Gold King Mine, Colorado: Unplugged

     On August 5, 2015, at 10:30 a.m. the Environmental Protection Agency (EPA) breached a plug or dam on toxic mine waters near the Gold King Mine 

sending over 3 million gallons (originally reported by the EPA as 1 million gallons) of arsenic and metal-rich water into Cement Creek which flows into Las Animas River ("River of Souls") in southwest Colorado.

        Stephanie Paige Ogburn's 8/6/15 article (written just a day after the spill) is one of the more balanced compilations available as it pulls together geological background, mining history, and historical background about the relationship between the EPA and the Silverton community.

       "For years, the EPA has wanted to name areas around Silverton as a Superfund site. This brings funding for cleanups. The town, in turn, has resisted fearing the label would be toxic to tourism (pun intended.)"

      The EPA was well aware that high levels of toxic materials were in long-abandoned mine debris ponds. It is most unfortunate that the spill made its way into the Animas River (here near Silverton), has now entered New Mexico and Utah, enroute to Lake Powell: 

       In addition, the naturally-occurring ferricrete ("iron concrete") deposits in the area add to high levels of metals, sulphates and other toxins. The name Cement Creek was given for a reason. There haven't been many fish in this creek for decades, perhaps over a century. The disturbance of the mine's debris waters could have happened without the EPA's heavy machinery accident. This image shows the Red and Bonita Mine south along Cement Creek which also has very high levels of toxic materials:

     The EPA did not report the incident to the community for 25 hours (bad PR and outside EPA's own 24-hour reporting window). In addition, the original 1 million gallon reported EPA number could have easily been more accurately seen at the USGS stream flow and gage height site. I pulled these two graphs yesterday showing the 8/5/15 spike of 3 million gallons (with some multiplication of cubic feet per second (cfs) times the number of seconds in the second graph):

     All of these data are available online to the public.   

    The EPA today reported toxic material including lead levels that are 12,000 times the acceptable EPA levels. Arsenic, mercury and cadmium are also extremely high. Of particular concern is the cadmium level as cadmium is readily absorbed into plant material, posing a fairly distinct short-term risk to both the plants and any animals, including humans, who consume them. (Although, I wonder about these humans below and their decision to stay in their kayaks being directly exposed to the orange sludge): 

          I would enjoy hearing your thoughts about the Gold King spill,surrounding Silverton area mines, and Superfund sites. I am particularly interested in finding out who makes the ultimate Superfund site (National Priorities List or NPL) decision. The Animas River Stakeholders Group, which includes Silverton residents, business representatives, AND the EPA, appears to have the ability to say "yeah" or "nay" to the decision about the Silverton area.

Unplugged here,

Steph

      A marvelous part of my mishpokey, Zoë (in the orange shirt [what else this week?]) is headed today to the Amhara region (colored fuchsia on the map below) of Ethiopia for her Peace Corps service. Other groups will go to Tigray, SNNP, and Oromia.

       This "USA map according to Geologists" is both amusing and fairly accurate except for 1) "nothing to see here" (I am considering the Ashfall Fossil Monument in eastern Nebraska for next week's topic) and 2) "Too hot to do field work in summer" in southern AZ as that's where we did summer field work (yes, it was pretty hot!)

Exquisite Dating Tool: Zircons as Indicators of Earlier Closing of the Land Bridge Between North and South America

          New research indicates that the connection between North and South America was created 13-15 million years ago rather than 3-5 million years as previously thought. The age of zircons was the main indicator of the much older closing age. Here's an image of a  zircon (greenish elongate diamond) in crossed nichols polarization:

           Zircons are crystals that form when magma cools. Newly-formed zircons contain some uranium, but no lead.  Therefore, any lead found in an old zircon must have originated in the radioactive decay of uranium. Thus, zircons are a favorite tool for dating in geology. (as well as dinner and a movie ;-)).

          Zircons found in streams in Colombia and Panama have dated the closing of the gap and formation of the "land bridge" at 13-15 million years.

           The biggest mystery is why animals, especially mammals like this racoon ancestor, 

Chapalmalania, 

did not make the mass movement across the land bridge until 3-5 million years ago (as seen in the fossil record). Perhaps the "land bridge" was more like a series of volcanos with shallow waters in between so it took ten million years for a solid, continuous land bridge to form. 

            This research was performed by Camilo Montes et al. This article also contains a link to terror birds (if you dare). [And a new terror bird species has just been discovered as reported on April 13, 2015.]

             Any ideas as to what was going on in the 10 million years between the possible closing of the North and South American continents and the mass mammal migration (say that 5 times fast!)?

Zirconly,

Steph