Utah Geological Survey

POTD September 20, 2013: Snow Canyon State Park, Washington County, Utah

Snow Canyon State Park,
Washington County, Utah
Photographer: Tyler Knudsen

About 27,000 years ago, lava flowed on top of the Navajo Sandstone, forming black “ropey” basalt in Snow Canyon State Park, Washington County.

Utah is peppered with volcanoes and other signs of the hot molten rock (magma) that forms within the crust beneath us. Magma, less dense than the surrounding solid rock, rises where it can and intrudes into adjacent rock to form laccoliths, batholiths, dikes, and sills upon cooling. It can also extrude onto the surface as lava, sometimes explosively ejecting lava fragments and ash. The resulting igneous rocks can vary widely in appearance.

Utah Geological Survey

Geologic Map of the Yellowjacket Canyon Quadrangle, Kane County, Utah, and Mohave County, Arizona

By: Janice M. Hayden

The Yellowjacket Canyon 7.5′ quadrangle is divided north-south by the Sevier fault zone with the lower Navajo Sandstone and older rocks creating the Vermilion Cliffs step of the Grand Staircase on the up-thrown block to the east, and the upper Navajo Sandstone and younger rocks creating the White Cliffs step of the Grand Staircase on the down-dropped block to the west. Exposed strata range from the Triassic Petrified Forest Member of the Chinle Formation to the Jurassic Co-op Creek Limestone Member of the Carmel Formation. Eoloian sand dunes, including those of Coral Pink Sand Dunes State Park, stretch northeast to southwest across the map area.

This CD contains geographic information system (GIS) files in ESRI file geodatabase and shapefile formats. Also included are two plates-the geologic map at 1:24,000 and the explanation sheet-both in PDF format. The latest version of Adobe Reader is required to view the PDF files. Specialized GIS software is required to use the GIS files.

M-256DM……….. $24.95

GET IT HERE

 

 

Utah Geological Survey

POTD September 19, 2013: St. George basin, Washington County, Utah

St. George basin, Washington County, Utah
Photographer: Robert F. Biek

Beyond the 350,000-year-old (Pleistocene-aged) Sullivans Knoll (Volcano Mountain) cinder cone near the town of Hurricane, the snow-covered Pine Valley Mountains are the eroded remnants of one of the world’s largest laccoliths, a shallow, mushroom-shaped igneous intrusion that formed about 20 million years ago. The red,  Jurassic-aged Navajo  Sandstone in the middle ground is on the northwest-tilted limb of a large upwarp called the Virgin anticline.

Utah Geological Survey

POTD September 18, 2013: House Range, Millard County, Utah

House Range, Millard County, Utah.
Photographer: Michael Vanden Berg

The Notch Peak quartz monzonite (foreground) was magma during Jurassic times and intruded into Cambrian limestone and dolomite hundreds of millions of years after the Cambrian rock was deposited as sediment in tropical seas.

 

Utah Geological Survey

Fossils discovered at St. George construction site

fox13now.com

Paleontologists in St. George are sifting through thousands of fossils, all recovered from the construction site of the Southern Parkway. And some may point to the discovery of a new dinosaur species.

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Utah Geological Survey

Video: Flash flooding in Natural Bridges

sltrib.com

A series of videos shows the muddy violence that took over slickrock country when flash floods hit Natural Bridges National Monument this weekend.
Filmed on Saturday and posted to Youtube by user asloss7, the videos show rivers raging through the usually-peaceful Armstrong and Tuwa canyons.

WATCH IT HERE

 

 

Utah Geological Survey

POTD September 17, 2013: Silver Island Mountains, Tooele County, Utah

Silver Island Mountains, Tooele County, Utah
Photographer: Ken Krahulec

Limestone has been enriched with silver and lead from  mineral-rich fluids driven by underlying plutons in the Silver Island Mountains, Tooele County.

A pluton is a body of magma that cools and crystallizes deep  within Earth’s crust, and is typically granitic in composition. Utah’s wealth of rich ore deposits is in large part due to the plutonic process. During pluton emplacement, minerals form in surrounding rock. Limestone and dolomite in particular are prime host rocks for mineralization and concentrations of ore.

Utah Geological Survey
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Discoveries emerging from fossils found at Southern Parkway Project excavation sites

stgeorgeutah.com

Four new paleontological sites were discovered during the Southern Parkway project in Washington County, and 10 previously known localities were surveyed for additional paleontological resources. Paleontologist Andrew Milner shares his findings, some of which may be entirely new discoveries to science.

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Utah Geological Survey

POTD September 16, 2013: Granite Peak, Beaver County, Utah

Granite Peak, Beaver County, Utah
Photographer: Tyler Knudsen

Spectacular granite crags loom high above Ranch Canyon in the Mineral Mountains. An immense aggregation of smaller intrusions, the 18 million year- old  (Miocene-aged) Mineral Mountains batholith (large body of intrusive igneous rock) is the largest exposed batholith in Utah.

Utah Geological Survey

POTD September 13, 2013: Zion National Park, Washington County, Utah

Zion National Park, Washington
County, Utah
Photographer: Tyler Knudsen

Utah showcases a multitude of canyons as varied as its high mountains and dry deserts. Ranging from V- and U-shaped valleys at the edge of mountains to deep and narrow slot canyons in the south, the shapes result from types of erosion and factors such as precipitation amount and rock type. Erosion can be from powerful rivers and glaciers, forceful flash floods, or winds adding a sculpting touch.

A unique tunnel-like passage sculpted by stream water is called the Subway section in this slot canyon in Zion National Park, Washington
County.