This is an overview pull off for the old mining town of Jerome AZ. Some of the most successful mining operations in AZ were here (and at least partially visible from GZ).
You will see a whole bunch of old rusted mining cars at this easy pull off viewpoint, and also some informative panels. Between the description below and the information panels (and of course some reasonable observation skills), you can find the answers easily!
Logging requirements
- What direction from GZ shows mine digging equipment
- There is a rock slide. Observe/Critically think:
- Do u see distinct colorization to indicate mineral presence?
- Cave-ins happen in a similar way inside mine shafts. Based on what you see here, would that be a good or bad thing for those mining the deposit? Explain
- What types of mining have left visible evidence today? Which cardinal directions from GZ show these evidences?
- (Available from signage at Little Daisy Mine State Park OR the description below) Which minerals were mined in the area?
- What geological impacts did these mines have on Jerome based on your observations from GZ
History of Jerome:
"Jerome is perched on the side of Cleopatra Hill, over rich ore deposits. In 1876, mining claims and a mill were located near the town. These claims were purchased in 1882 by United Verde Co. and the tent camp was named Jerome after Eugene Jerome, a major financier of the company. Senator William Clark of Montana purchased the company in 1883. By the mid-1920's the population had grown to almost 15,000 before it began to decline. " (signage at GZ) It was the fourth largest town in Arizona in its heyday! (Azjerome.com) "The Depression of the 1930’s slowed the mining operation and the claim went to Phelps Dodge, who holds the claim today. World War II brought increased demand for copper, but after the war, demand slowed. Dependent on the copper market, Phelps Dodge Mine closed in 1953." (AzJerome.com)
At one point, there were less than 100 inhabitants, and thus Jerome earned the title "ghost town." However, businesses have moved in and Jerome is now a bustling tourist district with over 500 inhabitants.
Geology of Jerome:
"The town owes its existence mainly to two ore bodies that formed in antiquity (many scientists state a time period about 1.75 billion years ago while others would correlate it to global tectonic events during the biblical flood epic), along a ring fault in the caldera of an undersea volcano. Tectonic plate movements, plate collisions, uplift, deposition, erosion, and other geologic processes eventually exposed the tip of one of the ore bodies and pushed the other close to the surface, both near Jerome." (Wikipedia "Jerome AZ" Introduction )
Wikipedia has an extensive section on the geology of Cleopatra Hill, which I encourage you to read. In summary: During the Proterizoic time period, Cleopatra hill was on a small sub tectonic plate. Eventually, as the plates wandered from Pangea, it was merged (and melded) to the proto-North American plate. These violent forces, in combination with cold sea water altered the minerals. Since these events were volcanic, the vents involved were rich in sulfides. The extreme heat dissolved the minerals, then when they encountered the cold sea, they fell out of solution in great heaps onto the sea floor. Later, continued tectonic plate collisions warped Cleopatra Hill upward in such as way that the two ore bodies (around two vents mentioned earlier) were folded on opposite sides of the Jerome anticline (not visible).
Geology continued (of course) burying the deposits under layers of sandstone and other sedimentary stone (think Grand Canyon). More recently, crustal stretching created a basin a range topography across northern AZ. This action shifted the two ore deposits, leaving one near the surface (the United Verde Company mined this one) and the other it shifted under some basalt to a depth of 1000 ft (330 m) (UVX ore body). This is where the UVX headframes and Jerome State Historic Park now are.
Mining in Jerome:
The Little Daisy Mine is the one visible from GZ and is the mine responsible for hauling out millions of pounds of ore from inside the ground.
Shaft mining: Visible nearby, is old shaft mining equipment. It is the "Largest wooden headframe still standing in Arizona, it was completed in 1918 to haul ore up from mine. Shaft is 1900 feet deep, concrete lined with cross tunnels every 100 feet to Edith shaft. Edith shaft headframe was completed in 1915 to haul men and supplies. A wooden structure it was torn down in 1981 and replaced with the steel version you see today, 260' to NW. (Waymarking Little Daisy Mine)
Surface mining: Surface open pit mining began later, in 1918 and continued until 1940. "The United Verde open-pit mining operation was unusual in many respects and it presented conditions not commonly found in most mining enterprises. To the best of the writer's knowledge, no other surface mine operation can compare in the variety of situations which were encountered. Whereas the development of the pit conformed generally to practices prevalent at the time, many changes and innovations were required as the operations progressed. During its twenty-two year lifetime, from 1918 to 1940, great improvements were made in the methods of drilling, blasting, loading, and hauling and, as a result, technologies first used at the United Verde open pit have contributed to the development of many modern-day surface mining methods." (UA bulletin)
"The ore at the United Verde open pit was high-grade; some sulfides contained as much as 40 percent copper, some siliceous ore
measured in at more than 200 ounces of silver a ton, and some oxide ore contained more than three ounces of gold a ton. Throughout the life of the pit operation, the ore averaged 3.47 percent copper, 2.07 ounces silver, and 0.071 ounces gold per ton. Economic operation permitted the mining of are containing as little as 1.00 percent copper, or $4.00 per ton in total value." As you can see, this was a very profitable source! (UA bulletin)
Between 1915 and 1938 almost 4 million tons of ore was extracted from the mine, producing 397,000 tons of copper, 221 tons of silver and 5½ tons of gold. Ore was brought to the surface then transported by tram and burro train, to the railhead in the valley. Later, ore was taken out underground through the Josephine tunnel, which was 1300 feet down and 2½ miles long." (Waymarking Little Daisy Mine)
The metals produced by United Verde and UVX, the other big mine in Jerome, were said to be worth more than $1 billion.
Resources:
Jerome AZ, Largest Ghosttown in America - http://azjerome.com/jerome/
Little Daisy Mine - Waymarking - http://www.waymarking.com/waymarks/WMFHEB_Little_Daisy_Mine_Jerome_Arizona
The University of Arizona - A Brief History of the United Verde Open Pit of Jerome, AZ http://repository.azgs.az.gov/sites/default/files/dlio/files/nid1269/bull_178_united_verde_open_pit_ocr.pdf
Wikipedia "Jerome" -