Tag Archives: STATEMAP

Statemap 2015-16 Update

 

Hello all!

Well, another year, another map!  The Brownsville quad is now published (see map below), and a link to it will be posted on our website soon.  This year marks the 22nd anniversary of Statemap, aka the National Cooperative Geologic Mapping Program, in Arkansas.  Statemap is partially funded by a USGS grant, and was established to encourage the states to map their surface geology at the 1:24,000 scale.  To date, our mapping teams have completed thirty-three quadrangles in the West Gulf Coastal Plain and, with the recent publication of the Brownsville quad, forty quads in the Ozark Plateaus.

Geologic map Brownsville, AR

The geology of the area around Greers Ferry Lake has never been mapped in great detail until now.  Previous work had been to produce the 1:500,000-scale Geologic Map of Arkansas.  Because we mapped the Brownsville quad at the 1:24,000 scale, we were able to make some observations new to science.  A fault was discovered that had never been mapped previously.  We named it the Shiloh Fault for the old town, now inundated by the lake, that lies along its trace.  Meanders of the Little Red River channel approached this fault but didn’t cross it, probably due to encountering more resistant rock on the north side of the fault.  The Witts Springs Formation had not been mapped south of the Choctaw Creek Fault before, but we were able to draw in its upper contact with the Bloyd Formation along the Devil’s Fork and several other drainages.

Overturned cross beds in massive sandstone of the undifferentiated Bloyd Formation

As on other quads around Greers Ferry Lake, we continued to find terrace deposits left behind as the Little Red River carved the valley down to its present elevation.  Some of these are stranded as much as 260 feet above the current channel bottom (now located on the bottom of the lake).

DSCN0999

For many years now, our mapping program has focused on completing the Mountain View 1:100,000-scale quad.  This area encompasses thirty-two 1:24,000-scale quads and stretches from Richland Creek to Sylamore Creek on the north side and from the Illinois Bayou to Greers Ferry Lake on the south side.  Now that this area is finished, our Statemap Advisory Committee has decided we should jump over to northwest Arkansas to complete work on the Fly Gap Mountain quad, just west of the Mountain View quad (see map below).

STATEMAP index for blog

So for next year, the Statemap team is going to start work on the Durham quad in the northwest corner of the Fly Gap Mountain quad near Fayetteville.  We’ll have to spend a few weeks getting our feet on the ground, so to speak, because we won’t have the benefit of already mapped quads adjacent.  Fortunately, we will be very close to the type-sections for most of the formations we’ll be mapping, so hopefully, we can study the classic outcrops and trace them into our new field area without too much difficulty.

DSCN0704

A type-section is an area, or even just an outcrop, where a particular formation was first described.  They are named after a local geographic feature.  Formations first described in northwest Arkansas include: the Fayetteville Shale, the Pitkin Limestone, and the Hale Formation which has the Cane Hill and Prairie Grove as members.  Members are smaller, discernable units within a formation.  The type-section for the Bloyd Formation, including the Brentwood, Woolsey, Dye, and Kessler Members, and the Trace Creek, which is the basal member of the Atoka Formation (named for its type locality in Oklahoma), is on Bloyd Mountain near West Fork.

I would like to take this opportunity to thank my field partners that accompanied me this past year.

DSCN2086

I started the year with Ty Johnson, who has since moved into a permanent staff position at the Survey, so congratulations to him!  He was with me for just a year, but we covered a lot of ground together.  He’s now mapping the geology of the Lake Ft. Smith area with an emphasis on landslide mitigation.

DSCN2258

The writer and also principle investigator of the Statemap grant, Angela Chandler, went out a few weeks in the late fall before we could fill the vacancy Ty left behind.  No matter how much I learn, she always manages to teach me something new.

DSCN2641

We hired Garry Hatzell, a recent U of A grad, who started fieldwork in January.  He brings an enthusiastic knowledge of paleontology to the mix, and I look forward to his continued insight into the biostratigraphy of our field areas.

Without the help of these fine folks, we couldn’t have gathered the data or produced the map.  Also, I would have been stuck in the office—a torture for the unrepentant field geologist.

Wish us luck on the Durham quad!  And if you’re in northwest Arkansas during the next twelve months and happen to drive by a Jeep Cherokee with the AGS seal on it, be sure to stop and introduce yourself.

 DSCN3153

Until then, I’ll see you on the outcrop!

  DSCN2275       

Richard Hutto

Statemap 2014-15 Update

2014-08-04 006

Hello all,

Just wanted to let you know that the Statemap 2014-15 field mapping project has resulted in the publication of three new geologic maps.  These are the Parma, Prim, and Greers Ferry quadrangles.  Reduced images are posted below.  These should be available as .pdfs on our website in the near future.  I’ll keep you posted!Parma

Parma Quadrangle

2014-09-15 013Prim

Prim Quadrangle

Prim boulder (cannonball concretion) in Sugar Camp Creek

Greers Ferry Layout

Greers Ferry Quadrangle

Old Terrace deposit underlying Greers Ferry, AR

Also, I would like to thank the many people who helped with data collection in the field this year, without whom this project would have been impossible.

2014-07-15 037 (2)2014-07-21 004

Andy Haner                                                        Danny Rains

 

2014-09-03 0052014-09-16 003

Angela Chandler                                                                     Stefanie Domrois

 

2014-10-15 010DSCN9627

Doug Hanson                                  Ty Johnson

Thanks, everyone!

 

Now it’s off to the Brownsville quad for next year!

DSCN0255

Richard Hutto

Link

2014-02-11 046

Hello all! Sorry I haven’t blogged in awhile. I’ve been so busy trying to complete the maps for this year by the June 30th deadline.  But, I am proud to announce that the Geologic Maps for Shirley and Fairfield Bay are now published and available on our website!  Click below to view and download the maps.

http://www.geology.ar.gov/maps_pdf/geologic/24k_maps/Shirley.pdf http://www.geology.ar.gov/maps_pdf/geologic/24k_maps/Fairfield%20Bay.pdf

The process to create these maps takes an entire year. I kept you updated each field week from July to April last year, so I thought you might be interested to know how we take the raw data we collected in the field and use it to make a map. First of all, it’s a collaborative effort.  It takes a lot of people who specialize in various disciplines working together to make this product.  Basically, drawing the map starts with the notes we took in the field.  At each point, we tried to identify the rock formation exposed there.  Sometimes this was difficult, especially in the southern portion of the Boston Mountains Plateau where we worked this year. These rocks are all so similar–mostly sandstone and shale.  Nevertheless, if you cover as much ground as we did, you begin to discern similarities in the rock types and bedding structures, and can make formation calls based on those similarities.  Many of the points are taken on what we considered to be contacts between different formations.  These points are used to hand draw contact lines on a blank topographic base map. 2014-07-11 0032014-07-11 007 These lines are continued into areas where the contacts may not be exposed, because we assume lateral continuity of these units.  Many times there are topographic breaks along these contacts which can help us draw the lines in areas of poor exposure or in areas we just didn’t get to.  Structural lines are drawn along the trace of faults or other structures at the surface in areas where we saw the hallmarks of faulting such as deformation bands and non-vertical joints.  Also, the many strike and dip measurements we took were plotted on the map and helped determine orientation of faults and other structures, such as the axis of a monocline.  Once all the lines were neatly drawn on the topo, it was scanned into the computer and georeferenced to the grid of all quads in the state.  Next, each line was painstakingly digitized in ArcView by one of our cartographers, in this case Brian Kehner.  The digitized map was then added to a layout that Danny created in Adobe Illustrator. 2014-07-11 008

The layout includes descriptions of each formation developed from our field notes and are specific to each quad.  A correlation of map units, a generalized stratigraphic column, an inset map of the locations of the field points, a symbol chart, and a rose diagram of the frequency of each joint direction are also added to the layout.  A cross-section based on formation thickness is hand drawn, digitized, and placed along the bottom of the layout. Formations are symbolized by color and an abbreviation.  Sometimes photos are added to balance the layout.  Also plotted are any quarries or pits we found or were in the economic commodities database we keep at the Survey.

2014-07-11 012 After we have a reasonably good map, it’s printed and set out for staff review.  They really let us have it, but this editing process always greatly improves the maps.  After two or three revisions, we finalize it and send it to the USGS by June 30 to fulfill the requirements of the STATEMAP grant.  Whew!  What a relief!Geologic Map of Shirley red1 Geologic Map of Fairfield Bay red This year, as in years past, I have designed a commemorative STATEMAP t-shirt.  I’m taking orders until July 25th if anyone is interested.  They are available for the cost of the shirt you choose plus the printing.  Please email me at richard.hutto@arkansas.gov for details. AGS14_shirt_front (1)AGS14_shirt_back (1) Now we get ready to head back out again to our new field area.  This year we’ll be mapping the Parma, Prim, and Greers Ferry quads.  I’m breaking in a new field partner this time out.  Andrew Haner says he’s looking forward to seeing some of the Arkansas wilderness.   I just hope the snake count is low this year.  From what I’ve see so far, the ticks seem to be at an all time high.  I’ll try to keep you posted, but will be out of the office four days a week this year.  That will leave little time for blogging.  So until my next post, I’ll see you on the outcrop! Richard Hutto

Statemap Field Blog, April 7-9, 2014

2014-04-07 006

Hello all,

Well, this is the last week of field work for the 2013-14 season.  Of course, there’s always more one would like to have a look at, but we have to stop sometime.  On Monday, we started down by the M&NA railroad bridge at Shirley.  The big fault that makes the SW/NE lineation goes through here somewhere, but it’s difficult to say where exactly.  There are lots of non-vertical joints and deformation bands in the area, which are all good fault signs, but nothing very definitive.  The area north of the bridge is about as thick as it could possibly be with greenbriers –only passable with much effort and many scratches.  We saw very thick-bedded sandstone there which we took for Witts Springs that day, but when we came back on Wednesday, we decided it may be north of the fault, and therefore would be Imo.  We have Imo across the valley, so it’s not out of the question to have it here, but it may be just a relatively thin slice.  There are many cut and fill channel beds there, some of them with very nice soft-sediment deformation at the margins.

On Tuesday we finished up some loose ends in the northwest corner of the Shirley quad.  After we climbed way down in a hollow that had an old tornado track going through it, Danny realized he had lost his camera somewhere.  We hiked back up to the Jeep to see if it was there (it wasn’t), then retraced our steps from earlier that morning.  Still nothing.  He remembered the last time he had used it was in that horrible briar patch the day before, so after we climbed out again, we headed back there.  Sure enough, in the thickest part of the patch, where he had been practically crawling to get through, a briar had reached in his carrying case and pulled it out.  It was still dangling there about a foot off the ground right on the river bank.  At least we got it back!

Deformation bands in massive sandstone near Middle Fork north of Shirley2014-04-07 017

2014-04-09 026 2014-04-09 011On Tuesday afternoon, we went down a drainage on the west side of Middle Fork looking for more signs of a fault we have traced from the Old Lexington quad.  We definitely found a lot of deformation bands in the Witts Springs massives down there and figure there might be as much as 80 feet of throw on the fault.

2014-04-08 0192014-04-08 027Wednesday was our last day in the field this year, and we spent most of our time on the Middle Fork just north of Shirley where we had left off on Monday.  Did look like the fault goes through there because we found very-thick bedded massives on the north side (Imo) and shale interbedded with very thin-bedded sandstone on the south side (Cane Hill).  Our last couple of hours we spent getting points in several road cuts in and around Shirley.  We took a final photo in front of the town sign.

2014-04-08 048 (2)2014-04-09 047This will be Danny’s last year out in the field with me, so I’d like to take this opportunity to thank him for putting up with me and the sometimes horrendous field conditions we’ve faced together the last five years.   Looks like I’ll have to break in a new field partner next year, so should be interesting.  Now comes the time of year when we have to sit in the office and draw the maps, create the layouts, and finish the database, all to be turned in to the USGS by June 30.  It seems like a long time, but we’re always editing down to the last minute.  By the time we make it back out in the field, it will be mid-July, so the ticks and snakes will be out in full force, it will be nice and hot, and all the vegetation will be full grown.  At least that gives us something to look forward to.  Until then, I’ll see you in the office.  After that, I’ll see you on the outcrop!

 

 

 

Statemap Field Blog, March 31-April 2, 2014

 

2014-04-01 075

Hello all!

Another great week in the field.  Signs of spring are everywhere, and unfortunately the field season is drawing to a close.  We skipped around all over the Fairfield Bay quad this week, still trying to trace the very thick-, massive-bedded sandstone that we’re calling the base of the Bloyd for now.  Just off the eastern edge of the Fairfield Bay quad is a locally famous outcrop of that sandstone that was supposedly visited by Hernando Desoto himself in 1542.  Whether or not that’s true, it is a very impressive bluff shelter known as the Indian Rock House.  A lot of eroded material was removed from the floor of the shelter when the adjacent Indian Hills Golf Club was built, leaving behind the fine sandstone amphitheater we see today.   One could see how this formation could later become a natural bridge if erosion continues along the joint set parallel to the bluff face.  If that interior arch were to fall out, then the remaining one would form a bridge.  This is how most of the sandstone natural bridges in Arkansas are formed.  Lots of graffiti has been scratched into the friable rock over the years, including some that may have been carved by native people.

2014-04-01 0802014-03-31 013

On Tuesday, we finished up our field work on the lake.  We still had a couple islands we needed to visit, and the entire south side of the lake is so steep that access by land would be difficult.  We were excited to find more old river terraces on the islands, including one that would have been deposited on a cut-off meander in the area of Harpers Cove.  The deposit is about 80 feet above and over a half mile north of the current river channel (before the lake was there, that is).  The high end of the range for the downcutting rate for the Colorado River in the western Grand Canyon is 16 centimeters/1000 years, and I think we can all agree that downcutting there probably exceeds that in Arkansas.  Using that rate, an estimated 152,000 years would have passed since that terrace was deposited.  That gravel has been there a long time!  Of course, cutting off the meander would have stranded that deposit at that time, but don’t forget that this stream is developed in bedrock, so meander cut-off would be a fairly infrequent event.  To get a better estimate of these events, methods such as luminescence dating are being developed to age date the sand in these stranded river terraces.  With this new technology, perhaps someday we will know when these terraces were deposited.

2014-03-31 0182014-04-01 053

2014-04-01 023

2014-04-01 0352014-04-01 005

On the south side of lake below Stevens Point is a good example of a modern landslide, and a bit of a cautionary tale.  Sometimes clearing trees for roads and houses can have catastrophic results.  The photo tells the story.  The major part of this landslide occurred March 28, 2005 just after a road was cleared from the house down to the lake.  Most of the material at the edge of the lake on the north side of Hunter Mountain is there as a result of old landslides, therefore any development in this area can cause it to become unstable, as evidenced here.  That’s why part of our project includes mapping areas where landslides have occurred.

2014-04-01 049

Speaking of Hunter Mountain, we ran across one of the now ubiquitous gas well pads up there, and I thought you might be interested to know the function of each piece of typical well head production equipment.  At each wellhead is a set of valves that regulate the flow of gas.  These are often controlled remotely, thus the solar panels which power the system.  The big tanks near them contain hydrogen sulfide which is introduced into the gas right away to give it a strong odor.  This odor is, of course, quite useful to determine if there are any gas leaks since natural gas is odorless.  From the wellhead, the gas flows to the separators which remove any fluids contained in the gas.  This fluid could include heavy hydrocarbons, but is mostly produced water.  These fluids are stored in large tanks which are built inside a berm.  The berm is designed to hold 1 1/2 times the capacity of one of the storage tanks in case of a spill.  The level in the tanks is also monitored remotely and emptied on a regular basis.  From here, the gas is piped to a compression station where it undergoes further treatment.   Then it is sent through a transmission line and on to your house.  It’s not pretty, but for now, we have to have it.

2014-04-02 0102014-04-02 0112014-04-02 012

Well, next week will be the last of our field season.

Until then, see you on the outcrop!

 

Statemap Field Blog March 24-26, 2014

Taphoni (honeycomb weathering) in massive sandstone.

Taphoni (honeycomb weathering) in massive sandstone.

Hello all!

Sorry about that long hiatus, but I had a couple of extra projects the last couple months that took a lot of extra time.  We’ve been in the field almost every week except for March 3-5 during the 3 inch snow in Van Buren County.  We’ve mostly worked on the Fairfield Bay quad during the last few weeks.  This week was spent tracing a very thick-bedded, massive sandstone unit through the town of Fairfield Bay itself.  It is quite an impressive bluff-former and actually underlies almost the entire Mountain Ranch golf course.

2014-03-24 017

Danny descending treacherous massive sandstone outcrop

2014-03-24-002.jpg

Danny contemplating how this massive sandstone can all but disappear a few hundred yards north of here

 

2014-03-24 028

Grotto in massive sandstone

2014-03-25 001

Most hillsides are composed of a thick sequence of very thin sandstone/siltstone and shale–easily erodible

 

Apparently some structure or perhaps a change in depositional environment made this sandstone climb up 200 feet to the east.  There it forms the cap of the ridge on which the small town of Fairfield Bay sits.  Moving east again, It underlies the Indian Hills Country Club where weathering (and earth-moving equipment) has produced the famous Indian Rock House on the golf course there.  Underlying that massive across the entire area is a very thick sequence of very thin-bedded sandstone/siltstone/shale.  A lot of the roads built in this unit have formed deep gullies making some of them impassable.  Still, there is better access in this area than most that we map, so we’re thankful for that.  Only about two weeks left of the field season.  We’ll probably be jumping around a lot to work out problem areas on both quads during that time.

See you on the outcrop!

2014-03-26 009

Danny actually seeing through the groundcover to the rock beneath the Mountain Ranch golf course

 

 

 

 

 

STATEMAP Field Blog—August 19-21, 2013

Hello campers!

Well, much drier this week, but of course the heat is back!

We’re still working on the Shirley quad this week.  Started out Monday by dropping down a steep side drainage off Nubbin Ridge nearly to the Middle Fork, then right back up another one.  Got good points at the base of the Witts Springs and Cane Hill.  The Imo is at the bottom of the valley but the very large boulders eroding at the top cover most of it.  Relief was around 400 feet.

Tuesday and Wednesday we were back in the headwaters of Lost Creek.  There are many branches to this creek, and there seems to be a fairly large structure crossing them approximately east/west.  Could be a fault, or maybe just a fold of some kind—will take much more data collection to be sure.  We did observe a repeating sequence from higher elevations to lower—now we just have to figure out which formation they are in!  In the Ozarks, the Pennsylvanian-aged rocks are a series of sandstone and shale units deposited in a shallow marine environment.  That means they are all very similar to each other and the differences are subtle and vary from place to place.  To differentiate one formation from another, we depend a lot on context, which means we must take meticulous notes on each outcrop in the hopes we can see a pattern in the stratigraphy that matches something known.  We’re starting in the northwest corner of Shirley because we’ve already mapped the surrounding quads in that area, so have a pretty good idea of the geology there.  Things are getting more complicated as we reach the structure because the strata are displaced somewhat from one side to the other.  We will continue to add points next week in order to discover what the rocks are doing there.

ripple beds

ripple beds

Since I’ve mentioned some of the formations in the area and how difficult they are to differentiate, let me discuss one that has stayed fairly consistent across the Boston Mountains Plateau.  The Cane Hill is a Member of the Hale Formation, and its type section is in northwest Arkansas.  It is typically very thin- to thin-bedded, ripple-bedded, very fine-grained sandstone with interbedded shale and thicker shale units.  There are abundant trace fossils in the Cane Hill including asterosoma which is a somewhat star-shaped feeding burrow.

Trace Fossils:

Asterosoma:

concave solutioning in thin-bedded Cane HillBluffs of this sandstone often affected by a particular weathering phenomenon where the cement holding the sand together actually solutions out which lets the individual grains fall away eventually forming a concave structure.  I have included a good set of photos of the Cane Hill and a few of its characteristic structures.  It is getting to be over 300 feet thick as we continue to map toward the southeast.

See you next week!

Snake count: 2

Conostichus count: 1

Tick attacks: moderate to heavy