To Log This EarthCache include:
1. The name of this EarthCache on the first line.
2. The number of people in your group.
3. What is the depth to the bottom of the hole at Honeycomb Cavern? A) 5-10 feet; B) 15-20 feet; C) >50 feet
4. The marble here is mostly composed of the mineral: A) dolomite; B) calcite.
5. The number of feet of sediment is likely: A) less than 3 feet; B) 3-10 feet; C) more than 10 feet.
6. The discharge of San Diego ditch water is closest to: A) 0.1 cfs; B) 1 cfs; C) 10 cfs; D) 100 cfs.
7. Which Big Ideas (1-9) are connected (list)?
8. Which GeoPrinciples are relevant (list)?
9. Include a photo or 2 if you're so inclined (optional).
===============================================================================
GEOLOGY OF COLUMBIA MARBLE
Everywhere you look in the Columbia area there seems to be marble – that whitish rock that kids climb on in Columbia State Historic Park. This EarthCache explains: 1) the origin and geologic history of the marble (also called limestone by some); 2) three locations to observe the marble on the campus of Columbia College (a community college near old town Columbia); and 3) some uses of marble along with interesting features. The EarthCache has three parts and you will have to walk/hike to 3 different outcrops at the college to complete it. The rocks you see here are part of the Calaveras Complex (see Figure 1), a subduction zone complex, composed of mostly argillite (hardened, or lithified, slightly metamorphosed mud and clay), quartzite (quartz sand grains fused together), and chert/metachert (hard, usually dark, microcrystalline, silica-rich rock). However, it also contains lesser amounts of metamorphic schist, phyllite, slate, and lenses of recrystalized limestone and dolomite metamorphosed to marble (see Figure 1). There are also minor marine metasedimentary and metavolcanic rocks present.
Figure 1: Map of the Calaveras Complex marble and EarthCache location at Columbia College. The marble (shown in blue) stretches almost continuously from Pioneer (northeast of Jackson) in Amador County, to southeast of Sonora and Jamestown, in Tuolumne County.
Most of the Calaveras Complex formed offshore in warmer, relatively deeper water as evidenced by the paucity, or lack, of coarse-grained rocks. Enormous amounts of mud and clay were eroded over time and deposited along the continental slope into a subduction zone trench. At least one volcanic island, fringed by a reef deposit, collided with the coastline and was tectonically dragged down into the trench, then accreted (or welded) onto the continent. Layers of mud, silt, sand, plus the island arc, all formed an accretionary wedge along the edge of the North American continent during the Jurassic period, approximately 175-150 million years ago.
The Calaveras Complex body of marble, the largest of its kind in the Sierra Nevada, forms a long, thin, fairly continuous belt, stretching from the town of Volcano, in Amador County, to south of Sonora, in Tuolumne County, over 65 miles in length and up to 7 or 8 miles wide (see Figure 1). The marble is mined for various uses in Columbia by Blue Mountain Minerals and their geologist, Carey Haughy, found fossils identified as Amphipora, a rock-building, reef-forming organism, called a stromatoporoid (see Figure 2). They were formerly thought to be corals, but are now considered to be sponges, more specifically, sclerosponges that have soft bodies covering a hard skeleton made of calcium carbonate - either calcite or aragonite. Amphipora could live 500-1,000 years and their dense skeletons were deposited in a layered, chronological pattern, which makes them look like reef corals and they are therefore called coralline sponges. The reef structure likely formed during Devonian time (~416 to 358 million years ago) in a shallow, warm sea. The original limestone has largely been altered to dolomite and calcite marble in the region.
Figure 2: Amphipora fossils found at the Blue Mountain Minerals carbonate mine in Columbia, CA. The upper right specimen likely contains graphite-rich calcite, thus the darker gray color of the matrix. The Amphipora fossils are made of calcite - the white mineral observed. The other specimen on the lower left shows the Amphipora structure replaced by silica (did not scratch with a knife).
Following deposition of the reef, the rock was then metamorphosed, uplifted, faulted, and fractured. The Calaveras Complex contains numerous caves and caverns, likely formed during the last ice age. Abundant, slightly acidic groundwater percolated through the soil into the marble bedrock, through fractures (called joints) caused by the faulting and uplift. Groundwater action has widened joints, as the rock dissolved, into caves, then into the cavern systems seen today. Historian Theordore Hittell wrote in 1898 that it was reported that one underground cavern had an opening in Columbia with an outlet in Jamestown, 8 miles away:
“Gold Spring was a mile or two northwest, and Springfield three or four miles south, of Columbia; and, like Shaw’s Flat and Sawmill Flat, they were both on the limestone belt. Both got their names from the remarkable springs, supposed to be the outlets of subterranean streams flowing through limestone fissures. One of these streams was supposed to run under Knapp’s ranch east of Columbia. There was a hole in the limestone there, down which adventurers climbed for a distance of one hundred and fifty feet and were then let down with ropes one hundred feet further when they came to a stream of clear water four feet wide and twelve feet deep. There were several other holes of this kind near Columbia, one of which led into a subterranean channel that had its outlet below Jamestown about eight miles distant.” (Hittell, 1898, pg. 123).
Andrew Alden, geologist and author, identified the carbonate rock surface in Columbia as a karrenfeld, which is “a limestone or marble surface with large fissures (karren) dissolved into it. He then described this feature:
“South of Columbia near Shaws Flat, a particularly rocky area of the karrenfeld displays a planar surface of clints and grikes. The terminology of karst [an irregular limestone or marble region with sinkholes, underground streams, and caverns] is intricate, reflecting the great variety of forms produced by the interaction of water and lime rocks. Where a flat limerock surface is attacked by water, solution grooves may form along bedding planes or fractures (joints). The surfaces between the grooves are clints, and the grooves are grikes (or grykes). Generally a clint-and-grike karrenfeld is a fairly regular grid. At Columbia the surface is much more irregular, with wider grooves, and is better classified as a crevice karst. In any event, this wide, rugged hard-rock surface acted for millions of years as the riffles in the bed of an enormous sluicebox. Large deposits of gold-bearing gravel traveled over the Columbia area and heavy nuggets were left behind, in seemingly every hollow. The first miners pulled fist-sized nuggets from the ground here starting in 1850, and thousands of gold-seekers followed. Columbia had the richest gold placers ever discovered. Some $500 million worth of gold (at today's prices (~$280/oz c. 2005, or $2.68 billion in 2011 @ ~$1,500/oz, [or ~$2.27 billion in 2017 @ ~$1,270/oz])) was dug out by hand in less than 20 years. For a time it was the second-largest city in California. Now all that's left is a state historic park, a marble quarry north of town, and the ancient karrenfeld.”
Columbia’s karrenfeld karst surface was one of the richest gold districts in all of the Sierra Nevada. The marble was able to act as a natural riffle system to trap placer gold being carried over the surface by a Tertiary river. According to Lindren (1911):
“The Columbia basin is a flat, open valley about 2 miles in diameter, at an elevation of about 2,100 feet, just to the east of and 1,000 feet above the canyon of the Stanislaus. …A broad belt of crystalline limestone occupies the center of the Columbia basin from north to south. On each side of the belt are ridges of the Calaveras formation; they seem to have been particularly resistant on the east of Yankee Hill [northeast of where Columbia College is today]. The valley lies between two areas of granodiorite intrusive into the slates and in this separating strip, which is a few miles wide, a great number of narrow but extremely rich “pocket veins” have been formed. The slow degradation of this area during prevolcanic time concentrated the coarse gold to an extraordinary degree in the flat central basin; deep potholes corroded in the limestone proved to exceptionally effective gold riffles.”
Hittell (1898) further describes some of the gold nuggets found in the Columbia area:
“In 1858 a nugget, weighing over fifty pounds and containing over eighty-five hundred dollars worth of gold, was found by a Mr. Strain about half a mile east of Columbia in Tuolumne county on a trail leading up the slope of a hill, where it had been repeatedly passed by others." "…and in 1859 a Mr. Virgin found one worth about seven thousand dollars at Gold Hill near Columbia.” (Hittell, 1898, pg. 143).
Today, the marble is mined and crushed at a quarry just north of Columbia (by Blue Mountain Minerals) for raw materials used in various industrial purposes. These primarily include: 1) agriculture (soil amendment/animal feed); 2) building and construction (glass, concrete, etc.); and 3) energy and environmental applications (neutralizing acid biomass fuel emissions, remediation of acid soils, etc.). On average, approximately 80 dry bulk tanker trucks leave the mine each day to Central Valley destinations.
To complete this part of the EarthCache you will need to hike to the GPS coordinates at 3 separate locations on the college campus. Use common sense as you navigate to each location. Beware of poison oak on campus.
Stage 1 Honeycomb Cavern GPS Coordinates (Latitude: 38.034246; Longitude: -120.386539): You are standing at the sealed entrance to Honeycomb Cavern, mapped by Ralph Squire, a local spelunker and cave enthusiast, in the early 1970’s. His map of the cavern shows it to be at least 190 feet long with a total vertical elevation change in the system of approximately 60 feet. Speleothems were observed and identified and one room in the cavern was large enough to stand up in. Columbia College administrators were notified of potential hazards in the cave (some pathways were extremely tight to navigate through), so they had the entrance sealed off for safety reasons. Once you have located the opening, estimate the approximate depth to the bottom of the hole. To the southwest of the opening there is a small sinkhole that first began to form in the mid-1990’s. It is approximately 3 feet deep and seems to have stabilized. The soil around the marble boulder is slowly lowering and may collapse into the cavern below at some point in time, but for now, things seem to have reached an equilibrium. Use common sense and be safe as you observe the sinkhole from a distance.
Stage 2 The Arboretum GPS Coordinates (Latitude: 38.033272; Longitude: -120.389259): Take the stairs, near the Toyon building, down to this location, called the Arboretum (though, technically, it is an interpretive trail through a mined area where trees now grow). Miners in the 1850’s removed sediment laden with gold from this marble karst surface, likely flushing it out through a tunnel once located at the south end of the Arboretum. They were mining auriferous (gold-bearing) gravels for gold nuggets deposited here by a Tertiary stream. Now observe the rock outcrop at the GPS location. Note the texture including the grain size of the minerals in the rock. This is marble that formed from rock-building organisms, similar to coral that lived in a shallow, warm sea, off of a volcanic island (similar to Hawaii today). The rock has been recrystallized from tectonic forces, so the fossils are no longer visible. Dolomite and calcite are the 2 primary carbonate minerals that make up the marble in the area. Dolomite is generally whiter in color and the calcite looks grayer and is more translucent. Examine the outcrop here. Based on color, is there more dolomite in the rock, or more calcite?
A ditch and flume system that intercepted the Stanislaus River at higher elevations conveyed water to Columbia for mining purposes (part of the ditch system is still intact and you will use it for Stage 3). Assuming the marble here was covered with sediment, estimate how much the ground surface was lowered if this location was once fully buried under gravel before miners arrived.
Stage 3 San Diego Ditch GPS Coordinates (Latitude: 38.029432; Longitude: -120.387860): At this location you will estimate the volume of water flowing through the San Diego Ditch, called the “discharge”. The Tuolumne Utilities District manages the ditch system for water supply to people and businesses in Tuolumne County. Their infrastructure can be seen just downstream of this location with the white flume and utility box nearby. This system measures the discharge of the ditch at any given time. During the mining era, miners were charged for the water they used by the Tuolumne County Water Company. The unit water was measured in was called a “miner’s inch”, which is approximately 1.5 cubic feet of water per minute; the miner’s inch is still used today by local water companies. Find the footbridge over the ditch near the GPS coordinates. To measure the discharge you will need to estimate the average width of the ditch, the average depth, and the velocity of the water. Be sure to estimate each value using units in FEET – how many feet wide and deep, then estimate how many feet per second the water here is flowing. To estimate the velocity, find a stick nearby and drop it into the ditch. Then estimate how many feet it floats in 10 seconds. Divide the number of feet obtained by 10 (for example, 18 feet traveled in 10 seconds = 1.8 feet per second) to obtain the water velocity. Multiply the width times the depth times the velocity to obtain the discharge, measured in cubic feet per second (cfs). How many cfs did you measure?
Geoscientists have to be skilled in several different areas. They need to be somewhat proficient in: math, physics, chemistry, biology, surveying, geospatial technologies (GPS, GIS, remote sensing, and webmapping), lab technologies (microscopes, spectrometers, etc.), computer use, and more. Career opportunities in the earth sciences include: geologist, hydrologist, mapping/surveying and geospatial technologist, watershed analyst, mineralogist/mining engineer, petroleum geologist, environmental scientist, natural resources scientist, and more. If you are interested in learning more, take a course at your local community college to get started.
===============================================================================
EARTH SCIENCE BIG IDEAS
The Earth Science education community put together 9 “Big Ideas” for the Earth Science Literacy Initiative (ESLI), shown below. Their purpose was to highlight the main concepts and ideas a person should understand to be literate in the earth sciences:
An Earth-science-literate person:
• understands the fundamental concepts of Earth’s many systems
• knows how to find and assess scientifically credible information about Earth
• communicates about Earth science in a meaningful way
• is able to make informed and responsible decisions regarding Earth and its resources
Which of these Big Ideas below do you think are most relevant to this EarthCache?
Earth Science Literacy Project:
- Big Idea 1: Earth scientists use repeatable observations and testable ideas to understand and explain our planet.
- Big Idea 2: Earth is 4.6 billion years old.
- Big Idea 3: Earth is a complex system of interacting rock, water, air, and life.
- Big Idea 4: Earth is continuously changing.
- Big Idea 5: Earth is the water planet.
- Big Idea 6: Life evolves on a dynamic Earth and continuously modifies Earth.
- Big Idea 7: Humans depend on Earth for resources.
- Big Idea 8: Natural Hazards pose risks to humans.
- Big Idea 9: Humans significantly alter the Earth.
For more details see: Earth Science Literacy Initiative
===============================================================================
GEOPRINCIPLES
There are several fundamental principles, developed over time, that guide geological reasoning and critical thinking, listed below. Read each short description, then use your best judgement to determine which principle, or principles, best relate to this EarthCache.
7 Principles in Geology:
- Superposition – the oldest strata are at the bottom of the sequence
- Original Horizontality - layers of sediment are originally deposited horizontally
- Lateral Continuity - layers of sediment initially extend laterally in all directions
- Faunal Succession - fossils succeed each other vertically in a specific, reliable order that can be identified over wide horizontal distances
- Law of Intrusive Relationships - the geologic feature which cuts another is the younger of the two features
- Uniformitarianism - the assumption that the same natural laws and processes that operate in the universe now have always operated in the universe in the past and apply everywhere in the universe
- Catastrophism - the theory that the Earth has been affected in the past by sudden, short-lived, violent events, possibly worldwide in scope
===============================================================================
LOGISTICS AND SAFETY
In order to log this EarthCache you will have to park in the student parking lot at Columbia College. On weekends the parking is free. During school hours you will need to purchase a parking pass for a small fee. After parking, walk to each stage. Campus Security is available 24 hours a day, 7 days a week if you need any assistance. The Security office phone number is 209.588.6170. The campus is situated on ~275 acres and it can be easy to get lost on parts! Be repsectful of students and staff and follow any safety directions on signage as you enter campus.
Visitors to this site should plan ahead and prepare by:
• Knowing the regulations and special concerns for the area you are planning to visit (obeying laws that prohibit collection or destruction of artifacts);
• Carrying a map and a GPS unit and/or compass;
• Staying on existing roads and trails (no need to go off trail for any measurements at this site);
• Staying away from any/all mine shafts and adits;
• Planning for extreme weather, hazards, and emergencies;
• Being aware that cell phones DO NOT usually work in the rural areas away from the major highways;
• Leaving your travel plans with a responsible party, including the date and time of your return;
• Being aware of any natural hazards associated with the region (e.g. mountain lions and bears (they have been sighted on campus!), poison oak, rattlesnakes, mosquitoes, cliffs/steep slopes, etc., etc);
• Carrying a full-size spare tire, extra food, water, and warm clothing;
• Following the “Tread Lightly" and "Leave No Trace” philosophy.
===============================================================================
To Log This EarthCache include:
1. The name of this EarthCache on the first line.
2. The number of people in your group.
3. What is the depth to the bottom of the hole at Honeycomb Cavern? A) 5-10 feet; B) 15-20 feet; C) >50 feet
4. The marble here is mostly composed of the mineral: A) dolomite; B) calcite.
5. The number of feet of sediment is likely: A) less than 3 feet; B) 3-10 feet; C) more than 10 feet.
6. The discharge of San Diego ditch water is closest to: A) 0.1 cfs; B) 1 cfs; C) 10 cfs; D) 100 cfs.
7. Which Big Ideas (1-9) are connected (list)?
8. Which GeoPrinciples are relevant (list)?
9. Include a photo or 2 if you're so inclined (optional).
Note: In order to manage email volume, you may assume your responses are accurate if you do not get an email after logging this EarthCache. If a response is grossly inaccurate, you will not receive credit for the cache.
===============================================================================
Note: For a brief summary of the geologic history of the Central Sierra, see this EarthCache:
Dragoon Gulch EarthCache
===============================================================================
REFERENCES
1. Alden, A., 2011, Karrenfeld of Columbia, California, retrieved June 11, 2017, from http://slideplayer.com/slide/6952204/.
2. Busby, Cathy J., Andrews, G.D.M., Koerner, A.K., Brown, S.R., Melosh, B.L., and Hagan, J.C., 2016, “Progressive derangement of ancient (Mesozoic) east-west Nevadaplano paleochannels into modern (Miocene–Holocene) north-northwest trends in the Walker Lane Belt, central Sierra Nevada”, Geosphere 12, p. 135-175, 2016, http://www.geosphere.gsapubs.org.
3. Busby, Cathy J., Koerner, Alice, Hagan, Jeanette, and Andrews, Graham, 2012, “Sierra Crest graben: a Miocene Walker Lane Pull-apart in the Ancestral Cascades Arc at Sonora Pass”, in, N. Hughes and Garry Hayes (eds), “Geological Excursions, Sonora Pass Region of the Sierra Nevada”, Far Western Section, National Association of Geoscience Teachers field guide, p. 8-36.
4. Earth Science Literacy Initiative (ESLI), 2010, http://www.earthscienceliteracy.org/.
5. Haughy, Carey, October 1996, Geologist, Blue Mountain Minerals, 24599 Marble Quarry Rd., Columbia, CA, 95310, (209) 533-0127, pers. comm, http://www.bluemountainminerals.com/.
6. Higgins, Chris T., 1997, “Mineral Land Classification of a Portion of Tuolumne County, California, for Precious Metals, Carbonate Rock, and Concrete-grade Aggregate”, (with assistance on digital processing from students and staff, Columbia College, Columbia, California, and staff, Tuolumne County Planning Department), California Dept. of Conservation, Division of Mines and Geology, DMG open-file report ; 97-09.
7. Hittell, Theodore, 1898, “History of California”, Volume 3, San Francisco, N. J. Stone and Company.
8. House, M. R. (n.d.). Devonian Period. Retrieved June 02, 2017, from https://www.britannica.com/science/Devonian-Period#ref585568.
9. Konigsmark, Ted, 2003, “Geologic Trips: Sierra Nevada”, GeoPress.
10. Lindgren, Waldemar, 1911, “The Tertiary Gravels of the Sierra Nevada of California”, Professional Paper 73, Department of the Interior, United States Geological Survey.
11. Putnam, Roger, (pers. comm.), May 2017, Professor of Earth Science, 11600 Columbia College Drive, Sonora, CA, 95370.
12. Rohlen, Ginger, (pers. comm.), June 2017, Teacher, Sierra Waldorf School,19234 Rawhide Rd., Jamestown, CA., 95327.
13. Schweickert, Richard, 2006, “Accretionary Tectonics of the Southern Part of the Western Sierra Nevada Metamorphic Belt” (modified from a 1999 guidebook article by Schweickert, Girty, and Hanson), in J. Tolhurst (ed), “Geology of the Central Sierra”, National Association of Geoscience Teachers Far Western Section Fall Conference field guide, p. 55-95.
===============================================================================