navigator wall rock composition

[tyree]

I was wondering what type of rock was prevalenton the Navigator Wall?? Does any body know or know somebody who knows? Thanks in advance- tyree

[crazyjizzy]

The latest geologic map which I have (Tabor and others, 2002)which only covers to the border, shows intrusive rocks of the Chilliwack Batholith. That said, Beckey mentions dioritic rocks. Need to know more?

[Andrew_R]

I talked to a friend recently who was a good friend of Guy and John's (who'd climbed the navigator) and apparently they said "it was fine just a little run out in places"... I didn't ask for more info... I'm a bit more interested in the east pillar but I'm sure it would be a good route too. I hope u crank it

[John Frieh]

Does any body know or know somebody who knows?

 

Word up... anybody know somebody who has climbed this?

[tyree]

I havent been up to slesse yet but from what I have heard the north rib is primaraly composed of some granite, NE but is some sort of choss or another so it seems to be a mixed bag. i was hoping to hear it was mostly granite but i guess we'll find out soon. thanks for the info and if yall hear any more id be interested in hearing about it.

[forrest_m]

the east pillar is almost entirely diorite (or whatever the non-granite on slesse is), though the lower buttress toe (to the top of the first pitch per mclane) is granite. my impression is that nav. wall. is similar. northeast butt. is strange, mostly granite down low and on the right (north) side, but the joint with the diorite is right on the crest on the upper half of the route.

 

despite not being granite, the diorite is not pure choss, either; on the e. pillar, it was pretty solid, with lots of edges, but without long continuous crack systems. we did a lot of face climbing to connect small corners, flakes and whatnot. we placed a lot of smaller cams and were happy for the fixed pro. again, nav. wall appears to be similar.

[Bigwall]

Sorry. What was I thinking?! My post beginning with "I believe Beckey describes the non-granite rock on NEB of Slesse as "granodiorite" was way off the mark. Apologies to Tyree. Thanks to Crazyjz and Dru for the accurate info.

Edited July 11, 2005 by Bigwall

[crazyjizzy]

Granodiorite is lumped by many petrologists as "granite". Grain size is independent of mineralogy. Brittleness is dependant on a whole range of factors, as are crack ststems. As a first order assumption, one couls assume that the dioritic rock are probably older, and as such were affected by the emplacement of the younger acidic rocks in such a way to cause more jointing and incipient cracks. These will preclude the development of larger/longer crack systems. This is only an easy model.

[tyree]

well thanks again, that was very educational.

I guess that we will find out soon if the weather cooperates. if anybody does know 1st hand i would be stoaked on some rock beta.

[j_b]

hmm, the rock on the upper half of the NE buttress doesn't look igneous intrusive to me (but i could be wrong), by opposition to the lower part which is some kind of diorite. There are chunks of terranes older than the plutons all over the North Cascades and my not very detailed geologic map of the area shows that part of slesse is some kind of metamorphic rock.

[Dru]

Slesse consists of a variety of rock types, separated from each other almost vertically. From east to west one goes through Chillwack Batholith then several older rocks ending up with Carboniferous-aged (IIRC) metamorphics on the west side.

 

The Navvy Wall is Chilliwack Batholith granodiorite on the bottom and metamorphic on the top.

 

See photo below...

[Dru]

 

Flight 810 Buttress at left and South Peak East Face at right

Navvy Wall route line in red

Geologic contacts an approximation

Lithology from personal experience and the geologic map of the area.

The gneiss is really just the most metamorphosed part of the phyllite, the two are really the same geologic unit but the gneiss has undergone greater metamorphism along the Chilliwack Batholith contact, IMHO anyways.

[Dru]

Roughly speaking the geologic contacts, are at the top of p6 and p15, respectively, if using the belays marked in the Beckey topo. Also the start of the red line that I drew differs from the topo start, which would go up from the snowpatch, to and through the B in Batholith, and then trend right along the ledge that the first geologic contact follows.