PHYSICAL MAKE UP
ge·ol·o·gy
the science that deals with the earth's physical structure and substance, its history, and the processes that act on it (Geology, Oxford Dictionaries, 2014).
BRIDGE CREEK, retrieved from Google (2014).
Everyone enjoys seeing a waterfall, they are esthetically pleasing. Bevis (2014) purposed the question, do we know why waterfalls occur? Tumalo Falls and Bridge Creek, provide outstanding examples of these geologic features. The earth’s crust is always changing, particularly
over the distance of a gradually deepening and lengthening stream valley (Bevis, 2014). Streams encounter multiple rocks and sediment types with different resistances to erosion by running water. Eventually, at some point along the stream’s channel, flowing waters begin to cut into resilient materials. Where the channel first succeeds in eroding through the resistant bed material and into a weaker substance below, erosion will continue slowly upstream and rapidly downstream (Bevis, 2014). Waterfalls are self-perpetuating, once the process has begun,
they may back-waste upstream at the nick point by erosion for great distances. According to Bevis (2014), a
thick dense basalt forms the cap rock which is underlain by less durable pyroclastic deposits, oxidized a reddish color by paleosol development. Weakening of the pyroclastics by the rushing water of the
falls causes “calving” of basalt blocks above and overall back washing of the
valley and head ward erosion. The creation of Tumalo Creek and the waterfall,
Tumalo Falls was aided by glacial erosion. The waterfall has probably cut
head ward by several hundred feet since de-glaciation of the drainage roughly
20,000 years ago (Bevis, 2014).
LOCATION INFORMATION
("Bridge Creek Falls", 2014)
Image
Bevis, K. (2013).
Map 1E.3. Color shaded-relief map of the Tumalo Falls 7.5” Quadrangle containing segments of Field Trip 1D and Field Trip 4B.[jpg]. Retrieved from http://intheplaygroundofgiants.com/?page_id=372
("Bridge Creek Falls", 2014)
- Latitude 44.03028 N
- Longitude -121.58028 W
- Elevation 5285 feet
- USGS Quadrangle Tumalo Falls 7 1/2"
Image
Bevis, K. (2013).
Map 1E.3. Color shaded-relief map of the Tumalo Falls 7.5” Quadrangle containing segments of Field Trip 1D and Field Trip 4B.[jpg]. Retrieved from http://intheplaygroundofgiants.com/?page_id=372
SOIL:
The soil resource is ruled by ash and pumice from Mt. Mazama on the surface (Tumalo Creek Watershed Analysis, 2008). The sub-surface is made up of glacial till and other localized volcanics. the sub surface is general a course material with a low cohesion properties (Tumalo Creek Watershed Analysis, 2008). The sub-surface materials on the eastern edge of the watershed contain basaltic lavas and glacial out wash. "Greater amounts of cinder, colluvium, and residual buried soils present themselves in the sub-surface of the western half of the watershed, as the lands are lacking fruitful soil materials" Tumalo Creek Watershed Analysis, 2008, p. 10).
SOIL QUALITY:
Soil erosion has been amplified by the removal of vegetation from slopes the bank streams. According to Bevis (2014),
"The eroded soils are what caused excessive sedimentation in the stream channel. This resulted in a reduced channel gradient and braiding of the stream channel, and overall flattening of the valley floor. Unfortunately, this redistribution of floodplain materials led to damaging impacts on the stream ecosystem, including degraded water quality, wetlands, and both aquatic and terrestrial wildlife" (para. 5).
According to Tumalo Creek Watershed Analysis (2008)
The inherent productivity of the soils is:
moderate-50%-(18,942 acres),
low-27%-(10,225 acres),
high-22%-(8209 acres),
and barren-1%
Soil productivity is influenced by things such as annual precipitation, elevation, aspect and soil profile depths. According to Tumalo Creek Watershed Analysis (2008) each can be limiting with in the watershed.
INFORMATION FOR THE PHYSICAL MAKE UP OF BRIDGE CREEK
("Bridge Creek Falls", 2014)
Height-25 feet
Tallest Drop-25 feet
Num. Drops-1
AVG. Width-10 feet
Pitch-90 degrees
Run-1feet
Primary Form-Plunge
Watershed-Deschutes River
Stream-Bridge Creek
AVG. Volume-75.0 cfs
Source-Springs
Seasonality
Best Flows-Year Round
The soil resource is ruled by ash and pumice from Mt. Mazama on the surface (Tumalo Creek Watershed Analysis, 2008). The sub-surface is made up of glacial till and other localized volcanics. the sub surface is general a course material with a low cohesion properties (Tumalo Creek Watershed Analysis, 2008). The sub-surface materials on the eastern edge of the watershed contain basaltic lavas and glacial out wash. "Greater amounts of cinder, colluvium, and residual buried soils present themselves in the sub-surface of the western half of the watershed, as the lands are lacking fruitful soil materials" Tumalo Creek Watershed Analysis, 2008, p. 10).
SOIL QUALITY:
Soil erosion has been amplified by the removal of vegetation from slopes the bank streams. According to Bevis (2014),
"The eroded soils are what caused excessive sedimentation in the stream channel. This resulted in a reduced channel gradient and braiding of the stream channel, and overall flattening of the valley floor. Unfortunately, this redistribution of floodplain materials led to damaging impacts on the stream ecosystem, including degraded water quality, wetlands, and both aquatic and terrestrial wildlife" (para. 5).
According to Tumalo Creek Watershed Analysis (2008)
The inherent productivity of the soils is:
moderate-50%-(18,942 acres),
low-27%-(10,225 acres),
high-22%-(8209 acres),
and barren-1%
Soil productivity is influenced by things such as annual precipitation, elevation, aspect and soil profile depths. According to Tumalo Creek Watershed Analysis (2008) each can be limiting with in the watershed.
INFORMATION FOR THE PHYSICAL MAKE UP OF BRIDGE CREEK
("Bridge Creek Falls", 2014)
Height-25 feet
Tallest Drop-25 feet
Num. Drops-1
AVG. Width-10 feet
Pitch-90 degrees
Run-1feet
Primary Form-Plunge
Watershed-Deschutes River
Stream-Bridge Creek
AVG. Volume-75.0 cfs
Source-Springs
Seasonality
Best Flows-Year Round
