The geography 491 class of fall 2013.
Dana Meadow was one of the many stops on Day 5 where Phil Larson taught us about the formation of the Sierra Mountains. We had made multiple stops earlier learning about the physical landscape of Yosemite National Park. The meadow has a meandering stream and unsorted soil deposits. We learned that this site was an example of a classic glacial deposit and we noted the changes of the environment as moved from stop to stop.
Pictured: The meandering stream that dissects Dana Meadow.
Pictured: Aaron takes a leap off of a rock that was dropped in the meadow by a glacier while the class takes notes and makes observations.
Erik Westerlund and his wife Lee invited us into their home at the end of Day 6. Erik explained to us that their house was made out of straw or hay blocks in order to keep the house warm in the winter and cool in the summer, which was very important for living in the drier desert like type of environment. It is just one feature about the house that is energy efficient, use of solar panels, and a homegrown garden helps the family live more “green” being a local park ranger it is important that they do so. We also enjoy learning to make “rockamole” Erik Westerlund’s guacamole recipe that has been perfected! As the sun set we all gathered round and listened to Alex’s presentation on John Muir the naturalist that left a huge impression on the park. It gave us all time to reflect on and share some of the amazing places, people, and opportunities that we experienced so far while being in the park.
Pictured: A sunset from the Westerlund's porch.
Facelift is a program that has been going on for ten years. It is lead by climbers and park rangers in effort to clean up Yosemite after the all the visitors and climbers have long left the park. Over the past ten years the park has collected over a million pounds of garbage that has been left behind. These efforts are not only important in keeping the park clean, but to also preserve it for future generations and their use of the park.
Pictured: Half the class posed for a picture while volunteering to clean up the park as part of the Facelift program.
The fire lookout was the last stop that we made in the Yosemite National Park. From there we could see the extent of the damage made by the rim fire. The lookout is one of the locations where firefighters make plans to tackle the large fires like the one that spread so quickly throughout the valley. Ryan and Brittany gave their presentations on the golden trout, the state fish of California and Hetch Hetchy reservoir. It was interesting to be able to see where the firefighters of Yosemite Valley make plans to tame the rim fire. It was shocking to see scorched rock and numerous blackened and burnt down trees after spending our week in an untouched area of the park.
Pictured: Jenna points out the boundary of the rim fire on a map that was posted outside the fire lookout.
Pictured: This image shows the blackened trees that were left standing and just how much damage the fire caused in the area surrounding the fire lookout.
Pictured: Here are some documents that can be found in the lookout tower.
Pictured: Ryan gives us one of the final presentations of the trip on the golden trout, the state fish of California.
Before heading into the valley we stopped at In-N-Out Burger. Most of us had never had In-N- Out before so we had to stop and try a local favorite. Dinner consisted of delicious cheeseburgers and chocolate shakes.
Jenna Beers was our guide from NatureBridge, the program our class went through for accommodations in Curry Village as well as our visit to the cabin in Merced Grove. We got all our meals through this organization, both in the village and packed lunches. Jenna came with to all of our tours in the park, guided the hike to North Dome, and taught us many things about Yosemite and camping in general, including informative advice on how to relieve ourselves in nature.
Pictured: Jenna cooks our dinner at the Merced Cabin.
Our group’s accommodations were located in Curry Village, the largest housing facility for park visitors. They offer many different kinds of lodging including motel rooms, cabins, and canvas top tents. We stayed in the tents, ate breakfast and dinner in their cafeteria, and explored the surrounding beauty of the park.
Pictured: (left to right) Phil Larson, Blake Westerlund, Harry Jol and Erik Westerlund in front of a tent in Curry Village.
We visited this area of the park on day 5 of our trip. Our group walked through the meadow and climbed the dome where we learned about how both of these landforms were formed, and ate our bag lunches. Pothole Dome is said have been created by fluvial processes, carved by rivers, ice, or deep-seated weathering which created a “stepped” landscape. Many of mountains surrounding the valley are the only ones in the park that are still volcanic, which is made evident by their reddish hue. The meadow itself is one of the largest high-elevation meadows in the Sierra Nevada.
Pictured: Pothole Dome.
Pictured: Tuolumne Meadow.
Pictured: Part of our class standing on the dome and learning about the landscape.
Learning about the native people that first inhabited Yosemite Valley, the Miwok Indian tribe, is an important part of this National Park’s history. These people had a rich culture and they lived off the land as many as 10,000 years ago. The Miwoks frequently traded with other Native Americans in the region and made a fine life for themselves until the 1850’s when newcomers flocked to California in search of gold, tragically forcing these people out of their homes. However, Julia Parker, a descendent of the Miwoks and current resident of the valley, leads tours and educates visitors about the history and traditional practices of her ancestors.
Our group had the privilege of learning many things from Julia Parker. We were taught about the Miwok people’s creation story, means of gathering food, and their general beliefs and practices. We were taken into their sacred longhouse where many traditional ceremonies are still performed and we were able to ask Julia questions. This tour added a unique view of the valley and contributed to our group’s well-rounded perspective of Yosemite National Park.
Pictured: Julia Parker smiled as she spoke about her ancestors.
Pictured: The area of the valley that is dedicated to preserving the traditional Mioak structures.
Pictured: Part of the group with Julia Parker.
Dr. Phillip Larson is a Blugold. As an undergrad at the University of Wisconsin, Phil double majored in Geology and Geography, and often found himself conducting research with Harry Jol. After sadly leaving his proud blugold heritage behind, Phil went to grad school at Arizona State University, where he would get his masters and eventually his doctorate in physical geomorphology. You can find the man now teaching at Mankato State University back in the Midwest. Yosemite was a major focus for Phil in his research with ASU, and we were lucky enough to have him along to share his knowledge of the geomorphic history of Yosemite.
Pictured: Phil sat under the natural bridge we came across during our hike to North Dome.
Day six had a beautiful hike in store for us as we ventured to the trail heading of North Dome. The 4.4 mile hike varied greatly in terrain and elevation. When we finally reached the end of our hike, we were greeted by one of the most stunning views on the entire trip. To the left we could see Tuolumne Meadow and Half Dome and to the right we could see Cooks Meadow and El Capitan. The hike was worth it completely and truly was one of the highlights of the trip.
Pictured: a few class members hike towards the tip of North Dome.
After dropping off the eastern side of the Sierra Nevada mountain range, we encountered a very dry, desert like climate in Lee Vining. The vegetation here is very different as we saw more shrubs and other desert vegetation. Lee Vining is enclosed by lateral moraines caused by the recession of a glacier on the side walls, and a recessional moraine on the west.
Pictured: a large, fragrent sage brush meadow.
While most of our group was working on the other scientific research, three members of the class went with Jenna to learn about the plant life that resides on the El Capitan Moraine. Since there is a wide variety of different flora in this area, we focused on learning about the main types of trees that grow on the moraine.
There are three trees that are most often found in this region of the park. The California Incense Cedar is identified by its strippy bark, flat, splayed needles, and lack of cones. The Douglas Fir is the tallest of the three, reaching as many as 100-120 meters in height. The Fir is categorized by its grayish bark with furrows that deepen as it matures and its small needles with tailed cones. The last of the three is the Ponderosa Pine which is a large conifer. This tree has what is called “puzzle piece” bark which also has plates and furrows. Its needles are in fascicles and it has large cones.
In order to study the general dispersion of these types of the trees across the moraine, we walked along a one hundred meter line and documented all species found, their ages, and proximity to each other within two meters across the initial section. This is called a transaction and is a reliable way of studying the common types of plants found in a diverse area.
Pictured: Jenna gave a few of us a botany lesson on plants around the moraine.
Pictured: Rachel, Alex, and Brittany documenting plant species in the research area.
Olmstead Point displayed some of the most “glacial polishing” we encountered on our visit to Yosemite. Glacial polishing is a characteristic of a rock which has been smoothed or scarified by a glacier passing over it. Here we also discovered huge erratics which were deposited by the retreating glaciers; we could tell they were erratics because of the different consistency in feldspars.
Pictured: Aaron and Jenna standing near a large erratic on Olmstead Point.
We met up with Greg Stock in Cooks Meadow and he took us for a tour of an area heavily affected by rockfalls. He gave us the history of the valley while also discussing some of the issues he has to address as the head geologist of the park. One issue he has to deal with regularly is rockfalls. As of 15 thousand years ago, rockfalls became the primary source of geomorphology in the valley as there is approximately one rockfall per week. The abundance of rockfalls creates a need for risk assessment as there is a large number of people moving through the park each day.
Pictured: Greg tells the class about the dangers of rockfalls.
Jenna made a recommendation to stop at Mountain Sage for coffee on our way out of town. The shop is in Groveland and features some local photography and even has a plant nursery in the backyard.
Pictured: Dave is taking time in the Mountain Sage nursery to reflect on the long wonderful journey we had in Yosemite National Park.
Phil Larson explained that Tanaya lake was a valley carved by glacial movement. Trees grew in this area 1,000 years ago, before it became filled with water. You can see tips of trees that still remain in the center of this lake.
Pictured: Nick Jaeger (Left) and Blake Westerlund (right) pose for a picture in front of Tanaya Lake.
Merced Cabin, within the grove, served as our shelter for the evening. The cabin was built in the 1930’s and is without power, heated only by a woodstove. The grove itself, however, has a large population of sequoia.
Pictured: Here Nick and Will give their lesson on Sequoias in Merced grove which is where we spent our last night.
Pictured: Hiking to the Merced cabin with all of our gear.
Pictured: Merced Cabin
The ecosystem of Mono Lake consists of alkali flies, their larvae, brine shrimp and the gulls that feed on them. The native Kutzadika’a people used the fly larvae as a food source as well. Los Angeles used the water source that flowed into the lake to supply the city and it had severely lowered the level of the lake. In the lake are several mineral formations known as tufa. Tufa is highly porous and is a variety of limestone; these formations arise in ambient temperature water bodies.
The Ansel Adams Gallery is located in Yosemite Valley. There you can see or purchase some of Ansel Adams’ original prints. The gallery also offers Ansel Adams walking tours which takes you through some scenic locations in the valley. Our tour guide, Kirk, gave us the history of Ansel Adams and the park as well as some pointers on how to take successful photographs of the scenery.
Pictured: Kirk showing us some examples of Ansel Adams’ work in Cooks Meadow.
The El Capitan Moraine is located within Yosemite National Park, and lies directly west of El Capitan Meadow. It is orientated perpendicular to the valley floor in a north south fashion, with the Merced River flowing through its south end. The El Capitan Moraine is a recessional moraine, and was formed as the Tioga-age glacier paused briefly nearly 15,000 years ago in its retreat from the valley (Glazner & Stock, 2010). Subsequently as the glacier continued to retreat out of Yosemite Valley, glacial melt water began to fill in the depression left behind. Serving as a natural dam, the El Capitan Moraine forced sediment carried downstream by the Merced River to be deposited in the flood plain directly east of the moraine. Over time these sediments filled the basin in which set the current form of the valley floor that can be seen today which is noticeably higher than the valley floor west of the moraine.
The characteristics of the Merced River differ east and west of the moraine. Specifically, east of the moraine, the meandering nature of the Merced River prior to 1879 frequently flooded with seasonal runoff due to the naturally elevated local baselevel set by the moraine. In addition to creating swampy, mosquito filled ponds in the Central Chamber, flooding events also disrupted human activity in the park. To solve these issues with a quick and easy fix, an early guardian of the valley, Glen Clark, blasted the moraine where the Merced River channel intersected. This blasting of the moraine by Clark presumably succeeded in making two major changes: 1.) By blasting the boulders, the bottleneck in the moraine gap was removed allowing better drainage during seasonal flooding and thus reducing the size of the reservoir behind the dam, and 2.) by blasting the boulders, the base level f the Central Chamber’s Stream System was lowered several feet stimulating vertical erosion in the river bed (Milestone, 1978).
Since the blasting, extensive field work on the El Capitan Moraine has taken place to better understand it. Specifically, this research collected three different GPR transects in the study area. GPR transects where chosen to record three different stratographic profiles of the moraine. Interpretation of the stratigraphy of these transects will be done with reference bed form patterns found in glaciated areas.
Ground penetrating radar (GPR) was the primary method used in this research. GPR uses electromagnetic (EM) radio waves that are the same frequencies broadcasted by radio towers. The GPR unit sends pulses of these waves into the ground via a transmitter. The EM energy is diffracted, refracted and reflected by different sediment layers and objects underground. The receiver unit detects the reflected waves and measures the amount of time the waves take to travel. The information received is then amplified and digitized by a computer in the field. The information can then be processed in the lab. The equipment used was a PulseEKKO 1000 GPR system. 100MHz frequency antennae were used in a step method with .25m intervals. The antenna and receiver were kept 1m apart at all times as the unit was moved across the survey tape incrementally. A TopCon RL-H3CL laser level was used to collect topographic information for each transect. The resulting information was used to geometrically correct the reflection profile. The GPR data and the laser leveling information was then loaded into Sensors and Software GPR PulseEKKO viewer, and preliminary processing was done. Adjustments were made to the trace to trace average. ACG gain was used and adjusted to enhance the display of the stratigraphy.
Pictured: Nick Topper (left) and Phil Larson (right) use the research equipment to study El Capitan Moraine.
The investigation of El Cap moraine included the collection of two transects perpendicular to the moraine as well as one cross line that ran parallel to the moraine on the downstream (west) side of the ridge. Transect R1 was located on to the north further away from the river. R1 is 100m in length and runs west to east over the top of the ridge and extends to the level ground to the East. Semi-continuous reflections were collected to a depth of 40m on the downstream side. Near the highest point in the moraine reflection die out at a depth of only 10m as the resistivity of the material increase likely due to elevated content of silts and clays. Semi continuous sub horizontal reflections are visible on the East side to shallow ¬¬¬depths. Three distinct sediment packages are viable including near surface deposits to a depth of 2m all the way across the transect. A second package of sub parallel semi continuous dipping reflections build up to a height of 8m and compose the moraine. They are underlay by semicontinuous hummocky features visible to a depth of over 40m which can be seen clearly until the 40m where the signal becomes attenuated.
Transect R2 shows reflections collected to a depth of 10m semicontinuous reflections are visible through out, the 50m transect which extends from the base of the east side of the moraine till the crest. Hummocky topography is present on the west (left) side till 40m. A continuous reflection appears at 2m of depth indicating top lap within this sediment package sub parallel semi continues reflections are found through with the exception of small sub parallel sigmoidal features present at 25m and 35m. Signal attenuation becomes strong at 45m in the deeper sediment package at 2m of depth.
Cross line C1 extends from 100m from North to South parallel to the moraine and perpendicular to the flow of the Merced River. Semicontinuous reflections extent to a depth of 40m on the north side. The profile contains two sediment packages delineated by a continuous reflection at 2m depth. The lower package has lenticular reflections that are semi continuous and extent from 0 to 90m where the signal is abruptly attenuated. The upper package has semi continuous sub horizontal reflections.
The Results from the GPR analysis indicate the internal stratigraphy of the El Cap moraine is consistent with the development of recessional moraines. The sub parallel reflections in R1 are dipping both to the east and west ¬in a convex shape similar to an antifoam. The antifoam begins at 30m and end at 65m extending to a depth of 8m. This pattern Is indicative of a recessional moraine and was deposited in an unsorted mass of sediment indicated by the wavy and chaotic stratigraphy at the center of the antifoam. The moraine is built on top of an older sediment package characterized by hummocky stratigraphy a continuous reflection can be seen dipping to the East at a depth of 8m. This package dies out at 40m but likely continuous through the transect. The hummocky stratigraphy can be interpreted as braided channel deposits from glacial-fluvial outwash during pre-Tioga glaciation. A third sediment package can be identified in the upper 2-4m on both the east and west side of the moraine. On the East side on lapping features extent from the 50m mark to 100m. Because the on lap is visible it indicates these reflections are composed of coarse grain sediments meaning they were likely not deposited by a stagnant shallow lake as previously hypothesized, but instead a more high energy process led to deposition. Large flood events are likely the mechanism of deposition, they still occur on an infrequent basis even though the local base level has been dropped by over 4m. Prior to the artificial manipulation the valley would have been more marshy and prone to flooding. On the west side of the moraine the upper 2-4m sediment package can be interpreted as fluvial deposits likely in the form of alluvial fans generated by flood events which overtopped the moraine. Sigmoidal reflections can be seen in R2 at 20-25m near the base of the moraine ¬¬and sub parallel reflections are seen thinning up hill. Transect C1 also contains a more recent sediment package just below the surface with 2m of thickness. The sediment package has sub parallel bedding at perpendicular angel to R1 and R2 indicating aggradation fluvial glacial process likely in the form of several small alluvial fans from over breach in multiple locations. The deeper sediment package in C1 is consistent with aggradation braided stream deposits seen in R1.