Wednesday, March 9, 2016

Caves of the San Luis Valley Colorado

Caves of the San Luis Valley Colorado





"The limestone exposures are clearly visible along the east flank of the Sangres between Music Pass and South Colony creeks. At least 11 caves occur within the limestone bedrock of the area. Of these caves, Marble Cave and White Marble Halls Cave are best known. According to Michael O’Hanlon, the caves of Marble Mountain have produced more lore and tall tales than any other localities in the Colorado Sangres. Stories of hidden Conquistador gold and skeletons in chains are associated with the caves of Marble Mountain. However, as Dodds (1992) points out, the skeletal remains were reported by Elisha P. Horn in 1869 in an old fort some distance below Marble Cave. An account from 1929, described by Dodds (1992), states that an old log-and-stone fort was discovered some thousand feet below the side of Marble Mountain." ~ Referenced below.

References
Dodds, Joanne W. 1994.  Custer County, Rosita, Silver Cliff, and Westcliffe.  Focal Plain Publishing. 42 p.
Lindsey, David A., P. A. M. Andriessen, and Bruce R. Wardlaw. 1986. "Heating, Cooling, and Uplift during Tertiary Time, Northern Sangre de Cristo Range, Colorado." Geological Society of America Bulletin. Volume 97, p. 1133-1143.
Macan, Randy.  2006.  Personal communication.
O'Hanlon, Michael. 1999. The Colorado Sangre de Cristo: A Complete Trail Guide. Third Edition. Hungry Gulch Press. Westcliffe, Colorado. 71 pages.
Parris, Loyd E. 1973. Caves of Colorado. Pruett Publishing Company, Boulder, Colorado. 247 pages.
http://www.legendsofamerica.com/co-treasures3.html
La  Caverna del Oro (The Cave of Gold)
Long before the white man ever came to the United States the legend of La Caverna del Oro,  the Cave of Gold, was passed down from generation to generation by the         Indians. When the Spanish explorers arrived in the fifteenth century, monks translated the legend and the gold was eagerly sought by the explorers. 

Caverna del Oro, 13,000 feet high upon Marble Mountain, was believed, by the Indians, to be plagued by demons. However, in 1541, three Spanish monks from  the Coronado expedition forced the Indians into slave labor to extract gold from the cave. Finally, the Indians staged an uprising against the monks and two of them were killed. However, the third monk, De la Cruz, convinced the Indians that he was able to subdue the "evil spirits” lurking underground in the mine. With the help of the slave-miner natives, vast amounts of gold were brought forth from the subterranean passages. Later, when the Indians  had served their purpose, De la Cruz and his small group of surviving Spaniards killed the Indians, loaded up their treasure on pack mules, and fled south back to Mexico.
The cave was then left unexplored until about 100 years ago, when it was found again by    Elisha Horn. Climbing on Marble Mountain, only a few miles from the town of Westcliff, Horn stumbled upon a skeleton clad in Spanish armor, with an arrow sticking out of its back. Painted on the rocks above the skeleton was a very old red cross, which can still be faintly seen to this day. Near the cross was the entrance to Caverna del Oro. In  the 1920’s, the cave was explored again by a Colorado Mountain Club  led by a U.S. Forest Ranger. The Ranger had been told by a  105-year-old Mexican woman that there was gold buried deep within the  cave. The woman said that when she was a child, she could remember journeying to the cave where miners would come out with loads of gold.
         
She claimed that within 500-700 feet of the cave entrance there was an  oaken door, which was the entrance to the rich Three Steps Mine. She explained that the treasure lay behind this set of padlocked wooden doors. The Ranger and the club members explored the many rooms and passages in the cave, climbing down as far as 500 feet into the cave,  but did not discover the wooden doors, nor any gold

 

        
          
However, they did find many other interesting items, including       a 200 year old ladder and a hammer which was made sometime in the 1600’s.       Lower down on the mountain, hidden amongst the aspen trees the club       members found the ruins of an old fort as well as many arrowheads, which       were scattered about the hillsides.
Many people have since       explored the cave and have uncovered other old items including a windlass       (rope and bucket), a clay jug and a shovel left by earlier explorers or       miners. In addition, one group found a human skeleton chained by the neck       to a wall deep down in the cave.
Nevertheless, no gold has       ever been found (or at least, none that anyone is talking about.) Some people think that the entrance by the cross might have been an escape       route, rather than the true way in, and the "real” entry to the cave lies       hidden lower down on the mountainside.  Regarding the mystery of the       wooden door, behind which lies the treasure, some theorize that the door       has since been hidden by a rockslide.
La Caverna del Oro sits at 13,000 feet on       Marble Mountain, just over Music Pass to the northeast of the Great Sand       Dunes

Tuesday, March 8, 2016

Regional Geology of The San Louis Valley Colorado

The Geology of the San Louis Valley.

Located in the south central region of Colorado, the San Louis valley is the highest alpine valley on earth. Bounded by Poncha Pass on the North, the Sangre de Cristo and Culebra Ranges  on the East, the Uncompahgre and San Juan Ranges to the West and the Rio Grande Valley to the South.

This short paper is not intended to be exhaustive as there are many fine works by others (ie. DeVoto, Epis, F. Meissner, McCaplin, Tweto, Gries, Keller and others). This is introductory work for my own knowledge.

Sangre de Cristo Range - (Meissner, 2016)
It is the Rio Grande Rift and the associated Rio Grande River that describes the geomorphology of the region.

References and Cites

Thursday, March 3, 2016

Introduction to Paleoplacer Deposits



Paleoplacers

By Michael W. Meissner 

#MichaelwMeissner #Michael W Meissner #Michael William Meissner #Geologist #michaelwmeissner.com
Definitions

Placer Deposit Defined. 

  According to Wikipedia placer deposit defined as:

·         In geology, a placer deposit or placer is an accumulation of valuable minerals formed by gravity separation during sedimentary processes. The name is from the Spanish word placer, meaning "alluvial sand". Placer mining is an important source of gold, and was the main technique used in the early years of many gold rushes, including the California Gold Rush. Types of placer deposits include alluvium, eluvium, beach placers, and paleoplacers.
·         Placer materials must be both dense and resistant to weathering processes. To accumulate in placers, mineral particles must be significantly denser than quartz (whose specific gravity is 2.65), as quartz is usually the largest component of sand or gravel. Placer environments typically contain black sand, a conspicuous shiny black mixture of iron oxides, mostly magnetite with variable amounts of ilmenite and hematite. Valuable mineral components often occurring with black sands are monazite, rutile, zircon, chromite, wolframite, and cassiterite. (Plazak, Meissner, Trafford09, & Tide Rolls, 2010)
 

Etymology of Paleoplacer;  Paleo + Placer:


The word placer derives from the Spanish placer, meaning shoal or alluvial/sand deposit, from Catalan placer, (shoal), from plassa, (place) from Medieval Latin placea (place) the origin word for "place" and "plaza" in English.[2] The word in Spanish is thus ultimately derived from placea and refers directly to an alluvial or glacial deposit of sand or gravel. (Lotje, Smith, Greer, Sactor, & and Others, 2013)
  • Placer
Syllabification: plac·er
noun
[often as modifier]
A deposit of sand or gravel in the bed of a river or lake, containing particles of valuable minerals:placer gold deposits
Origin: Early 19th century: from Latin American Spanish, literally 'deposit, shoal'; related to placel 'sandbank', from plaza 'a place’
(Placer, 2016)

  • Paleo
Syllabification: paleo-
 (British palaeo-)
Older or ancient, especially relating to the geological past: Paleolithic paleomagnetism
Origin:  From Greek palaios 'ancient'.
(Dictionaries, 2016)

Economics and Importance of Placer Deposits

Mineral Mined from Placer Deposits
·  Diamonds
·  Titanium, from the minerals ilmenite and rutile
·  Gold
·  Rare earth elements, from the mineral monazite
·  Garnet
·  Ruby
·  Zirconium, from the mineral zircon
·  Iron, from ironsands containing high concentrations of magnetite
·  Sapphire
Other Industrial Minerals: Gravel, Boulders, Sand, Marble
·  Platinum group metals
·  Thorium, from the mineral monazite
Bauxite (Aluminum)







Types of Paleoplacers and Placers

  • To understand the types of Paleoplacers one must also understand Placers.
  • Eluvium or Residual
  • Alluvial
  • Beach
  • Glacial
  • Aeolian
Eluvium or Residual
In geology, eluvium, eluvial, or alluvial deposits are those geological deposits and soils that are derived by in situ weathering or weathering plus gravitational movement or accumulation. (Smith & Altenman, 2006)

Eluvial placers form on hill slopes from weathered deposits. They are not acted on by streams but by rainfall and wind, which carry away the light materials; thus they may be considered intermediate in the formation of stream placers. Examples include the earlier worked gold deposits of Australia and the cassiterite placers of Malaysia.  (Placer Deposits, 2016)

Residual deposits are more common where there has been weathering on rocks and where there hasn’t been water. They are deposits which have not been washed away yet or been moved. The residual usually lies at the site of the lode. This type of deposit undergoes rock weathering.

Alluvial
Alluvial or eluvial deposits sometimes have the largest gold deposit and are very common. This deposit is created when a force of nature moves or washes the gold away, but it doesn’t go into a stream bed. It contains pieces of ore that have been washed away from the lode. Alluvial deposits are the most common type of placer gold. This type of deposit occurs mostly in valleys. (Lotje, Smith, Greer, Sactor, & and Others, 2013)

Stream placers, by far the most important, have yielded the most placer gold, cassiterite, platinum, and gemstones. Primitive mining probably began with such deposits, and their ease of mining and sometime great richness have made them the cause of some of the world’s greatest gold and diamond “rushes.” Stream placers depend on swiftly flowing water for their concentration. Because the ability to transport solid material varies approximately as the square of the velocity, the flow rate plays an important part; thus, where the velocity decreases, heavy minerals are deposited much more quickly than the light ones. Examples of stream placers include the rich gold deposits of Alaska and the Klondike, the platinum placers of the Urals, the tin (cassiterite) deposits of Malaysia, Thailand, and Indonesia, and the diamond placers of Congo (Kinshasa) and Angola.  (Placer Deposits, 2016)

Bench
Bench deposits are created when gold reaches a stream bed. Gold accumulations in an old stream bed that are high are called bench deposits. They can be found on higher slopes that drain into valleys. Dry stream beds (benches) can be situated far from other water sources and can sometimes be found on mountain tops. Today, many miners focus their activities on bench deposits.

Beach
Beach placers form on seashores where wave action and shore currents shift materials, the lighter more rapidly than the heavier, thus concentrating them. Among the examples of beach placers are the gold deposits of Nome, Alaska; the zircon sands of Brazil and Australia; the black sands (magnetite) of Oregon and California; and the diamond-bearing marine gravels of Namaqualand, South Africa. (Placer Deposits, 2016)

(Laznicka, 2010)


Glacial
The overall quantity of the gold left behind is generally much less than you would expect to find in the western United States. Although much of the deposits that were left behind were likely very rich, they were distributed so widely across the landscape that very few areas got appreciable amounts of gold in any one area. There are a few exceptions however, where significant deposits have been recovered.

Most glacial gold is extremely fine textured. The occasional “picker” and nugget can sometimes be found, but most gold prospectors in the Midwest have found that by using techniques that are specifically designed for fine gold recovery will result in the highest yield.

Pleistocene glacial and related fluvial sediments of the Cariboo Mining District in central British Columbia, Canada.  (Nicholas Eyles, 1989)

Glacial placers, that overlie the fluvial placers, occur within lodgment till complexes deposited below the retreating ice sheet, the basal portions of lodgment tills are commonly enriched in gold as a result of incorporation from older gravels. Subglacial meltwaters created a highly effective sluicing system and left lucrative pay zones along meltwater-cut channels on bedrock benches, within intraformational gravels in lodgment till and within “lee-side” deposits down-ice of bedrock highs. “Lee-side” deposits are essentially water-worked talus slopes that accumulated in subglacial cavities. Finally, postglacial “wandering gravel-bed rivers” have repeatedly reworked older placers resulting in rich pay zones at the base of extensive bar platform deposits.  (Nicholas Eyles, 1989)

Similar sedimentological controls on gold distribution can be identified in other glacial placers of late Cenozoic and Paleozoic age in North America, southern Africa and Australia. A distinction is drawn between these placers, all characterized by coarse-grained, nuggety gold, and the more well-known Precambrian and Paleozoic placers where finely-comminuted gold is dispersed through large thicknesses of rock. Episodes of glaciation typically occur after long periods of tropical and subtropical weathering when supergene processes were active and glaciers were able to remove and concentrate coarse gold. In contrast, gold in non-glacial placers of Precambrian and Paleozoic age has been through many cycles of erosion and transport and coarse gold is uncommon. (Nicholas Eyles, 1989)

Aeolian also spelled eolian or æolian

Eolian placers may form in arid areas where wind, not water, acts as the concentrating agent, removing fine particles of the lighter dross. The gold deposits of some parts of the Australian desert are examples.  (Placer Deposits, 2016)
Windblown deposits of mineral-rich dust and silt is called loess.  The term comes from the German word Loss and from the Alemannic  word losch which means "loose".

A sedimentary rock formed from sand deposits is called a 'Sandstone' or generically a 'Psammite'
Aeolian processes, also spelled eolian or æolian, pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth (or other planets). Winds may erode, transport, and deposit materials and are effective agents in regions with sparse vegetation, a lack of soil moisture and a large supply of unconsolidated sediments. Although water is a much more powerful eroding force than wind, aeolian processes are important in arid environments such as deserts.
The term is derived from the name of the Greek god Aeolus, the keeper of the winds.
Paleoplacer Types:
Witwatersrand-Type:

Type Locations of Placers and Paleoplacers


Placers Type Locations











Paleoplacer Type Locations

Rand District




Sierra Nevada




Huronian Supergroup of Ontario





Understanding the Gold Systems as a Best Practice

Bibliography


Dictionaries, O. (Ed.). (2016, 2 28). Paleo. Retrieved 2 28, 2016, from Oxford Dictionaries: http://www.oxforddictionaries.com/us/definition/american_english/paleo-
Laznicka, P. (2010). Giant Metallic Deposits: Future Sources of Industrial Metals (Second ed.). West Lakes South Australia, Australia: Springer Heidenlberg Dordrecht. Retrieved 2 28, 2016, from https://books.google.com/books?id=1tWllDxMkEYC&pg=PA557&lpg=PA557&dq=type+localities+for+paleoplacers&source=bl&ots=ia5FRNZ9Sm&sig=meY5hcva3JABUGfCyO83yDI1vzs&hl=en&sa=X&ved=0ahUKEwiI57vzo53LAhUk4qYKHcO5AgEQ6AEIUTAI#v=onepage&q=type%20localities%20for%20p
Lotje, Smith, Greer, Sactor, & and Others. (2013, 5 3). Wikipedia. Retrieved from Placer Mining: https://en.wikipedia.org/wiki/Placer_mining
Nicholas Eyles, S. P. (1989). Sedimentological controls on gold in a late Pleistocene glacial placer deposit, Cariboo Mining District, British Columbia, Canada. (E. B.V., Producer, & Elsevier B.V.) Retrieved 2 28, 2016, from Science Direct: http://www.sciencedirect.com/science/article/pii/0037073889900055
Placer. (2016, 2 28). Retrieved from Oxford Dictionaries: http://www.oxforddictionaries.com/us/definition/american_english/placer
Placer Deposits. (2016, 2 29). Retrieved 2 29, 2016, from Encyclopedia Britannica: http://www.britannica.com/science/placer-deposit
Plazak, Meissner, M. W., Trafford09, & Tide Rolls. (2010, December 4). Placer Deposits. (Plazic, Editor) Retrieved April 21, 2015, from Wikipediat: https://en.wikipedia.org/wiki/Placer_deposit
Smith, & Altenman, P. a. (2006, April 19). Eluvium. (Wikipedia.org) Retrieved 2 29, 2016, from Wikipedia: https://en.wikipedia.org/wiki/Eluvium