HEAD OUT ON TO THE HIGHWAY: KANSAS, COLORADO, BLACK HILLS

The buffalo isn't as dangerous as everyone makes him out to be. Statistics prove that in the United States more Americans are killed in automobile accidents than are killed by buffalo.

Art Buchwald 

Traveling west!

Off to the field: we learned to collect early in life.

Breakfast in the sticks, southwestern Wyoming. 

My dad planned field trips every summer, usually hauling along students and lots of gear.  My brother was always ready to travel--see above pic.  Most of the time we camped in the sticks and I was pleased to get my cereal and milk--see above pic.  He still is hitting the road all these years later—but refuses to sleep on the ground!  Even today any time someone hollers “road trip,” my brother and I start singing Head out on the highway, lookin' for adventure. Life was good growing up as we never knew where the ole geologist was going to take us but it usually involved gravel roads and mom cooking over a campfire. In the early years we (both of us at age three months) stayed in a big tent but later we enjoyed the comforts of a tent trailer. Dad hauled that trailer to southeastern Canada to the mountains west of Banff to the desert near San Diego to southern Indiana and all points in-between. Not many kids my young age had the joy of eating fresh lobster sitting on rocks in Maine enjoying the ocean view.  That sort of contrasted with collecting and playing with cow bones from the sage lands of Wyoming.  Something from those early years of my life stuck as today I love camping, fishing, river rafting, snakes, traveling to the sticks, rock shows and collecting minerals and fossils.   The Daughter

I spent 21 years teaching geology at Fort Hays State University and my favorite courses were ones taught under the generic names of “Field Trips in Geology.”  The University sits in the middle of some of the finest, and most fossiliferous, Cretaceous (~145 to ~66 Ma) rocks in the United States.  What Kansas lacks in mountain geology is atoned for in the western half of the state by the magnificent vertebrate and invertebrate fossils collected from marine strata deposited in the Western Interior Seaway.

Xiphactinus (fish) skull collected from the Cretaceous rocks of western Kansas.

Throw in the famous marine invertebrates from older rocks of Pennsylvanian and Permian age (~323 to ~299 Ma) cropping out in eastern Kansas. Then savor the vertebrate and plant fossils from the Tertiary Ogallala Formation (and relatives ~16.3 to 4.9 Ma), and the various Pleistocene (Ice Age) sediments (with fossils) and one can easily observe a treasure trove of fossils.  Most travelers crossing the state from east to west on I-70, and in a hurry to reach the Colorado Front Range, miss the fantastic geology displayed in the road cuts.  It may be against the state law to pull off the Interstate ( I am not confessing to anything) and collect fossils; however, there are numerous exits and side roads.  One thing about Kansas is that with any sort of directional knowledge, or a GPS, you can never get lost.  Almost all roads are laid out in east-west or north-south directions and most are constructed every mile—that leaves a section of land (640 acres) between the roads.  There are “crooked” roads in Kansas and some section lines are “two-track” or less, but it is still hard to get lost!

The Western Interior Seaway was the dominant marine feature in the Late Cretaceous and divided North America into eastern (mostly erosion) and western (mostly mountain building) sections.  Map courtesy of the US Geological Survey.

CRETACEOUS STRATIGRAPHY WESTERN KANSAS

·       Pierre Shale

o   Various members

·       Niobrara formation

o   Smoky Hill Chalk

o   Fort Hays Limestone

·       Carlile Shale

o   Codell sandstone

o   Blue Hill Shale

o   Fairport Chalk

·       Greenhorn Limestone

o   Pfeifer Member

o   Jetmore Chalk

o   Hartland Shale

o   Lincoln Limestone

·       Graneros Shale

·       Dakota Formation

o   Various members

 

One of the very distinctive Cretaceous units in western Kansas is the Carlile Shale, a unit that was a great place to turn “loose” introductory geology students.  They learned to identify the formation and its three members by the following parameters: 1) the Fairport Chalk is the lowest member and conformably overlies the Pfeifer Member of the Greenhorn Formation.  Although the Fairport and the Pfeifer Members appear similar in rock types, we taught the students to remember that the fencepost limestone bed (an informal unit) separates the two units.  Well, if the Fairport and the Pfeifer look similar how would you identify the fencepost limestone bed?  The answer---to look for a thin bentonite bed that always underlies the fencepost limestone.  At times, the bentonite (altered volcanic ash) lies directly under the fencepost but in some localities the two are separated by a few inches.

An exposure in Russell County, Kansas, showing the gradational contact of the Greenhorn Limestone (P=Pfeifer Member) with the Carlile Shale (F=Fairport member).  The boundary is at the top of the fencepost limestone (FP) identified by the underlying thin bentonite layer (X).  Photo from Hattin (1962). 

A small quarry producing stone fence posts, Russell County, Kansas.  The Pfeifer Member is the upper unit of the Greenhorn Limestone and the fencepost bed marks the top of the member.  Above the fencepost is the Fairport Member of the  Carlile Shale. Photo courtesy of Kansas Geological Survey. .

The students could collect a gazillion inoceramid pelecypods (clams), and coiled ammonite cephalopods (mostly impressions), from the Fairport.  

Above the chalky beds of the Fairport are the dark colored mud rocks of the Blue Hill Shale, the middle member of the Carlile Formation (see Blog Posting September 26, 2013).  Students enjoyed picking around the Blue Hill since many locations yielded septarian concretions, shark teeth, and gypsum selenite crystals.  These rounded to semi-rounded septarian spheres usually contained nice calcite crystals and often produced fossilized ammonites and pelecypods (both in three dimensions).  The really prized fossil specimens from the Blue Hill are ammonites replaced, or at least partially replaced, by pyrite.  Hattin (1962) belived that both the septarian concretions and the pyrite are the result of diagenesis (some sort of physical, chemical or biological change after formation of the rock, in this case shale).

Large septarian concretion from Blue Hills Shale Member.

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Note "balls" of tiny calcite crystals in a large concretion void.

Note sharp erosional contact between Codell Sandstone Member of the Carlile Shale and the Fort Hays Limestone Member of the Niobrara Formation.  The Codell, at this locality, is gradational with the underlying Blue Hill Shale. 

The upper member of the Carlile Formation is the Codell Sandstone. The Codell is a “strange one” as in some places it is a true sandstone, but a silty one, quite distinguishable from the Blue Hill, while at other localities the unit is a sandy shale seemingly gradational with the upper Blue Hill. Many geologists are interested in the Codell due to the presence of numerous abraded teeth, dermal denticles, fecal pellets, and bones (fish and sharks).  In almost all localities the Codell is unconformably overlain, and has a sharp contact with, the Fort Hays Limestone Member of the Niobrara Formation.

Typical Fort Hays-Codell-Blue Hill profile in western Kansas.

The Carlile Shale is well exposed in southeastern Colorado, especially along the flanks of the Apishapa Uplift, and the valley cut by the Arkansas River near La Junta. On a field trip, several decades ago, we collected barite and calcite crystals from concretions that I presume were in the Carlile Formation.  This unit differs in several ways from the Carlile exposed near Hays, Kansas, (described above), most notably in the appearance of a new stratigraphic unit, the Juana Lopez.  The Juana Lopez is an enigmatic upper member of the Carlile and is a thin bed (zero to a few feet) of quartz sandstone and pebble conglomerate with numerous shark teeth and pieces of inoceramid (clams) shell---maybe reworked upper Codell??  For a detailed description of the Cretaceous units in southeastern Colorado see Kauffman, 1977).  His publication, as a Special Editor of The Mountain Geologist, is an amazing piece of work as several authors presented detailed road logs and photos of Cretaceous fossils from exposures near Salt Lake City to central Kansas.  I had the opportunity to attend this multi-day field trip and learned much.  The publication may be available at some of the used book sites on the Web.

Barite crystals collected from Carlile Shale, Otero County, Colorado.  There is a dusting of clay minerals on the specimen. The maximum length of the exposed vertical crystal is ~9 mm.

Cluster of calcite rhombs situated on the wall of a broken concretion collected from Carlile Shale in Otero County, Colorado.  Width of photo ~7.5 cm.

In my travels across the Plains I next found the Carlile exposed in western South Dakota, especially in Fall River County south of the Black Hills, and reported on calcite and selenite crystals from the Formation (Blog Posting April 2, 2014).  Today I report on some new specimens resulting from my insistent pounding on concretions.

Geologic map of Fall River County, South Dakota.  Arrow points to the small town of Edgemont.  Kc represents exposures of the Carlile Shale while Kp shows the large expanse of the Pierre Shale.  Map from martin and others, 2004.

The stratigraphy and nomenclature of the Carlile Shale in southwestern South Dakota changes significantly from exposures in southeastern Colorado. This is not an unusual occurrence as the Carlile, and its stratigraphic equivalents (for example the Benton Group or Formation), is a widespread unit extending from Utah to eastern Iowa/Minnesota and Texas north into the plains of Canada.   In the 1960s, the US Geological Survey mapped several quadrangles in Fall River County in their search for uranium.  The authors of these publications (such as Connor, 1963) described the Carlile as consisting of three members: 1) the upper Sage Breaks Member, a gray shale with abundant septarian concretions; 2) the Turner Sandy Member, a carbonaceous shale, sandstone and siltstone, containing a distinctive zone of septarian concretions 100 feet above the base; and 3) an unnamed shale member with gray shale with a calcareous base containing a thin prominent limestone.

Cappetta (1973), in describing an ichthyofauna (fish) from the Carlile “13 km from Hot Springs” (the County Seat of Fall River County), described the formation as “essentially marly with sandstone intercalations and layers of calcareous concretions.”

Martin and others (2004) described Carlile rocks on the State Geologic Map as: “dark-gray to black, silty to sandy shale with several zones of septarian, fossiliferous, carbonate concretions. Contains up to three sandstone beds near the middle of the formation and sandy calcareous marl at the base. Thickness 345-620 ft (105-189 m).”

Although the descriptions of the Carlile stratigraphy differ somewhat, at all locations the unit is overlain by the Niobrara Formation and underlain by the Greenhorn Formation---as in Kansas and Colorado.  I prefer the description offered by Martins and others (2004) since I just pound away on the concretions near Edgemont without paying much attention to any particular concretion zone.  Although many concretions yield broken calcite I was able to extract a tiny, water-clear terminated barite crystal from one mud ball.

Small water clear barite crystal approximately 9 mm in length.  Collected from a concretion in the Carlile Shale, Fall River County, South Dakota.

Fossils are common in many of the concretions and one particular mud ball yielded a nice ammonite cephalopod along with smaller, and less impressive, snails and clams.  All fossils were left in situ since it would be difficult, and most likely destructive, if I tried to remove them. The ammonite is probable a scaphite of some form although the suture lines and ribs are difficult to identify. 

A split concretion from the Carlile Shale produced several small specimens of clams (largest one has a width of ~6 mm) and snails.

Reverse of above concretion exposing a nice coiled  ammonite cephalopod (width ~3.1 cm.), probably of the genus Scaphites. 

 I have been attracted to the Cretaceous rocks in Edgemont area since wandering the outcrops while visiting with my student friends during my stay at the University of South Dakota. Today, the village of Edgemont is experiencing a great decline in population and businesses. In the mid-1960s Edgemont was a vibrant and booming town.  The uranium mines (ore from Cretaceous Inyan Kara Group) had a processing plant in town while a neighboring community named Igloo (actually Provo was the town) was the home of Black Hills Ordnance Depot.  This was an interesting place as tens of acres were covered by concrete structures (Igloos) storing army munitions and various varieties of not very nice poisonous gases.  The Depot employed thousands of workers (5000 plus their families) that either lived in housing at the base or in Edgemont. The railroad had a spur line running north to Deadwood and a roundhouse.   As a young man, I distinctly remember activities in the Stockman Bar in “downtown Edgemont” and one year a fairly “wild” Firemen’s Ball on the second floor of a local watering hole.  But alas, the Depot closed, uranium mining went away, logging is essentially non-existent, and the Stockman was closed and deserted as I toured the town in early September. The town has kept a school system with a high school.  I was always impressed with their mascot—the Edgemont Moguls. A mogul is a type of railroad steam engine called a 2-6-0, that is, two leading wheels (no power), six power wheels, and no trailing wheels.

During my early travels to Fall River County my geology buddies drug me (I went along willingly: road trip) to mineral and rock locations across the area.  During one particular foray, we stopped somewhere in the vicinity of Angostura Reservoir (northern part of the county) to look for fossils in the Jurassic Sundance Formation.  I was unfamiliar with the unit since Kansas does not have stratigraphic units of that age and the Missouri River Trench near the University in southeastern South Dakota also lacked Jurassic and Triassic rocks.  About the only Jurassic name I recognized was the Morrison Formation of dinosaur fame.

So, off we went to look for those strange sea creatures called belemnites, a squid-like cephalopod.  I had seen a few of these in Kansas collected from the Niobrara Formation; however, they were impressions and not too exciting.  The Sundance Formation is well known throughout its area of distribution for the abundance of fossil belemnites, often in some type of mass mortality setting.  The Sundance represents deposition in a shallow marine trough and in many areas rocks from the middle Triassic to the late Jurassic are “missing” due to erosion.  In places, the Sundance sits directly on the late Permian-early Triassic Spearfish Formation (see Blog Posting August 9, 2017).  In the latest Jurassic, marine waters retreated and the terrestrial Morrison Formation closed out the Period.

Belemnites collected from the Sundance Formation.  Most are broken guards; observe the "pointed" cigar shape of at least two specimens.  Width of photo is ~4.8 cm. 

Belemnites are often called “cigar fossils” since the preserved part of the animal is usually the calcite rostrum (or guard) that is a bullet-shaped and served as a rear counterbalance for the animal.  All hard parts of a belemnite were internal although many persons assume the guard is some sort of an external shell.  Little is known about the common mass mortality events where hundreds of belemnite guards are found in shallow water siltstones and sandstones.  Belemnites did not survive the great End of Mesozoic Extinction Event.

Artist's (Dmitry Bogdanove) reconstruction of belemnites.  Public Domain sketch.

Somewhere south of the Sundance and Carlile outcrops are large expanses of the younger Pierre Shale, a very well-known formation deposited in marine waters of the Western Interior Seaway (see numerous Blog Postings).  Back in the mid-1960s, during my little trips to the Black Hills with my buddies, we examined exposures of the Pierre.  I came out with a small cluster of bladed barite crystals. The specimen is really nothing special except it was collected over 50 years ago south of the Black Hills Dome and has survived numerous household moves around the country!

Cluster of bladed barite crystals collected Fall River County, South Dakota. Width of specimen ~1.7 cm.

Finally, rocks of the Lower Cretaceous Inyan Kara Group (Fall River Sandstone, Lakota Formation; see Blog Posting 3/24/14) in Fall River County have produced a “special mineral” that seems rare and generally unknown—sand barite crystals.  Sand calcite crystals are well known and easily found at rock and mineral shows.  I have documented my specimens from the famous Rattlesnake Butte (see Blog Posting 1/8/14), an area that is managed by the Oglala Sioux Parks and Recreation Authority and is located on the Pine Ridge Indian Reservation.  It is illegal to collect or sell fossils, artifacts and minerals on reservation land without a permit from the tribe.  Collectors also will find specimens (literally hundreds of them) of sand barite roses at shows and most are collected from localities in Oklahoma (see Blog Posting July 30, 2014).

The sand barite minerals collected from the Inyan Kara are not “roses,” as displayed in Kansas and Oklahoma, but prismatic crystals with pyramidal (although rounded) points. Roberts and Rapp (1965) described the crystals: “angular quartz grains…have been cemented by barite which has formed optically continuous single crystals …the crystals weather out as discrete single crystals or crystal aggregates…All crystals are elongated along the crystallographic B axis.”

Individual sand barite crystals; prismatic.  Length ~4.9 cm.

I presume these are penetration twins although the reentrant angles appear slightly different.  Perhaps they are, as Roberts and Rapp (1965) noted, "crystal aggregates."   Length of right group ~4.2 cm.

London (2008), in an article in The Mineralogical Record, noted that “[Barite] roses are mineral specimens, not rocks, because the shapes of rocks are indeterminate, whereas the shapes of minerals are determined by a combination of forms and habits derived from the interplay of crystal structure and environment of growth.”  Each of the petals of the rose are individual barite crystals just as the prismatic crystals from the Inyan Kara are individual crystals.

Rapp and Martin (1962) first reported on the South Dakota sand barite crystals and completed some cursory (probably high tech in 1962) examinations: 1: the crystalline barite is essentially pure BaSO₄; 2) an x-ray diffraction pattern showed no second compound in the barite cement; 3) the crystals contain about 36 % barite and 64% quartz (both by weight and volume). The South Dakota sand calcite crystals are approximately of the same composition—quartz to calcite.   I have been unable to locate additional information on either the South Dakota sand barite crystals or the formation of such.  I am not even certain if crystals are still available in the field or for purchase, or if there are other US localities.

So, my Fall 2017 trip to the black Hills and vicinity was interesting and certainly relaxing.  I am still hobbled by my new hip and use a walking stick; however, I managed to do some exploring and pounding.  Any day in the field, and camping at night, is a mighty fine day and adds an extra day onto your life.

Bad things do happen; how I respond to them defines my character and the quality of my life. I can choose to sit in perpetual sadness, immobilized by the gravity of my loss, or I can choose to rise from the pain and treasure the most precious gift I have - life itself.

                               Walter Anderson

REERENCES CITED

Cappetta, H., 1973, Selachians from the Carlile Shale (Turonian) of South Dakota: Journal of paleontology, v. 47, no. 3.

Connor, J.J., 1963, Geology of the Angostura Reservoir quadrangle, Fall River County, South Dakota; U.S. Geological Survey, Bulletin 1063-D.

Hattin, D.E., 1962,  Stratigraphy of the Carlile Shale (Upper Cretaceous) in Kansas: Kansas Geological Survey Bulletin 156.

Martin, J. E., J.F. Sawyer, M.D. Fahrenbach, D.W. Tomhave, and L.D. Schulz, L. D., 2004, Geologic Map of South Dakota: South Dakota Geological Survey.

Raup, G., Jr., and H. Martin, 1962, Sand barite, an analog of sand-calcite, Black Hills, South Dakota: The American Mineralogist, v. 47.

Roberts, W.L., and G. Rapp, Jr., 1965, Mineralogy of the Black Hills: South Dakota School of Mines and Technology, Bulletin no. 18.