The original sand was deposited in the channels of an ancient
river system around 65 to 56 million years ago. Today, these cliffs
are locally known as Raven Rocks, as this the first location that
Common Ravens were known to nest in Calgary.
The Porcupine Hills Formation sandstones are composed of
detrital quartz, chert, nonvolcanic rock fragments and clastic
carbonates. The heavy mineral assemblage is a residual suite of
small abraded grains of zircon, tourmaline and apatite. Only three
common intergranular mineral cements are present; quartz, kaolinite
and calcite. The bulk chemical composition of the Porcupine Hills
Formation sandstone is characterized by a low alumina and high lime
contents, and the predominance of potash over soda. (SOURCE:
Lithostratigraphy of the Uppermost Cretaceous (Lance) and Paleocene
Strata of the Alberta Plains by M.A. Carrigy, Bulletin 027, Alberta
Energy and Utilities Board)
You may observe Raven Rocks from other vantage points in west
Fish Creek Park. You may NOT access these cliffs from the top
(north) side, as the area is fenced off to protect this special
protection area (and park visitors). Other vantage points are down
in the valley. If you venture into the park, please remember to
stick to established trails to avoid damaging the vegetation.
NOTE: As of February 2007, several trails within Fish Creek Park
were still undergoing repairs as a result of damage caused by
extensive flooding in June 2005.
To log this cache, please complete the following:
- E-mail the cache owner (do not post) your estimate of the
length and thickness of this section of the Porcupine Hills
Formation plus any other observations you make regarding the
appearance of the cliff.
- Post a photo of your favorite view from this
viewpoint.
Click here to send
e-mail.