Essay Describe Two (2) Major Environmental Changes That Have Affected The Sacramento River
ESS 50
Homework 3 (20 points)
Homework assignments should be typed. For questions that require you to sketch something, you can turn in the sketched part of the assignment to the TA at the start of class, take a photo of your sketch and embed it into the assignment, or sketch it using software such as Powerpoint, Preview, or the various Adobe products (and likely many, many other programs). All assignments should be turned in online by the assigned due date and time. It is your responsibility to turn in your assignment on time. Please write in complete sentences, check spelling and grammar, and be sure to answer the questions!
(7 pts) 1. Explain why the granite rocks of the Sierra Nevada are visible today and not covered by metamorphic rocks. What major force(s) were involved in exposing the rocks?
- …show more content…
Granite rocks of the Sierra Nevada are visible today because they are remnants of metamorphosed sedimentary rocks from the ancient shallow sea which are so called “roof pendants”. Roof pendants are a downward projection of country rock into a batholith which is an igneous intrusion The granite rocks which are visible are remnants of the rock into which the molten granitic material penetrate and are metamorphosed by the resulting heat and pressure. As mountains arose, the molten rocks formed beneath them. The molten rock eventually cooled and solidified into the granite which are visible. The rocks which are now exposed in foothill belt include slate, limestone, greenstone and serpentines. They aren’t covered by metamorphic rocks because the roof pendants which lean on the granite rocks and exposes them and push the metamorphic rocks inward. The major forces which are involved in exposing the three type of rocks. These rocks all link to the process that change one rock type to another. All igneous rocks began as magma which cools and crystallize into minerals. For example magma that cools slowly creates rocks like granite. After the rocks are formed the rock pieces, called sediments, drop from the wind or water to make a layer. Over time it can cement together to make sedimentary. Lastly the metamorphic rock is formed by either rocks under heat and pressure. Together these rocks all go hand in hand as a major force.
(7 pts) 2.
Describe two (2) major environmental changes that have affected the Sacramento River since 1850. Include in your description the ecological or hydrologic effects of these changes on the river system (e.g., impacts on particular species, physical properties of the river, etc.).
- Two major environmental changes that have affected the Sacramento River include hydraulic mining and agricultural development. Hydraulic mining is a form in which uses high pressured jets of water to move sediments or remove rock material. This tripled the sediment load in the Sacramento River for around 100 years which allowed 1.3 billion cubic yards of sediment to enter the river. This diminished the ability of the river to carry water and increased flood frequency. Hydraulic mining also ruined farmland because of this. With agricultural development, it allowed for “tule lands” or reeds along the river to be developed which was 500,000 acres along the river. Agricultural development also supported vast riparian forest which was 800,000 acres along the river. Change of the land to agriculture transferred ownership to private land owners which ended up restricting public
access.
(3 pts) 3. What is a wetland and what are two types of ecosystem services that a wetland provides?
- Wetlands are permanently or periodically flooded lands, adjacent to rivers or basins. These are areas where water covers the soil, or is present at or near the surface of the soil all year or for periods of time during the year which includes the growing season. Two types of ecosystem services are flood control and water purification.
(3 pts) 4. Which lake used to be the largest body of fresh water west of the Great Lakes? Why isn’t it around today?
Homework 3 (20 points)
Homework assignments should be typed. For questions that require you to sketch something, you can turn in the sketched part of the assignment to the TA at the start of class, take a photo of your sketch and embed it into the assignment, or sketch it using software such as Powerpoint, Preview, or the various Adobe products (and likely many, many other programs). All assignments should be turned in online by the assigned due date and time. It is your responsibility to turn in your assignment on time. Please write in complete sentences, check spelling and grammar, and be sure to answer the questions!
(7 pts) 1. Explain why the granite rocks of the Sierra Nevada are visible today and not covered by metamorphic rocks. What major force(s) were involved in exposing the rocks?
- …show more content…
Granite rocks of the Sierra Nevada are visible today because they are remnants of metamorphosed sedimentary rocks from the ancient shallow sea which are so called “roof pendants”. Roof pendants are a downward projection of country rock into a batholith which is an igneous intrusion The granite rocks which are visible are remnants of the rock into which the molten granitic material penetrate and are metamorphosed by the resulting heat and pressure. As mountains arose, the molten rocks formed beneath them. The molten rock eventually cooled and solidified into the granite which are visible. The rocks which are now exposed in foothill belt include slate, limestone, greenstone and serpentines. They aren’t covered by metamorphic rocks because the roof pendants which lean on the granite rocks and exposes them and push the metamorphic rocks inward. The major forces which are involved in exposing the three type of rocks. These rocks all link to the process that change one rock type to another. All igneous rocks began as magma which cools and crystallize into minerals. For example magma that cools slowly creates rocks like granite. After the rocks are formed the rock pieces, called sediments, drop from the wind or water to make a layer. Over time it can cement together to make sedimentary. Lastly the metamorphic rock is formed by either rocks under heat and pressure. Together these rocks all go hand in hand as a major force.
(7 pts) 2.
Describe two (2) major environmental changes that have affected the Sacramento River since 1850. Include in your description the ecological or hydrologic effects of these changes on the river system (e.g., impacts on particular species, physical properties of the river, etc.).
- Two major environmental changes that have affected the Sacramento River include hydraulic mining and agricultural development. Hydraulic mining is a form in which uses high pressured jets of water to move sediments or remove rock material. This tripled the sediment load in the Sacramento River for around 100 years which allowed 1.3 billion cubic yards of sediment to enter the river. This diminished the ability of the river to carry water and increased flood frequency. Hydraulic mining also ruined farmland because of this. With agricultural development, it allowed for “tule lands” or reeds along the river to be developed which was 500,000 acres along the river. Agricultural development also supported vast riparian forest which was 800,000 acres along the river. Change of the land to agriculture transferred ownership to private land owners which ended up restricting public
access.
(3 pts) 3. What is a wetland and what are two types of ecosystem services that a wetland provides?
- Wetlands are permanently or periodically flooded lands, adjacent to rivers or basins. These are areas where water covers the soil, or is present at or near the surface of the soil all year or for periods of time during the year which includes the growing season. Two types of ecosystem services are flood control and water purification.
(3 pts) 4. Which lake used to be the largest body of fresh water west of the Great Lakes? Why isn’t it around today?