. Large lateral moraines are found at the mouths of each canyon. 1. (a) A small glacier is located just north of the Dana Plateau (in the northwest section of the map). In what kind of glacial landform is this glacier found? (b) What evidence suggests this feature was eroded by a glacier that was larger than the present one? 2. (a) What is the name for the kind of glacial landform illustrated by Mt. Gibbs? (On the topographic map, the dashed black line showing the boundary between Mono and Tuolumne Counties runs through the summit of Mt. Gibbs.) (b) How does this kind of glacial landform develop? Large lateral moraines can be see at the mouth of Bloody Canyon (Walker Lake and Walker Creek are between these moraines; 37°52'28"N, 119°09'53"W). The glacier that left these moraines flowed down Bloody Canyon from near Mono Pass. Sawmill Canyon (just south of Bloody Canyon) consists of two large lateral moraines—these moraines were left by a glacier that at one time also flowed down Bloody Canyon. 3. How deep (thick) was the ice in the glacier that formed the lateral moraines at the bottom of Bloody Canyon? You may assume that the ice reached the top of the lateral moraines. Estimate the height of the lateral moraine just south of the word “Lake” in “Walker Lake.” feet 4. Based on the evidence you see in the map and in the stereogram, explain the formation of Walker Lake. 5. (a) Which set of moraines formed first: the Bloody Canyon moraines or the Sawmill Canyon moraines? (b) How do you know? 0 2 = 3 4 MILES 3000 0 3000 6000 9000 12000 15000 11 18000 21000 FEET T-13 2 3 4 5 KILOMETERS La Vining Contour interval 80 ft. 400 16 Tee Vixing. Vinger PE Allery Lab ON 7354 Creek Lower Horse Meadow Here Dana Williams Butte Plateau Glacier Canon Canyon MONO 00 Springe Dana oras Gibbs 34 Mt Dana GIM Le . Creek Canyon Sidur Lake MEDARIO Y 61 Bohler Funk Ehane Canyon Wale Con Mt Gibbs mu Walker inte ta Bloody Creek Le Sardin La W prstine Lake Mono Pass Lab Mt Lewis Parker S le Parker Pass z Parker Jake Poker Lake ها را با دارا دااا Flele Lao LOCATION Mono Craters, CA 1:62,500 Crest CALIFORNIA 2 > Parker Pk Kolp PK Kuna Mt Wood Reversed Physical Geography Laboratory Manual Figure 48-7: Stereogram of Bloody Canyon and Walker Lake along the eastern crest of the Sierra Nevada. North is to the left side of the page scale 1:40,000: USGS photographs, 1993; ---N). 336 UUUUUUUUUUUUU 0 0 0 T-23a USGS Landsat 7 image of Mono Lake and the Mono Craters volcanoes, California (1999) 1:140,000 N Walker Lake Walker CA 11600 BO T1200 11000 da Bottom of Valley 1080p 00 9200 9000 Direction of Ice Flow Fifth Step 9000 Fourth Step Sardine Lake Mono Third -a Pass Summit Step 10801Upper Sardine Lake Lake Second Step First Top of Step Valley Figure 48-5: A series of glacial steps is found in Bloody Canyon, California. On this topographic map, each step is shown with abrupt change in slope (where the contour lines are close together). USGS "Koip Peak, California," US Topo quadrangle (scale approx. 1:30,000; contour interval 40 feet; N).