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Colorful lichens on quartz...

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Colorful lichens on quartz sandstone amongst the solid granite that Mount Morrison is made of. North Ridge Route, Summer, 2003.
Photo by Aaron Johnson

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JonBradford

Granite?

Hasn't voted

Aaron that is not granite. If it was found on the lower slopes of Mount Morrison it is likely Quartz Sandstone (quartzite) from the Fountain Formation. The Idahu Spings Formation which is the metamorphic/igneous member that comprises much of the body of Mount Morrison does have some granitic pegmatites but the bulk of the rock is composed of greyish gniess. Jon

Posted Mar 8, 2004 9:33 pm


	desainme	Re: Granite?
	Voted 10/10	Jon this stuff looks like the rock at Devils Lake Swissconsin which is sandstone quartzite too.
		Posted Mar 8, 2004 9:59 pm


	Aaron Johnson	Re: Granite?
	Hasn't voted	Jon-I figured it was granite because it is so high up on the mountain, well above the Fountain Formation, atop the North Ridge, actually. If you think I should change the caption, I'll do so. You get around pretty good-it would be a great excuse for you to look at the rock on the North Ridge yourself. I would certainly defer to your opinion as you are more focused on the geology aspect than I am. Let me know what you think.
		Posted Mar 9, 2004 5:58 pm


	Aaron Johnson	Re: Granite?
	Hasn't voted	Jon, I've adapted the caption-let me know if you want to check this out or have it go at that.
		Posted Mar 9, 2004 6:04 pm


	JonBradford	Re: Granite?
	Hasn't voted	Aaron, As I have never explored the north ridge of Mount Morrison I can't be certain. The contact between the Idaho Springs formation (the above mentioned formation that is Colorado's 3.8 billion year old basement rock and forms the bulk of Mount Morrison) and the Fountain Formation (the 300 million year old sandstones/mudstones/siltstones that form the main portion of Red Rocks park) is just across from the upper parking lot at Red Rocks. So the fact that your rock is found high on the north ridge is either not a sandstone of the Fountain Formation (an that means I am wrong, entirely possible), or if it is, it is a remanent left by the erosion that scoured the overlying sedimentary layers from the underlying basement rock (this would not be unusual, near Vail Pass, bits of the Fountain Formation crown many of the ridges). I am pretty certain of my visual identification though. Near Boulder the Fountain Formation does reach up into the foothills to crown South Boulder and Bear Peaks so it would not be unusual to find these rocks near the summits of the adjacent foothills. Indeed your photo reminded me of the rocks near Bear Peaks summit and I know those to be part of the Fountain Formation. If you want me to confirm this I guess I could run up the mountain sometime soon... Jon
		Posted Mar 9, 2004 8:27 pm


	Aaron Johnson	Re: Granite?
	Hasn't voted	Jon-Your point about the Fountain Formation near Shrine Pass is well taken. I have the Shrine Mountain page and refer to it! I had forgotten about Bear Peak's summit being made of the same material. I'm inclined to go with you on this, save for that 10% uncertainty because the rock on the Morrison North Ridge was all by itself (as I recall, but I am getting old). I'll leave the edited caption as is and if you get the chance (and desire) to get it out, have at it. I'll send you an email that indicates the rock's general location. I would head back up there, but you would know better than I would.
		Posted Mar 9, 2004 9:43 pm