BASALT AT PICACHO PEAK

HOMELAND OF THE HOHOKAM CULTURE.  Map courtesy of Wikipedia.

The rocks around Phoenix and Tucson, Arizona, contain numerous “artifacts” that point to the presence of an archaeological culture known as the Hohokam.  Residents in my home state of Colorado are perhaps most familiar with another group, the Ancestral Puebloans (commonly called Anasazi), an ancient Native American culture centered on the present-day Four Corners region.  However, in this part of Arizona the Hohokam reign supreme.  Like the Anasazi, little is known of the Hohokam descendants.  What we do know is that the Hohokam were very successful in their endeavors.  They built the Great House, now partially preserved at Casa Grande National Monument (see previous blog), and left behind untold numbers of petroglyphs on rock outcrops.  Vestiges of their extensive irrigation canals may be found as these agrarians farmed fields of cotton, squash, maize and beans.  They seemed to have occupied the areas along the Santa Cruz, Gila, and Salt Rivers from about AD 0 to ~1450.

While hiking in some of the smaller basalt outcrops near Picacho Peak (see previous blog) I came across some quite interesting features in the rocks.  These were circular in nature, perhaps four to five inches in diameter, and ranged in depth up to 10 inches.  The structures obviously were made by “people” and were most common near the entrance to small caves.  They are bedrock mortars, or morteros, where members of the Hohokam Culture ground mesquite beans for use as food.  They seem identical to features found at Pima County’s Los Morteros Conservation Area (Arizona) and Indian Grinding Rock State Historical Park.  This latter site, in the foothills of California’s Sierra Nevada Mountains, is a limestone locality where the local Native American population ground acorns. 

At any rate, the sight of these structures was a serendipitous moment and made me pause to reflect on the human history of the Sonoran Desert.  I could just picture in my mind a group of people grinding away and experiencing a social interaction, perhaps yelling at small children to get off the cliffs and watch out for snakes, and talking about the weather.  It was a pleasant thought. 

mike

MORTEROS NEAR PICACHO PEAK.

MORTEROS NEAR MOUTH OF SMALL CAVE.

BACK IN THE SADDLE AGAIN

SUNSET AT GILBERT RAY CAMPGROUND

Well, I am back on the web as my internet “hotspot” arrived today, and my spouse has let me use her computer!  So, if you might be thinking “what happened here” (or even if you are not), there is a sad story.  A week ago we traveled to the Phoenix airport to pick up my visiting daughter and her husband.  On the way home we stopped at a large truck stop in south Phoenix where three of us went in to purchase some food.  My spouse stayed by the vehicle with the dog.  She had just circled the pickup when a “perp” (I learned that word from TV) came up along her blind site, got into our vehicle, grabbed her purse and my laptop, and zipped away in a car picking “him” up.  Just like that we had lost a thousand dollars worth of “stuff” and my spouse’s identity.  You can just imagine the visits to the bank, telephone company, hotspot company, etc.  Next will be the Drivers License Bureau, a key cutting company, eyeglass company, etc.

The "good thing", if there is such, is that my wife was not injured--I am very thankful.  We can replace the “stuff”, but at a cost,  but can never replace ~250 photos I had not copied onto an external drive nor about four completed written articles.  But perhaps most importantly, I am not certain that my trust in people, especially strangers, will ever return. 


mike

SUNSET AT PICACHO PEAK

HIKING PICACHO PEAK

PICACHO PEAK (FAR LEFT).

I currently am camped at Picacho Peak State Park, north of Tucson about 30 miles, and south of Casa Grande about 20 miles.  It is one beauty of a place to spend some time if isolation is of interest.  Although the park is adjacent to Interstate 10, I can sit in my lawn chair and watch the sun go down over mountain ranges perhaps 40 miles away.  It seems that the only “things” between my chair and the mountains are hundreds of saguaro cacti.

Picacho Peak is sort of a misnomer since Picacho is a Spanish word for “big peak” so a translation would be big peak peak.  Whatever the case, it is a fantastic place to camp and hike.  The Park is in the Basin and Range Physiographic Province so most of the many mountain ranges that I see from my easy chair are horsts (uplifted blocks) separated by expansive grabens or half-grabens (down-dropped blocks).  The grabens are now large alluvial basins.  Periodically there are outcrops of volcanic rocks (see previous blog on Ragged Top).

The Park’s main attraction is Picacho Peak, a large chunk of basalt that has been tilted and faulted.  In fact, much of the basalt flow(s) is now hidden under the alluvial fill.  It is my understanding that the volcanics at the Park are about 22 Ma and represent the top plate of a large detachment fault (large normal fault) with the bottom plate being the Precambrian granite and gneiss east across the Interstate—the Picacho Mountains (Kresan, 1987).  I located several instances of old mining structures, mostly glory holes and simple excavations.  The miners evidently were after copper since most of the mines seem to follow greenish-blue stained rock; breccias associated with faults also were common targets. The detachment provided a conduit for hydrothermal fluids that charged the upper-plate rocks with mineralizing fluids that carried Zr and Ba, along with Au, Ag, and Cu, during detachment 17–18 Ma (Brooks, 1986).

As an avid hiker I decided to take my afternoon stroll to the top of Picacho Peak situated at 3374 feet with an elevation gain of approximately 1500 feet in 2.1 miles.  Little did I know that my walk would turn into “a really, really, hard hike”.  The first 900 feet of elevation gain was OK and got me to a saddle, and then I saw something on the other side that made my heart go pitter-patter a little faster.  I needed to go back down before going up again (always a bad sign) and the path down was between two cables, and steep, very steep!  That was only the beginning for the remainder of the hike was always in sight of cables with some climbs 70 degrees.  In another place I had to hold the cables and wiggle up a crack in the basalt—climbs like that are hard on an old guy.  And speaking of age, one of the high school kids sort of hiking with me (I was explaining geology—never miss a chance for that) asked, “Say, how old are you?  You hike pretty good for an old guy”.  The hike ended up about four hours in length with a net gain of 2366 (not 1500) feet in the 2.1 miles.  Old guys rock!

REFERENCES CITED

Brooks, W. E., 1986, Distribution of Anomalously High K₂O Volcanic Rocks in Arizona: Metasomatism at the Picacho Peak Detachment Fault: Geology, v. 14, no.4.

Kresan, P. L., 1987, Arizona Geology: An Aerial Tour: Arizona Bureau of Geology and Mineral Technology Fieldnotes, V. 17, No. 3.

mike

THE NEED TO WIGGLE UP A CRACK!

A FAIRLY STEEP SLIDE.

A NETWORK OF CABLES LEADING UP (AND DOWN).

MADE IT TO THE TOP. PICACHO MTNS. IN BACKGROUND.

A VIEW FROM THE EASY CHAIR.

RAGGED TOP: TERTIARY RHYOLITE

Ragged Top is an interesting mountain located in the Silver Bell Mountains west of Tucson, Arizona, and in the newly designated (Clinton Administration) Ironwood Forest National Monument,   The Silver Bells have complexly folded and faulted igneous, metamorphic, and sedimentary rocks that range in age from the Precambrian to Quaternary (Kreidler, 1987).  Ragged Top is a mass of Tertiary rhyolite that may represent a volcanic neck or a hypabyssal stock.  The peak gets its name from the massive erosion that has left behind spires and sharp-pointed peaks.  There is an elevation gain of about 1767 feet from the desert floor (2140 feet) to the summit (3907 feet) and the hiking trail (mostly just bushwhacking) is quite strenuous.  Ironwood Forest National Monument features plants of the Sonoran Desert, including the desert ironwood, a shrub-like tree that has beautiful purple flowers in the spring.  In addition, there are a number of Hohokam petroglyph sites in the Monument.  But I believe that the major scenic feature is the majestic Ragged Top.

REFERENCES CITED

Kreidler, T. J., 1987, Mineral Investigation of the Ragged Top Wilderness Study Area (AZ-020-197), Pima County, Arizona: U. S. Bureau of Mines  Mineral Land Assessment Open File Report 80-87.

mike

CSMS GROUPS ARE ACTIVE!

The Colorado Springs Mineralogical Society (CSMS) has a number of active subgroups that meet on a regular schedule.  Visitors and new members are always welcome.

Kerry Burroughs leads the Crystal Study Group whose members are dedicated to the discovery, identification and study of crystalline minerals of all types.  The Group specializes in the recovery and preparation of numerous local minerals for which the Pikes Peak region is world renown, especially Amazonite, Smokey Quartz, Topaz and Fluorite.  The Crystal Study Group meets every 4th Thursday at 7:00 PM in the Senior Center.  Additional information: info@csms.us

The Faceting Group, led by Paul Berry, meets in the Senior Center on the 4th Thursday at 7:00 PM.  The group has use of faceting machines housed in the Center and members turn out a variety of spectacular gem and semi-precious specimens. Additional information: info@csms.us

The Fossil Study Group organizes meetings around the interests of the members. Programs are scheduled, fossils identified, paleontological discussions held, and collecting techniques discussed. Members are encouraged to lead field trips to prospective collecting localities. In addition, each member brings to the meetings fossils for "Show and Tell".  Jack Null coordinates the “case” entered into the annual CSMS Show.  Although Mike Nelson is listed as leader, many other members offer presentations and identification skills.

Meetings are generally scheduled for the first Tuesday of the month at 7:00 PM at the Senior Center. However, the Group does not meet during June, July and August unless a field trip is scheduled.  It is best to contact Mike at www.csrockguy.yahoo with questions.

The following presentations are scheduled:

March 1 Presiding and presentation (Glen Eyrie fossils): Jack Null

April 5 Presiding and presentation: Jerry Suchan

May 3: Presentation (History of Florissant): Steven Veatch

The CSMS Micromount Group is interested in the collection and preparation of very small mineral specimens best viewed under a microscope.  The Group specializes in looking at tiny specimens of quite rare minerals, and displaying fantastic sprays of very delicate crystals that could not even exist on a larger scale.

The Micromounters, led by Phil McCollum, meets every 2nd Tuesday at the Senior Center.  Additional information: info@csms.us

The Lapidary Group meets on a regular/irregular schedule on the 1^st Saturday of the month, noon, at a member’s home; therefore, interested participants should contact info@csms.us for additional information.  The members learn to perfect the art of cutting and polishing minerals and then mounting the finished products into jewelry settings.  The most common products resulting from this work are the cabochons, either free form or standard.  Sharon Holte leads the Lapidary Group.

Whereas the Lapidary Group works with minerals, the Jewelry Group constructs or builds the settings.  Members become proficient in silver smithing, silver soldering, wire wrapping, and lost wax casting.  This group is led by Bill Arnson and meets on a regular/irregular schedule at noon on the 3^rd Saturday of the month.  It is always best to contact Bill at ritaarnson@msn.com

CSMS has two quite active youth groups, both led by Steven Veatch and his associates.  The Pebble Pups includes children of all ages and meets the third Thursday of the month, 6:10 to 7:15 PM at the Senior Center.  The Juniors, mostly of junior high age, meet the same evening, same location, 5:15 to 6:30 PM.  The study periods include lectures, explanations and hands-on laboratories; participants often receive actual specimens for their personal collections.  The leaders also sponsor some individuals via the internet so check with Steven Veatch at info@csms.us

CSMS and RMFMS Annual Show

On June 24-26, 2011, the Colorado Springs Mineralogical Society (CSMS) will celebrate its 75^th anniversary by hosting the Rocky Mountain Federation of Mineralogical Societies (RMFMS) Annual Show and Convention (70^th anniversary), the 48^th annual Pikes Peak Gem and Mineral Show, and the 3^rd annual Rock Fair at WMMI (Western Museum of Mining and Industry).  The Best Western Academy Hotel at 8110 N. Academy Blvd. will host the activities of the Federation and the indoor Pikes Peak Show.  The WMMI at 225 North Gate Blvd., Colorado Springs (across from the US Air Force Academy) will play host to the outdoor Rock Fair.  The two localities are very close to each other at the north end of Colorado Springs and are near Interstate 25.  The events are under the leadership of Show Chair Ron “Yam” Yaminokoski at yamofthewest@gmail.com.

The theme for the events is Colorado’s Mining Heritage and several speakers will have presentations at the Federation activities.  In addition, CSMS members will be presenting several talks throughout the period at the outdoor show (actually there are a few rooms inside for such activities as the talks).  The WMMI is a natural location for events associated with our mining heritage as the 27 acre museum includes both indoor displays and outdoor exhibits such as an operating stream shovel.  See the museum web site at: http://wmmi.org/home.

CSMS will utilize both the WMMI and the hotel to display submitted cases. The competitive cases will be displayed at the convention hotel where all judging will take place.  The non-competitive cases will be featured at the WMMI.  CSMS cases will be available for those making prior arrangements.

CSMS has strong programs with both Pebble Pups and Juniors so there will be numerous activities for children (of all ages).  Perhaps most interesting will be the gold panning area operated by the local Gold Prospectors of Colorado club.  Always a big hit, beginners may learn to “pan gold” and actually keep what they find! 

A vibrant Silent Auction will be running at WMMI and all proceeds will benefit our scholarship program (geology/earth science majors in a collegiate environment).  Numerous vendors at both localities will have a wide variety specimens and equipment for sale.  Pre-meeting field trips start June 19 while post-meeting trips conclude June 29 so plan accordingly.

This outstanding summer event promises to offer ‘something for everyone” and so CSMS invites participants to the great city of Colorado Springs where you will be able to observe Pikes Peak (14,115’) every day!  Check the Federation web site at www.rmfms.org for continuing details or contact the Show Chair (yamofthewest.yahoo.com).

mike

FACETED SPURS: SIGNS OF MOVEMENT

THE PATRIARCH, OR IS IT MATRIARCH?

Faceted spurs are common, fairly easy to recognize, landforms found along the flanks of mountains in the western U. S. where active, or recently active, faults are present.  As the mountain ranges are uplifted, streams cut into the rocks and flow toward master streams located in the down-dropped and adjacent valleys.  Ridges are formed between the mountain streams and usually slope gently toward the adjacent valleys.  However, if bounding faults are active, a fault scarp (cliff) forms along the edge of the mountains.  This scarp has the tendency to truncate the interfluve ridges (spurs) and create a triangular shaped “faceted spur”.  Along the west flank of the Catalina Mountains north of Tucson, Arizona, the bounding Pirate Fault has created numerous faceted spurs that are quite evident from Catalina State Park.  These triangular features seem common on outcrops of the Tertiary Wilderness Suite Granite.

In south central Colorado, the east side of the San Luis Valley is bounded by the Sangre de Cristo Fault along the western side of the Sangre de Cristo Range.  The northern part of the range, usually referred to as the Culebra Range, is separated from the adjacent San Luis Basin by the Crestone Section (a large normal fault = mountains “up” and basin “down”) of the master Sangre de Cristo Fault (Ruleman and Machete, 2007).  This fault extends from Poncha Pass, the northern-most boundary of the San Luis Basin, south to the Great Sand Dunes (McCalpin, 1982).  The deepest part of the basin seems to lie adjacent to the Crestone Section where there may be 30,000 feet of sediment (Garca and Kind, 1965). 

The Culebra Range and the adjacent Crestone Section Fault are characterized by a steep-walled mountain front with well-developed faceted spurs.  Many of the fault scarps are developed on very recent late Pleistocene and Holocene alluvial deposits.  (McCalpin, 1982, 1986).  This would indicate movement along the fault within the last 10,000 years.

REFERENCES CITED

McCalpin, J.P., 1982, Quaternary Geology and Neotectonics of the West Flank of the Northern Sangre de Cristo Mountains, South-central Colorado: Colorado School of Mines Quarterly, v. 77, no. 3.

McCalpin, J.P., 1986, Quaternary Tectonics of the Sangre de Cristo and Villa Grove Fault Zones, in Rogers, W.P. and Kirkham, R.M., eds., Contributions to Colorado Seismicity and Tectonics—A 1986 update: Colorado Geological Survey Special Publication 28.

 Ruleman, C. and M. N. Machette, 2007, An Overview of the Sangre de Cristo Fault System and New Insights to Interactions Between Quaternary Faults in the Northern Rio Grande Rift in Ruleman, C., M. N. Machette, M-M. Coates, and M. L. Johnson, eds., 2007 Rocky Mountain Section Friends of the Pleistocene Field Trip—Quaternary Geology of the San Luis Basin of Colorado and New Mexico, September 7–9, 2007: U. S. Geological Survey Open-File Report 2007-1193. 

mike

WEST FACE OF SANTA CATALINA MOUNTAINS.  THE PIRATE FAULT LIES UNDER THE SEDIMENT AS THE MOUNTAIN FRONT HAS RECEDED.  THE FACETED SPURS ARE GEOLOGICALLY OLDER (TERTIARY) THAN SIMILAR FEATURES ALONG THE SANGRE DE CRISTO MOUNTAINS.

WEST FACE OF THE SANGRE DE CRISTO MOUNTAINS AT NORTHERN END OF THE SAN LUIS VALLY.  MOVEMENT ALONG THE CRESTONE FAULT IS GEOLOGICALLY YOUNGER THAN THE PIRATE FAULT IN ARIZONA.

GOOGLE EARTH IMAGE OF SANTA CATALINA MOUNTAINS AND ADJACENT FEATURES.

GOOGLE EARTH IMAGE SHOWING EXTREME NORTHERN END OF SAN LUIS BASIN AND ADJACENT FEATURES.