Geobulletin alpha

News from the Geoblogosphere feed

by Stratigraphy.net
New from Snet: Lithologs, a new tool to create lithological/sedimentological logs online..

Blog post recommendation

To Ski…Or Not To Ski?

Spring has sprung at last, but it seems as though it has been here for months already. Usually, snow can linger well into summer, up on the high plateaus of southern Utah. Several weeks ago, two friends and I hoped it would last at least through the middle of March. We wanted to ski, and we wanted to ski at Bryce Canyon. To ski you need snow, and there has been a noticeable lack of it this winter. Temperatures have been higher than average here in Utah, with conditions great for hiking but abysmal for skiing (click here for that story). The generally thick blanket of snow we know so well had morphed into slightly more than a veneer. We could only hope for the best as John, Cathy, and I stuff our skis, suitcases, and snack items into the back of my car and drive off in wild anticipation of the miles of cross–country ski trails that Ruby’s Inn grooms just outside the Park. We would spend two nights at the Inn and get in as much skiing as our little hearts desired.
Sunset Point, Bryce Canyon National Park
We arrive at the Inn and try to check in three and a half hours early. The desk clerk very politely but firmly informs us that this is impossible since our adjoining rooms (with a requested connecting door!) are not ready. He calmly explains that check–in is at 4pm but that we might be able to check in at 2:30. Could we come back in a couple of hours? We are in no hurry. The dining room and a leisurely lunch beckon.

Options
 
After enjoying a tasty repast, I flash my geezer pass at the Bryce Canyon entrance station and motor onward to the visitor center. Although it is a Monday in March, the parking lot is full and the visitor center is mobbed. I can hardly spin the postcard carousel without bumping my butt into someone who is thumbing their way through a spiral–bound copy of “Wagon Recipes of the Pioneers” or deciding which refrigerator magnet would look best with their great–uncle’s kitchen décor. Excuuuuuse me! John and Cathy jostle their way through the crowd to the video display, picking up three of the same southwest videos to give to relatives living back East. Do they live near each other? I inquire gently of my friends. You might want to consider buying them each different ones in case they get to comparing gifts. That sort of family confrontation could get ugly.
 
By now it is 2:30 so we go back to the motel to try our luck at checking in again. Nope. Not ready yet! We are told to come back at 4pm and all will be well. We dither about, discussing our options. Thinking we may need them, we dig our snow boots out from beneath a mountain of Russell Stover’s dark chocolate–covered coconut eggs and head for Sunset Point and our first view of Bryce Canyon in winter splendor. Skiing is beginning to look less and less desirable as daylight burns.

Not a bad view from behind the railing. Table Cliffs with Powell Point in distance.
At the overlook we could only shake our heads in disbelief when we notice where someone (or sometwo or somethree) with severely impaired judgment skills has hopped over the railing onto a snow–covered slope of dubious footing and uncertain angle of repose.

I'm not hopping over any railing!
The hoodoos are a testament to the power of weathering and erosionHoodoos, fins, pinnacles and towers - it all comes down to water 
We mosey around at the overlook and dither some more about our plans. To ski or not to ski? Our good intentions are rapidly melting away like a snow bank in a late winter heat wave. The sun is slowly going down over the yardarm (wherever that is). We reinstall ourselves into my car and nestle comfortably between the mountain of coconut eggs, snacks, skis, poles, boots, and other paraphernalia of cross country skiing. I make an executive decision and turn left out of the parking lot. The die is cast. We will drive up to the end of the Park road and stop at overlooks on our way down. We all breathe a sigh of relief. Tomorrow we will have all day to ski unless we talk ourselves out of it.

Our first unscheduled stop on the way up the scenic drive is Bryce Point, where the Park has done a fine job of snow removal in the parking lot. However, deep snow and slick ice cover the path to the overlook. We ignore any temptation to stroll out for a look, enjoying the view from a safer vantage. Other folks, it seems, were not so cautious. Either they (1) have no common sense, (2) cannot read English, or (3) figure the signs do not apply to them, hopping over the railing and possibly giving Bryce Search and Rescue the opportunity to come out of their warm cabins to practice their skills.

The namesake viewpoint is closed due to snow and ice dangerSome people did not get the memo
The view is quite good from the parking lot.
Frozen or otherwise, it is all about the water
 
We make our way to Rainbow Point and the end of the Park road, braving the chilly late winter wind to stand and contemplate the wonder of it all. Why does Bryce Canyon even exist? It is not even really a canyon. It is technically an amphitheater, a somewhat circular landform partly surrounded by steep slopes, carved over millions of years into the eastern edge of the Paunsagunt Plateau. Deposition, uplift, and erosion all come in to play to create the fantastic scenery. Fractures form, weakening the strength and stability of the bedrock. They are the conduits by which water reacts with the ground. In the end, water is Bryce Canyon’s most significant element of weathering and erosion, its creative force and the accelerator of the its ultimate undoing.

Panorama from Rainbow Point

Overnight temperatures this week are in the teens. During the day, solar radiation takes over and the thermometer reaches into the low 30°F range. What effect do these temperature fluctuations have on the rocks here?  Geologic processes are at work right before our eyes, awake or asleep.

What sculpting do you see in the balanced hoodoos?
Resistant limestones cap softer siltstones and mudstones
The effect is the landscape of hoodoos. The cause is freeze–thaw cycles, working the fractures into submission until the rocks crumble, gradually enlarging the spaces between them. Criss–crossed fractures are particularly susceptible – the more surface area that is exposed, the more intense the weathering. During the subfreezing winter nights, ice particles pack the fractures. During the warmer daytime hours this ice thaws, destroying the rock surface grain by grain.

But freezing and thawing are not the only ingredients in water’s bag of tricks. Torrential monsoon rains of late summer are capable of eroding away vast amounts of debris leftover from a winter of weathering. Estimates of the rate of westward erosion of the amphitheater hover around four feet per century. Headward erosion of the Paria River and its tributaries is carrying Bryce Canyon away to the Colorado River and beyond.

Headward erosion chews into the rim of the amphitheater
We have come to play in the snow and enjoy a tour of Bryce’s winter wonderland. The landscape is weathering before our eyes. Questions remain.

Will we make it out alive before the amphitheater erodes completely?

When exactly does the sun go down over the yardarm?

Will we ever put on those skis?

We are nothing if not flexible!********************************************************************************* I do not make this stuff up, and I certainly hope I get it right. My invaluable geologic resource is:
Sprinkel, D.A., Chidsey, T.C., and Anderson, P.B., editors, 2000, Geology of Utah’s Parks and Monuments, Utah Geological Association Publication 28












Stratigraphy.net | Impressum
Ads: