Answer Happy

Activity 6.4 Sediment from Source to Sink Name Course/Section Learning GOAL You will investigate sediment formation in Yosemite Valley, California, and consider the evolution in in shape, and composition as the sediment moves down the Merced River Date: A Look at Fig. A&.4.1. A rockfall from one of the stoep granitic walls of Yosemine Valley (A) caned boulders as large as 2 meters in diameter to crash down into the forested slope below (B) Eventally, these sediments might end up in the steep channel of a local stream (C) on their way to the Merced River (D, which flows through the main part of Yourite Valley -200m 172 Figure 4.1 1. Rockfall deposit close to the source area (Photo) (a) List all of the grain sizes that you see or that are likely to be present in the rockfall deposit shown in prefer Fig. 621 The largest selliment grain in is approximately 2 m long. Use the grain size class names listed in Fig. 6.15
(b) How would you describe the sorting of sedimentary grains in the rockfall depo? Use the terms in Fig 164 (c) How would you describe the shape of sedimentary grains you Fig. 6.160. (d) If the sediments in the rockfall deposit were lichided together as they currently rest, without any further movement downlope, what kind of sedimentary rock would they form? in the nickfall deposit? Use the terms in 2. Tributary stream just downslope from rockfall depodt (Photo-C). (a) The large sedimentary grains that can be seen in the stream channel are generally less than-15 min dumeter Judging from the turbulence of the mountain stream, what grain sizes do you expect to be carried suspended) in the water (b) What grain sizes do you expect to be rolling, sliding, or resting on the hotion of the channel, including those that you (c) How would you describe the shape of the sedimentary grains y 3. River deposits exposed in the eroded bank of the Merced River (Photo D ta) List all of the grain sines that you see or that are likely to be present in the Merced River bank shown in photo B (b) How would you describe the sorting of sedimentary grains in the streams bunk? (e) How would you describe the shape of sedimentary grains you near this stream channel (Fig. 6.168) see in the stream bank? 173
(d) If the sediments in the stream bank were lithified, what kind of sedimentary rock would they form? (e) How would you describe the change or evolution of sediments between the tributary streams and the main Merced River? 4. Use your observations to make predictions. The Merced River flows from Yosemite Valley at an elevation of -1,200 m above sea level in central Yosemite Valley to an elevation of -250 m where the river enters Lake McClure, a reservoir in the San Joaquin Valley west of Yosemite Valley. The actual distance the river travels along its channel from Yosemite to the upper end of Lake McClure is more than 65 km. You can examine the Merced River course between latitude 37.72°N. longitude 119.63 W (central Yosemite Valley) and 37.602"N, 120.100 W (inlet to Lake McClure on the Merced River) using Google Earth. (a) What sedimentary grain sizes are likely to be deposited in Lake McClure from the crosion of Yosemite Valley? (b) What do you think will be the composition of most of the sedimentary grains deposited in Lake McClure from Yosemite Valley? REFLECT & DISCUSS Based on your work, write a brief description of how the clastic sediment from Yosemite Valley might change as it travels downstream to Lake McClure. Then describe how you could use these insights to interpret clastic rocks in general.