What is a hoodoo?
A hoodoo is a rock formation which is caused by differential

 resistance to erosion. This means that some parts of

the hoodoo are harder than others and these hard parts last longer

. In the hoodoos above, the tops are the hardest part

 and they protect the soft rock below from wearing away.

Hoodoos～The Southern Plains of Alberta

What is a hoodoo made of?
The hoodoos in the Milk River valley are made of sandstone

 which is sand-sized particles cemented together by calcite,

silica, or an iron oxide. Some sandstone is quite hard,

 but sandstone can be so soft that it brushes away when you touch it.

Hoodoos～The Southern Plains of Alberta

Hoodoos～The Southern Plains of Alberta

Hoodoos～The Southern Plains of Alberta

Hoodoos～The Southern Plains of Alberta

These sandstone layers have been exposed for over 15 thousand years.

During this time, they have been blasted, cracked,

and washed away by erosion.

For hundred of years, the Blackfoot people visited

 this valley and believed that this amazing place

 was sacred and the home of spirits.

Although it is rare for rock art to be found on hoodoos,

there are both pictographs and petroglyphs upon

 the sandstone cliffs along the Milk River.

Hoodoos ~

2013 06 29