Geobulletin alpha

Source info:

Author:
Date:	2015-04-20 05:42:19
Blog:	WATCH FOR ROCKS - Travels of a Sharp-Eyed Geologist
URL:	http://www.watchingforrocks.com/2015/04/cant-get-enough-of-canyonlands.html

Summary:

For someone who can’t get enough of a place, I certainly don’t go there very often. I went maybe thirteen years ago to visit friends living in Moab, Utah, and to watch the Perseid meteor shower on a moonless night in Arches National Park. It is not that far from my home, really, as far as western distances go – just over 300 miles away, barely five hours and change. My friends still live there. Shafer trail takes off near Island in the Sky visitor center - La Sal Mountains in distanceTime gets away from us, though. Life happens. I don’t know what took me so long to return, but I knew that I wanted to reconnect with my old friends once again. I also hoped to hike in Canyonlands, if only for a few hours. With all that in mind, I chose a weekend to invite myself and made it happen.Massively vertical cliffs of Wingate Sandstone dominate the Island in the Sky areaLee had to work, but Alicia was happy to oblige. She is a patient soul, delighted to show me her side of our state and more than willing to indulge this geology geek’s passion for photographing rocks. We were in absolutely no hurry on this gorgeous early spring day.The incised meander of the Green River (upper left) courses through Canyonlands Just as the Navajo Sandstone does in Zion National Park, the Wingate Sandstone forms massive vertical cliffs in Canyonlands. Both are eolian, or windblown, sand dune deposits, although the beds of ancient river systems appear to occur within the Wingate.In the Island in the Sky area of Canyonlands, we hiked across Early Jurassic rocks of the Glen Canyon Group. The Wingate, which does not outcrop in the Zion area, is around 200 million years old, older than the Navajo Sandstone by perhaps 10–15 million years or so. In Canyonlands, the Kayenta Formation is sandwiched thinly between the Wingate and the overlying Navajo Sandstone.Beneath the Wingate are the familiar Triassic mudstone and siltstone slopes and ledges of the Chinle and Moenkopi Formations. Below that are older strata and formations I have heard of but rarely encounter. In Permian times, southwest Utah was alternately submerged beneath a shallow sea or exposed as a broad, flat coastal area called a sabkha, where limestones and siltstones of the Kaibab and Toroweap Formations were deposited. Here in eastern Utah, though, Permian rocks of the Cedar Mesa Sandstone, Organ Rock Shale, and White Rim Sandstone paint a somewhat different but related picture. My simple, broad explanation is that these eastern Utah rocks were deposited in an environment that was a bit further from the edge of the supercontinent Pangaea than that found in southwest Utah. Same time, different environment. I discovered something this weekend, about the relation between rocks of the same geologic time period that are separated in space by mere hundreds of miles. Seeing the Permian rocks of Canyonlands, a light bulb went on in my brain. I had a Eureka! moment. Another piece of the geologic puzzle fit. I really must not wait another thirteen years before I get over there again. I can’t get enough of the place. Alicia is too good of a tour guide!Tour guide extraordinaire!

Content analysis:

Stratigraphic context:

Recognized stratigraphic terms [n]:	Jurassic [1] Triassic [1] Permian [3] Kayenta Formation [1] Cedar Mesa Sandstone [1] Glen Canyon Group [1] Wingate Sandstone [2] Navajo Sandstone [3] Organ Rock Shale [1] White Rim Sandstone [1]
Agenames chronostratigraphy [rating]:	Jurassic [0.95] Triassic [0.76] Permian [0.81] Mesozoic [0.96] Paleozoic [0.81] Neoarchean [0.44] Phanerozoic [0.97] Archean [0.44] Lower Jurassic [0.94] Upper Triassic [0.1] Toarcian [0.76] Pliensbachian [0.76] Sinemurian [0.72] [0.44] Precambrian [0.44]

Geographic context:

Location	Country	Latitude	Longitude
Utah	US	39.4997	-111.547
Cedar	US	37.6786	-113.06
Chinle	US	36.1505	-109.579
Eureka	US	39.9548	-112.117
Green River	US	41.515	-109.47
Mesa	US	33.417	-111.831
Sandstone	US	46.1298	-92.8644
Navajo	US	35.2855	-110.289
Canyonlands National Park	US	38.2341	-109.883
Zion National Park	US	37.3228	-113.045
Island In the Sky	PH	7.4545	125.247

Keywords:

ancient river systems, Arches National Park, broad explanation, Canyonlands, Canyonlands National Park, Cedar Mesa Sandstone, different environment, Early Jurassic rocks, eastern Utah rocks, familiar Triassic mudstone, geek’s passion, geologic puzzle fit, geologic time period, Glen Canyon Group, gorgeous early spring, Green River, Kayenta Formation, La Sal Mountains, light bulb, massive vertical cliffs, Moenkopi Formations, moonless night, Navajo Sandstone, Navajo Sandstone.Beneath, old friends, older strata, Organ Rock Shale, patient soul, Permian rocks, Permian times, Perseid meteor shower, related picture, sand dune deposits, Shafer trail, shallow sea, siltstone slopes, Sky area, Sky areaLee, Sky visitor center, southwest Utah, supercontinent Pangaea, Toroweap Formations, Tour guide extraordinaire, western distances, White Rim Sandstone, Wingate Sandstone, Wingate Sandstone forms, Zion area, Zion National Park