Wasatch Geography Question

So here's a question that I've been thinking about for a while and was hoping that someone with more geology and geography knowledge might know the answer to: Why is the northern Wasatch (say... everything north of Lone Peak) so much more rugged than the southern Wasatch (say... from Timp to Nebo)? Sure, the southern Wasatch has rugged canyons, but I guess I'm talking about the mountains themselves.

This all started when I was trying to think about any alpine rock ridge routes in the southern Wasatch, and I couldn't really think of any. Then I started thinking of each individual big mountain down here and they're just... more rounded than their northern brothers.

While we're on the topic, does anyone have any more interesting Wasatch geology/geography tidbits?

-Tristan

Someone please correct this if I am wrong. My guess would be that it has to do with rock types. North of Lone Peak the rock types are mainly granite (or quartz monzonite) and quartzite. Timp and south are quartzite shale and limestone. Different types of rock weather in different ways leading to different formations.
If any of this is wrong please correct me. My degree is in geography but my specialty is in cartography not geomorphology.

SuperT, that sounds plausible.

Tristan, I was in Provo last week and was wondering the same thing. I am glad you brought it up, to remind me to research .

Here is an interesting brochure on the Wasatch. It is interesting that the Wasatch was formed by the plate moving past the Yellowstone Hot spot.

geology.utah.gov/online/pdf…

I am going to call the phone numbers at the end of the brochure to talk to a geologist.

I read about this in a geology textbook once. I think they said it is partly due to rock type like Super T said, but also due to the differing ages of uplift. Apparently the Provo River is one of the oldest in the state, and was there carrying water from the Uintas long before the Wasatch orogeny.

You might like one of the many 'geology of Utah' books available. The bookstore at your school has some really great references on it. (I didn't sell mine back). You'd get some really interesting answers from some of the professors there. Those guys have such a broad understanding of it all.

And then there may be answers here

I am glad to see that Super T and Tenesmus are backing up my original thoughts when Tristan originaly asked me this question during a hike. Rock types/ages and weathering/erosion paterns all seem to change for each segment of the wasatch fault. Each segment moves independent of the others, which could cause lots of differences.
Tenesmus, I also love that you used "orogeny" in a sentence found on a climbing website! I have gained much resect for you...

Hey guys...nice discussion, I've got a buddy who explained this to me once. I'll kick him over an email and get the skinny for you all.

below is the email I received in response.
The "simple" answer has three parts.

First part is the section between American Fork canyon and Big Cottonwood canyon. The "ruggedness" of this area is largely caused by a big igneous intrusion called the Alta Stock. It is a huge blob of molten lava that came up near the surface (but never broke through the surface as far as we know) about 20 million years ago. This magma cooled beneath the surface and then became exposed at the surface through faulting and erosion and is the now seen as the granite of Lone Peak and Little Cottonwood Canyon; which the SLC LDS Temple was made of).

Second part is the Uinta Arch. If you look on a map you'll see the Uinta Mountains run east/west from the Utah/Colorado border to about the Kamas area. The truth is however, the huge east/west running upfolded chunk of earth that creates those mountains does not really stop at Kamas, it just has a little break in it. The fold actually begins again just west of Park City and continues west to at least the Tooele area. However, from the Wasatch Front to Tooele the arch/upwarp has been dissected or cut to pieces by Basin and Range faulting so it is mostly dropped and buried beneath the Salt Lake Valley. But if you Look at Mount Olympus from I-15 or head up Parley's canyon you'll see that the rocks in that area are steeply dipping (almost vertical) down to the north. That's the North Flank of the Wasatch section of the Uinta Arch (fold). If you go down to American Fork Canyon you'll see the opposite. The strata there is generally dipping steeply down to the south because it is the south flank of the Wasatch section of the Uinta Arch. The fact that the Wasatch Fault Cuts perpendicular to folding in this area makes for many major canyons running east/west and adds to broken up/rugged look of the segment of the Wasatch Front through salt lake county.

Now to further explain what I'm saying above, for most of the Wasatch Front, the mountain face, which has been created by the Wasatch Fault is fairly smooth because the Wasatch Fault has cut parallel to pre-existing folds (Utah Valley is a good example, if you go to the Bridal Veil Falls area or Rock Canyon you'll see that there's actually a huge fold running parallel to the Wasatch Fault under Temp. Mtn and Provo Peak. This kind of geomorphology creates long thin north/south sections of mountain that have north/south running canyons just behind them (Temp. Mtn/Alpine Canyon, Provo Peak/S. Fork Provo river/Round Valley, Farmington Mtn/East Canyon). As explained above, the Salt Lake County section of the Wasatch Fault runs perpendicular to pre-existing folding (because of the Uinta Arch), which creates more numerous east/west running canyons (corner canyon,N&S cottonwood, Mill canyon, Parley's, Emigration, Red Butte, City Creek). This is compounded with the large surface area of east/west trending ridge-lines that these east/west running canyon's create which makes for large north slopes which created the best accumulation zones for glaciers during the last ice age, which glaciers in turn added even more to the ruggedness.

The last of the three parts is a layer called the Tintic Quartzite. I'll cut this short by just saying that where "it" is.... "ruggedness" is also. And it is in abundance in the Ben Lomond Peak area north of Ogden. It is also seen in bits and pieces in Big Cottonwood Canyon and Morgan Canyon. nuff said.

Hope that is understandable. If you have questions call or visit me at the Utah Geological Survey. 801-537-3346. It is our job to answer public inquires like this. :)

So the Uinta Arch is juxtaposed with the Wasatch Fault exposing the granite created by the Alta Uplift, with north facing glaciation and quartzite bands further changing the look and feel of individual canyons. Pretty cool stuff!

Thanks for the geomorphologic explainer.

Do they have a website with more info on this stuff? I looked around a little but didn't come up with anything in this detail or clarity.

Thanks for the info.

Awesome! Thanks for the info. I was just wondering about the granite in the Lone Peak area, but couldn't find anything online.