Showing posts with label non-metals. Show all posts
Showing posts with label non-metals. Show all posts

Thursday, September 1, 2011

Homer Spit: Birds and Boats and Coal and Things (AK2011 Day 8)

The Homer Spit, with Coal Point at the end of the spit and Coal Bay near the beginning. From MSRMaps
After leaving the little lunch spot, we passed this (faux) lighthouse indicating that we were progressing on to Homer Spit, where Alaska Route 1, the Sterling Highway, comes to an end.
View of the Kenai Mountains across Kachemak Bay.

It was still rainy as we entered the spit, and powerfully windy. Here and there, we could see signs of campers on the west beach, their tents and gear tied down and heavily weighted against the wind.
Homer Spit is a bustling tourist stop, with places to eat, places sign up for and go out on halibut charters, places to buy touristy things, along with motels, hotels, condos, and B&Bs, not to mention at least a couple scattered bars and saloons. Over the many years of visits to Homer Spit, I've stopped here or there a couple times, mostly for suitable Alaskan lunches of halibut or such, but I haven't usually spent much time on the oft crowded boardwalks.
What I like to do is go directly to the end of the road and park overlooking the beach that wraps around the tip of the spit. (Google Street View of wet, potholed parking area.)

My mom and I were the only ones venturesome enough this time to walk down to the wet and windy beach.
After a storm, or almost anytime the wind isn't blowing as hard as it was, the beach is a great place to find shells and other things. Here I've found lots of rocks, mostly graywacke, and not so many shells. There is one black lump of a rock just above my foot, which might be coal. I'll get to that after a bit.
The beach is a good place to watch the waves, and to look at boats and birds.
Birds...
...and boats...
...and lots of birds, mostly gulls.
Down near the piers, you can sometimes find starfish frolicking in the waves or hanging out on the piers themselves. I've never seen this, but have found tiny living ones washed up onshore.
After not finding any starfish, I notice the coal once again.
Coal washes up on Homer Spit from a variety of sources, including some nearby seams of sub-bituminous coal to lignite found in bluffs cut into Tertiary sediments along the north side of Kachemak Bay. In fact, the Homer area was known for its coal resources long before the town was named in 1896 for con man Homer Pennock, who unsuccessfully promoted gold mining in the area for about a year before hightailing it off to the Klondike. Homer residents still come to the beaches after storms to collect coal to burn.

I leave the coal on the beach, and my mom and I retreat hastily to a drier environment: the car. We head back up the spit.
Here's a famous saloon I've never managed to stop in!
And we say goodbye to Homer Spit, Coal Bay, and Kachemak Bay. I wonder if the low, dark bluffs on the left expose low-grade coal beds.

Friday, April 29, 2011

Yuba Dredges No. 17 and 21

I read with great interest of Andrew Alden's visit two weekends ago to the Yuba Goldfields [dead link], where he saw Yuba Gold Dredge No. 17 in operation. UPDATE (29Oct2015): Unfortunately, Andrew's original post was eliminated by about.com, but his photo, and some info, still remains.

Yuba Dredge No. 17 was built in 1917 and was rebuilt twice, in the 1930's and in 2006. During it's first operating period, it shut down in 1966; it came back into operation in 2008. (The dredge did nothing for the two years from 2006 to 2008, it took two years to rebuild it, or is one of the dates incorrect?) It was described here (USBM, 1935, p. 4) as "the world's largest gold dredge."
The Yuba Goldfields on Google Earth
I visited the Yuba Goldfields back in 1981, when I went with a company engineer or oceanographer on evaluations of placer gold deposits and submittals. I was assigned this outreach project (outreach to another part of the company) by my boss, primarily because he thought it was a waste of time, because I was one of the most junior geologists around (going into my fourth year of exploration), and because it would give me a chance to learn something new (well, at least let's hope that last was one of his motivations!). I think we went to three prospects; the Yuba Goldfields in the Hammonton mining district of Yuba County, CA, on the Yuba River was probably our first stop. The property, a large one, was then being run by Yuba-Placer Gold Company. Gold was being recovered by reworking the extensive gravel fields, and sand and gravel products of various kinds were being produced.

Yuba Dredge No. 21 was in operation when I visited, despite several online histories stating that all dredges ceased operation in 1968. Dredging operations did end in '68, with Dredge No. 21 being the last dredge to shut down, but No. 21 was refurbished or reconstructed and placed back into operation sometime in 1981, where it was in operation at least through 1988. I don't know if it operated continuously from 1981, when the price of gold was going up, through 1988 and beyond into the early nineties when the parent company of Yuba-Placer Gold Company, Yuba Westgold Inc, filed for bankruptcy, but this article states that it shut down (the second time) in 1999. It sank in 2003.

While at the Yuba Goldfields in 1981, we were given a tour of Dredge No. 21. A tour of a dredge is basically a tour of a floating mill. The dredge was huge and loud, and it had low lighting except where daylight shone through openings in the outer frameworks.

There are several nice online views of the outside of a bucket-line dredges, including this QTVR at the Oakland Museum of California, and this YouTube video of Dredge No. 17, from Andrew's post. The YouTube video shows nice stills of No. 17, and toward the end has the sound of an operating dredge, a noisy ruckus that could reportedly be heard for 20 miles around.

The following video shows the interior workings of the Sumpter Valley (Oregon) Dredge on the Powder River, after an ad that can't be skipped.

[X:]
[This video is no longer available, although the original article is here, and a few photos can be seen here Instead, you can now buy Grant's Getaways: 101 Oregon Adventures, a book, no video.]
Video about the Sumpter Valley (Oregon) Dredge from Grant's Getaways, KGW.com, NewsChannel 8, Portland.
[/:X]

I no longer have photos from my long-ago tour of Dredge No. 21, but found some interior photos of dredges scattered online here and there, listed below.

Photos of bucket-line dredges:
A Few More Links:
California - Gold, Geology & Prospecting California Gold: Hammonton (Yuba River) District, how much it produced through 1968.

Placer Gold Recovery Methods Pictures and descriptions of Dredge No. 21 on pages 23-25.

Yuba Dredges were built by Yuba Construction Company, later known as Yuba Manufacturing Company, later a subsidiary of Yuba Consolidated Goldfields. A little history of the company and its many dredges can be gleaned here through careful searching and scanning; see especially the Historical Note from pages 1-2. Numerous dredges are mentioned in the list of documents that follows.

Also see Hammonton and Marigold, a book by Robert and Ruth Criddle (2007), which can be previewed here on Google Books and here on Amazon.com).

most recently updated on 6Nov2015

Saturday, October 31, 2009

Highlights of Travel Day Three #1

I'm back to the intermittent series I started more than a week ago, which shows photos and geology from my travels to the GSA Annual Meeting - and back again, as soon as I get that far. Last you saw of this series, I had just arrived in Klamath Falls, Oregon, and was enjoying an IPA at a local pub. The morning of the third day dawned cloudy, with very nice lighting. I enjoyed the chill air, and walked around downtown KFalls while drinking coffee from a tiny styrofoam cup provided by the motel office. After several cupfuls, I finally got underway and headed north on Highway 97, which is now being called The Dalles-California Highway. I've always called Highway 97 in Oregon "The Bend Highway" - because it goes through Bend - and personally think that any highway running through Oregon should not be allowed to have the word "California" attached to it. I say this as a bred (barely) and born Oregonian.
Along the road, just barely north of town, you will come to a roadcut with some bright, white rocks (Google Maps location). I remember this roadcut from a very long time ago, when I was a young girl growing up in California (yes, the ignominy of it all). We traveled to Oregon at least yearly, often on this highway. A diatomite mine, now inactive, sits along the side of the highway just south of this roadcut - if I remember right. I didn't find an online reference to the old mine.
This is one of my favorite roadcuts. When I first drove the highway myself in 1975, I remembered the rocks from decades past. The white, diatomaceous lake sediments or mudstones of late Miocene to Pliocene age are overlain by a basalt flow (geologic map). You can see the upright columnar jointing in the flow.

Somewhere, in a box in some garage in Alaska, there might be a very old hand sample from this roadcut. Maybe.
Just around the corner to the north, Highway 97 goes into a straight stretch, pointing straight at several exposures of young-looking fault scarps belonging to the East Klamath Lake Fault Zone. The zone is seismically active. This article makes it look like there was a 1947 earthquake along or just north of the mapped zone, and this CVO page discusses the West and East Klamath Fault Zones in relation to Crater Lake and historic earthquakes. The fault can be seen in the large cinder/gravel mine to the right of the highway - which is accessible when it isn't active - and it can be seen in a very good and accessible exposure on the same hillside, just left of where the highway is pointing in the above photo.
To get to the best exposure I've seen, turn right on this paved road, then immediately turn left into the gravel ramp and old road seen in the center of the photo beyond the paved road. You can park somewhere along the old road, and then walk to the scarp.
This exposure of the fault scarp (Google Maps location) is accessible with some hiking up the steep slope. I didn't hike up this time, but have on previous occasions. I've also poked around the cinder/gravel mine, a few years back when it was closed. The fault places bedrock of basaltic cinders and possible flows against somewhat reddish older alluvium. It looked to me like younger, lighter brown talus was not offset by the fault. The fault surface is smooth, grooved, and slickensided, and compares favorably to the Genoa fault scarp south of Carson City for a great fault exposure.

I have some old non-digital photos of this Klamath Basin fault surface, and will surely scan them someday.
Fault surfaces are visible along the highway for several miles, mostly in areas where rocks are kept behind barriers and metal screens. The road is narrow, often with curves, and it cuts into a steep, talus-ridden hillside. Traffic is often incessant. There are a few small pullouts on the southbound side of the road - these are hard to stop in because they are so short. They also precipitously overhang the railroad, which is below the highway closer to the lake. I've stopped at one or two of these pullouts; they don't really provide very good access to the roadcuts.
At this pullout on the east side of Highway 97, you can look across Upper Klamath Lake and see several volcanoes. It was a bit cloudy, so I got decent photos of only two, Mount Harriman, above, and Pelican Butte, below. Mount Harriman is one of four (or more?) shield volcanoes inside the Mountain Lakes Wilderness. Pelican Butte is a shield volcano just northeast of Mount McLoughlin.

Just up the road apiece, I saw these signs, and made a sudden, unplanned side trip... to Crater Lake.

A Reference:
Priest, G. R., Hladky, F. R., and Murray, R. B., 2008, Geologic Map of the Klamath Falls area, Klamath County, Oregon: State of Oregon Dept. of Geol. and Mineral Resources, Map GMS-118.

Monday, June 23, 2008

Mining and Exploration News

Just a few summaries and links to mining and exploration stories out recently. Excuse some dorky titles. How can you tell which titles are dorky? Easy, the dorky ones are mine.


From Ron Schott's Geology Picks:
Not so Good Oil and Gas Exploration in Washington state

From Geology.com:
Surprise, surprise, there's a new gold rush in CA!
Internet Addiction - do YOU suffer from it? (Oops - not mining related unless you are reading this blog post over and over again!)

Also from Geology.com:
Geologists are needed in Australia

But in other reports (and comments), jobs aren't really available unless you KNOW SOMEONE.

Canada can't attract women into mining jobs according to this article - also from Geology News - although on my spring field trip, all the women geologists were Canadian, except for me.

I could find no reference in the above news release to open-pit mines - I guess we're on our own! Also, the news release mentioned driving the referenced new equipment through mineshafts. Mine shafts are vertical, and no underground trucks or truck drivers drive up and down through these things (shafts). The driving is done in mine tunnels or adits, and in declines or inclines. Declines are mine tunnels or adits that descend gradually as you walk into a mine (or drive - a geologist should be so lucky!); inclines are tunnels that go uphill at a very slight angle as you enter the mine, usually for drainage purposes. Also, the article speaks of the "roofs" of underground mines, a somewhat vague term that could refer to the rocks immediately overhead while underground, or possibly to surface rocks above the entire mine - I'm not really sure which, because if you are in an underground mine, the surface over your head is called the "back." And that's because when the old-timers made their tunnels, they were typically not very high, and the miners had to bend over to enter and walk through them, thus having their backs almost in contact with the "ceiling" of the mine adit.
Last but not least, lots of things have been happening in Arizona - as usual - see these articles and more at Arizona Geology:
Arizona Geology shows a neat, colorful table comparing commodity prices over the past decade, described somewhat more fully at Pitpundit Blog.