Posts tagged geology
Posts tagged geology
The second story listed on the cover of this month’s Geology issue is “The shadow of Mordor haunts Middle Earth”.
Sadly, the article is actually about Earth’s Middle Age, not the Ages of Middle Earth. Still, it is worth a read, since most of us could use some better information on the Mesoproterozoic and Neoproterozoic. After all, that’s ~ a billion years of earth history, and whatever happened then set the stage for the diversification of life in the Ediacaran and Cambrian.
I’ll accept that pumping the water out (or in) can trigger small quakes (Just look at Oklahoma). But I don’t think we can prove any linkage to larger tremors. Even if there is an earthquake in the central valley larger than magnitude 6.7 in the near future, causality will be difficult to demonstrate. How can you know if changes in the water table have sped up a quake’s occurrence when the quake is already years overdue?
This site is totally worth a look.
Trans-Alaskan Oil Pipeline
A great example of what you can save when you invest in science.
This vital lifeline transports about 17% of the domestic oil supply for the United States. At current prices, the value of oil flowing daily through the pipeline is about $25 million.
To transport oil from Prudhoe Bay on the Arctic Ocean to the ice-free port of Valdez on the Gulf of Alaska, the pipeline had to cross the Denali Fault. During the 2002 Denali Fault quake, the ground was offset beneath the pipeline, and violent shaking damaged a few of the pipeline’s supports near the fault, but the pipeline did not break.
The survival of the pipeline in the Denali Fault earthquake was the result of careful engineering to meet stringent earthquake design specifications based on geologic studies done in the early 1970’s by the U.S. Geological Survey, Woodward-Lundgren and Associates, and others in conjunction with the Alyeska Pipeline Service Company. Those studies located the Denali Fault within a 1,900-foot corridor crossing the pipeline route and estimated that the pipeline could be subjected to a magnitude 8.0 earthquake in which the ground might slip 20 feet horizontally and 5 feet vertically. These estimates proved to be remarkably accurate for the 2002 magnitude 7.9 earthquake, in which the rupture crossed the pipeline within the 1,900-foot corridor, and the fault shifted about 14 feet horizontally and 2.5 feet vertically.
To accommodate the projected fault movement and intense earthquake shaking from a magnitude 8.0 quake, the zigzagging Trans-Alaska Oil Pipeline, where it crosses the Denali Fault, is supported on Teflon shoes that are free to slide on long horizontal steel beams. Such creative engineering solutions used in the pipeline design and the studies that led to them cost only about $3 million when they were done in the 1970’s. Had the pipeline ruptured in the Denali Fault quake, the lost revenue and the cost of repair and environmental cleanup could have easily exceeded $100 million, perhaps many times.
Source: USGS Publications
Bowling Ball Beach - Schooner Gulch State Beach, California
At the edge of the Pacific Ocean, the beach at Schooner Gulch State Beach near Mendocino, looks as though its been scattered with oversized bowling balls. Almost perfectly spherical, stones like these have caused wild speculation wherever they’ve been discovered, with answers from aliens to dinosaurs, but the answer is actually simple geology.
Best observed at low tide, the so-called bowling balls are actually a geological phenomena known as “concretion”, sedimentary rock formed by a natural process wherein mineral cements bind grains of sand or stone into larger formations. These boulders are the result of millions of years of concretion and erosion, exposing the hard spheres as the mudstone of the cliffs receded around them.
Rutile Quartz cluster
I don’t know if it’s the titanium (rutile is TiO2) or the fact that rutile has an incredibly high refractive index (giving it an adamantine luster), but I really do love rutile.
Columnar basalt along the Yellowstone River, Yellowstone National Park, Wyoming
Photo by Clif Doyal -2004
From Earth Science Picture Of The Day; January 17, 2014:
Photographer and Summary Author: Ryan Miller
The photo above shows a portion of the Tongariro Alpine Crossing mountain trail on the North Island of New Zealand. This crossing stretches across the Tongariro volcanic complex on the North Island’s Central Plateau. Seen in the background at left center is Mount Ngauruhoe, a parasitic stratovolcano rising to a height of about 7,500 ft (2,290 m). In the Lord of the Rings Trilogy, Mount Ngauruhoe was featured as Mt. Doom. The crossing is approximately 12 mi (19 km) in length and normally takes about seven hours to complete. Photo taken on March 29, 2011.