The Cache la Poudre River originates in Rocky Mountain National Park in Colorado and flows east through Roosevelt National Park, descending over 7,000 feet before joining the South Platte River. The canyon has been home to Native Americans for centuries, with evidence of their presence such as fire hearths, burial sites, and rock shelters. Igneous rocks form by the cooling and solidification of magma or lava, either below the surface as intrusive rocks or on the surface as extrusive rocks. Sedimentary rocks form through the deposition and compaction of sediment and cementation over time. Metamorphic rocks are formed when rocks are subjected to heat and pressure, causing them to change form.

1. Joseph Contreras

2. Cache la Poudre River
 The Cache la Poudre River or the Poudre River as locals
refer to it originates in the Rocky Mountain National
Park in Colorado and flows into the South Platte
River. Located east of the continental divide in the
northern front range of Colorado, the river travels 126
miles east through Roosevelt National Park and
descends over 7,000 feet.
 The canyon has been home to native Americans for
centuries. Evidence of their presence such as: fire
hearths, burial sites, tipi rings, and rock shelters have
been located in the canyon.

3. Igneous Rocks
 Igneous rock is formed by the cooling and
solidification of magma or lava. Igneous rocks can
form below the surface as intrusive(plutonic) rocks or
they can form on the surface as extrusive(volcanic)
rocks.

4. I believe this to be an igneous rock. It has the characteristics of
basalt. Basalt is an intrusive rock which is fine grained and typically
dark in color.

5. Sedimentary Rocks
 Sedimentary rocks are formed by the deposition of
material at the Earth’s surface and within bodies of
water. Sediment is produced when preexisting rocks
are broken down by weathering processes. This
sediment then moves by various forces such as: gravity,
water, wind, and glacial ice. Over time the layers of
sediment succumb to the forces of compaction and
cementation to form rock.

6. I believe this to be a sedimentary rock. The various layers of
sediment are easily scene. The rock appears to be a dark sandstone
with rings or clay.

7. This appears to be heavily weathered sandstone. The rock
contains uniform sand sized grains throughout.

8. Metamorphic Rocks
 Metamorphic rocks are formed when an existing rock
is subjected to intense heat and/or pressure. The
parent rock of a metamorphic rock may be an igneous,
sedimentary, or even a metamorphic rock. Pressure
from within the Earth or tectonic processes may cause
a rock to change.

9. I believe this to be a metamorphic rock. Gneiss is what this rock
likely is. Gneiss are medium to course grained banded rocks. I can
see this rock once had clear bands but it appears these bands have
been broken by forces of heat and pressure.

10. This rock is weathered and dull in appearance, however I do believe
it is a type of quartzite. Sandstone is the parent rock to quartzite.
This one seems to contain iron oxide.

11. References
National and Wild Scenic Rivers
http://www.rivers.gov/wsr-cache-la-poudre.html
Wikipedia
http://www.wikipedia.org/
Tarbuck and Lutgens, Earth: An Introduction to Physical
Geology, 10 th Edition, Prentice Hall (2011),