Hiking to Castle Rock – Blue Joint Wilderness Study Area

Located within the Blue Joint Wilderness Study Area, Castle Rock is easily one of the most recognizable features in the Magruder Corridor. The bare prominence stands boldly above the ridge that stems southward from Nez Perce Pass. The actual “castle” of Castle Rock is a mass of porphyritic andesite, a highly durable volcanic stone. So, the core of Castle Rock is a long extinct volcano from which the outer layers have long since eroded away leaving the andesite core.

The hike goes generally upwards until you reach the base of Castle Rock with first 1/2 mile steeply ascending to a subtle junction with the Castle Rock trail, which is to the left. A small sign several yards up this trail simply states “Castle Rock”. The path cuts through a rather pleasant meadow and along a ridge. At the base of Castle Rock, several widely-spaced cairns mark the path to the summit (look for the arrow cairn). From here, we picked our way on the talus and climbed a couple of small cliffs. Once on top, a sizable cairn marks the summit. A simple strand of prayer flags had been placed on top of the cairn.

Total distance: 5.83 mi
Max elevation: 7726 ft
Download
Go to the left at the Y. Why? Because you're supposed to.

Go to the left at the Y. Why? Because you’re suppose to.

Yep, the right trail

Yep, the right trail

Loved hiking through this meadow

Loved hiking through this meadow

I bet the elk love this place

I bet the elk love this place

Vida approaching the timbered ridge

Vida approaching the timbered ridge

Descending down to the saddle before the "real" up

Descending down to the saddle before the “real” up

First unobstructed view of Castle Rock

First unobstructed view of Castle Rock

View of the summit cairn of the ridge

View of the summit cairn of the ridge

Castle Rock rises steeply from here

Castle Rock rises steeply from here

Go this way, unless you want an adventure route

Go this way, unless you want an adventure route

You're doin' good!

You’re doin’ good!

Scrambling over the talus and boulders to the top

Scrambling over the talus and boulders to the top

Prayer flag at the summit cairn

Prayer flag at the summit cairn

Porphyritic andesite

Andesites are fine-grained, extrusive igneous rocks that are usually light to dark gray in color. Porphyritic refers to andesites that have two crystal sizes. When the magma erupts, large crystals form slowly at depth (known as “phenocrysts”), and small crystals form quickly at the surface. Geek moment over.

Magruder Corridor

The Magruder Corridor is 101-mile primitive road winds through a vast undeveloped area. The road itself is sandwiched between the Selway-Bitterroot Wilderness to the north and the Frank Church-River of No Return Wilderness to the south.
On the border of Montana and Idaho, Nez Perce Pass marks the descent into the Magruder Corridor

On the border of Montana and Idaho, Nez Perce Pass marks the descent into the Magruder Corridor

Written by Radd Icenoggle

I am a native Montanan, who has spent a lifetime as an outdoors and wildlife enthusiast. I earned a degree in biology with an emphasis on habitat relations. During my studies, I had the great fortune to research and compose a thesis that explored the effects of slope aspect on...
Read more

Leave a Reply

Your email address will not be published. Required fields are marked *