Tag Archives: Tick Creek

Statemap Field Blog, Sept. 23-25, 2013

Hello all!

Another good week in the field!  Temperatures are getting low in the morning, but still warming up in the afternoon.  We started out by finishing up the rest of Tick Creek at the north edge of the map.  Got the lower Cane Hill sandstone up Files Hollow and again on the east side of Tick.2013-09-23 001  2013-09-23 014Still have good channel-bedded Imo below in the creek bed with a shale unit between the two.

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Tuesday and Wednesday we finished up the lower end of Indian Creek.  There were several massive-bedded sandstone units that had cut down into lower units of thin- to medium-bedded sandstone interbedded with shale.

This is probably all in the Witts Springs Formation, but we won’t know for sure until we see more of the rock in the area.  One of the indications that it is Witts Springs sandstone is the characteristic curved reentrant at creek level.  This is caused by exfoliation or spalling of curved sheets of rock due to more rapid dissolution of the calcareous cement near the creek.  The Witts Springs sandstone is typically more calcareous than overlying formations.    2013-09-24 0452013-09-24 060

You never know when you might see a classic example of a sedimentary structure while hiking around.  This week we saw some good examples of load casts in the creek float.  A sand deposit formed an irregular bulge as it pressed down (loaded) into the mud below.  Later lithification preserved the cast of that shape on the bottom of the sandstone bed.

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As we approached the southwest/northeast topographic lineation along the Middle Fork at the mouth of Indian Creek, we began to see more and more signs of a major structure.  Aside from a 5 to 7 degree southeast dip, there was an increasing abundance of deformation bands in the massive sandstone.   Also, we began to see a lot of non-vertical joints and small faults.  Took photos of a couple of fault planes with the slickensides still evident.2013-09-25 013  Slickensides are the parallel grooves or scratches left behind on the fault plane caused by the abrasion of one rock surface against another.  They are typically smooth in the direction of movement and rough in the opposite direction, so can indicate which way the fault moved.  Unfortunately there is no way to estimate throw, or the amount of offset on the fault, without knowing which formations are on either side.  That’s why we’ll have to be extra thorough in that area.  There’s probably a big fault somewhere along that lineation, but we’ve yet to find it so far.

By the way, Indian Creek must have gotten its name from the number of moccasins lying around.

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We’re taking a little hiatus next week so will be at least two weeks ’til the next installment.

See you on the outcrop!

Snake count: at least 4

Tick attacks: still severe

Statemap Field Blog, Sept. 8-13, 2013

Hello all!

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Silence of the cicadas

Signs that summer is almost over despite the continued warm temperatures include the silencing of cicada calls one at a time.  A welcome turn of events!

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More “crazy-bedding” in the upper Imo

This week was a long one because we worked in two different field areas.  On Monday and Tuesday we were back on Tick Creek looking at the last two major eastern drainages.  Found good Cane Hill/Imo contacts in each and a fairly consistent
irregular-, channel-bedded sandstone unit with abundant soft-sediment deformation near the top of the Imo.  It’s so irregular that I was calling it “crazy-bedded” before long. 

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“Crazy-bedding” in the upper Imo

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Yet more “crazy-bedding” in the upper Imo

There was also a section in the middle of the Cane Hill that was so perfectly cut by its east/west joint that it formed a smooth wall on the north side of the creek.  There was a parallel joint face on the south side, but it was not nearly as well exposed.

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Danny views joint face “wall” in Cane Hill

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Buttresses on Bear Creek

On Tuesday evening we joined Angela Chandler and Lea Nondorf, also of the Survey, on Bear Creek in Marshall to work on several other projects the rest of the week.  One ongoing project is to try to resolve edge-matching issues whenever we get a chance.  This involves gathering new data in boundary areas between quads that were mapped by different people or who used a different stratigraphy.  This week we were also looking for localities in the Imo interval for an upcoming field trip that Angela, Erin Smart and I are leading this spring for the GSA (Geological Society of America) conference in Fayetteville.  While looking at various road cuts, we also took new points on an area in the corner of four quads.  

Angela in front of lower Imo sandstone at the type section

Angela and Danny at the foot of the basal Witts Springs sandstone near Bryan Mountain

Wednesday and part of Thursday we looked at several possible field trip stops in the Imo, none of which seemed particularly suitable for one reason or another.  Mostly this is because the Imo doesn’t tend display good outcrops in this area due to its shaley composition and its typically being covered by the flaggy sandstone of the Cane Hill above.  We did visit the type section which is in Sulphur Springs Hollow to see if that could be used as a stop, but deemed the area too rugged unless a very small, sturdy group of geologists sign up.   A type section is an area where a formation or rock unit is first described and studied in detail.  In this case the type section was proposed then summarily  abandoned, but there are those working hard to see it reinstated eventually.

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Coalified wood prints in Imo sandstone at the type section

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Crinoids in red, fossiliferous Imo limestone at the type section

Another project that we are working on for the National Park Service is a compilation of all the quad maps along the Buffalo National River. Our agency and the US Geological Survey have each done about half of the quads in that area.  Most of the quads mapped by our agency did not include the higher terrace levels above the river–some as high as 200 feet!  This week we were able to get points on a few more of these terraces on the Snowball quad. 

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Smart Bluff above Arnold Bend on the Buffalo River

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Calcite fracture-fillings used as building stones in St. Joe

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Quartz crystal encrusted Boone chert used as building stones in St. Joe

We looked in Arnold Bend Thursday afternoon, and differentiated several terrace levels there, then on the way back to town, we stopped at a roadcut on Hwy. 65 that Angela knew about where there are quartz crystals growing in fractured Boone limestone and chert.  Danny had stopped at St. Joe on a previous field trip and so directed us there to see the quartz and calcite crystals encrusted on some of the old building stones in town.  These stones were no doubt found nearby along the several mineralized fault zones in the area.

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Early morning fog on Bear Creek

The next morning there was fog on Bear Creek and we headed up to Jamison Bluff to look for Plattin in the riverbed where it had been mapped previously.  This is part of the 6 mile section of the Buffalo between Woolum and Margaret White Bluff that dries up during the summer.  All we could find was St. Joe, so that part of the map remains as is. 

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Jamison Bluff along the Buffalo River

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River crossing at Woolum on the Buffalo River

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Looking down on Skull Bluff on the Buffalo River

 We crossed the Buffalo at Woolum and walked along the top of Skull Bluff to the Nars Cemetery most of which was covered with a terrace deposit (along with almost impenetrable black locust, cedar and briars).  

And of course, we couldn’t leave the area without a quick trip to “the Nars” itself for Danny and Lea to see for the first time.

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“The Nars”. Buffalo River left, Richland valley right.

“The Nars” is an almost sheer rock wall in the Boone formed as an erosional remnant between the valleys of the Buffalo River and Richland Creek.  Quite impressive as usual.  After that we had to get back to Little Rock and “the real world”.  See you next week.     

Tick attacks: severe

Statemap Field Blog, Sept. 3-5, 2013

Hello all!

Well, it warmed up again this week, but at least the humidity stayed lower.  Definitely getting a more golden quality to the sunlight in the evenings now, and the mornings are almost pleasant—maybe fall is just around the corner! 

Kinder Slough on Middle ForkSpent this week exploring lower Tick Creek which is one of the larger tributaries on the north side of the Middle Fork north of Shirley.  I can attest that this creek is aptly named.  It seemed that every plant above ankle high must be covered in them.  Danny and I mapped the upper end of this creek in the 2011-12 field season on the Fox quad.  It was all Cane Hill there with a cap of Witts Springs near the top.  This week we found Imo in the main channel a couple miles from its confluence with the Middle Fork, but haven’t found the contact with the Cane Hill yet.  Will look closer to the north edge of the map next week. 

Flood debris in lower Tick CreekAccording to local landowners, there was a 6-inch deluge at the end of May that washed out many of the access roads.  We could corroborate this after seeing all the large trees and other debris that had been piled up in the creek bed by the flood.  It looks like the entire valley may have been filled with water during that event.  Another good reason not to build anything in the floodplain of these steep-sided, narrow hollows in the Ozark uplands.  Where Still Hollow empties into Tick Creek, a small delta had developed during the flood event.Alluvial fan in Tick Creek 

There was also fresh cutting of the alluvial deposits along the stream bank which plainly showed a typical fining upward sequence.

 

Typical Cane Hill in small drainage to Middle ForkWe walked up quite a few side drainages along Middle Fork and Tick Creek to see if we could catch a glimpse of the Imo as it reaches the bottom of the Middle Fork valley, but the breakdown of the Cane Hill and Witts Springs above has covered it almost entirely.  That left us with thin-bedded Cane Hill sandstone as the lowest unit that produced a decent outcrop in these smaller branches. 

Slide block in creek bedMaybe we’ll get lucky when we hike up the sides of the Middle Fork north of this area.  We did see a large slide block that had fallen into the creek bed and was weathering away virtually intact.  If we had encountered that rock in isolation without the adjacent outcrop, we may have thought there was a fault close by due to the extreme inclination.  As it was, it’s just an interesting footnote to be filed away then used to cast aspersions on future structural theories based on similarly dipping rocks. 

 

What we did see of the Imo upstream in Tick Creek has a lot of interesting lithology (rounded siltstone concretions and coalified wood prints in shale) and bedding structures (soft sediment deformation).  Can’t wait to see what we’ll find upstream!

Snake count: 1

Tick attacks: severe