Tag Archives: Atoka

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

Advertisements

Statemap Field Blog, Dec 16-18, 2013

2013-12-17 001

Hello all!

Well, it’s been a week and a half since the snow came down, and there are plenty of shady areas where it’s still on the ground.  We started out on the east side of the map in Deadland Hollow, even though it was north-facing, because we knew we could get to it fairly easily.  If anything, the snowy areas may even have been a little more treacherous this week, because it’s thawed and frozen so many times that it’s more like solid ice now.  After that we went all the way over to the west side of the map and got a few points in a small drainage south of Weaver Creek.

2013-12-16 001

On Tuesday we walked from the lake to the top of Dave Creek in an undeveloped part of Fairfield Bay.  Saw some really good worm burrows in a thin- to medium-bedded sandstone  near where the creek reaches the lake.  Some of these burrows crossed bedding planes, so the rate of sedimentation must have been fairly rapid during deposition of this unit.  2013-12-17 0102013-12-17 030

Above that, we were in fairly continuous outcrops of calcareous sandstone, including some beds of “zebra rock” (see previous two posts).  We can only surmise that we are again in the Witts Springs Formation, which is interesting in that it’s still at the surface south of that Weaver Creek/Middle Fork lineation.  This probably means that if the lineation formed due to a fault at the surface, there is minimal offset.  More likely, it indicates the lineation formed along a monocline at the surface perhaps indicating a fault at depth in the basement rock.  Anyway, we had several hundred feet of calcareous sandstone along the creek, some of which exhibited large scale cross-bedding.

2013-12-17 0392013-12-17 045

We’re still working on that Bloyd/Witts Springs contact, but probably did cross it somewhere in that upper end.  There may even be some Atoka up there, but if so, it will be in sparse exposures at the very highest elevations.  If the Bloyd proves to be several hundred feet thick here as it has been on other quads to the west, the only Atoka may be on the southern third of the Fairfield Bay quad south of the southwest/northeast lineation that goes through the upper end of Greers Ferry Lake.  This is almost undoubtedly a fault at the surface based on the steep dips we’ve been seeing on the north edge of the lake.

On Wednesday, we started at the lake again and went up a small drainage on the eastern edge of the map.  Had a great view of Sugar Loaf Mountain when we started that morning.

2013-12-18 001

Well, I hate to say it, but this will be the final blog of this field season.  I have a major test and a GSA field trip to prepare for this spring, so I need to devote all my time to that right now.  It’s been fun to write it, and I hope I’ve given you a better idea of what range of effort goes into making a “simple” geologic map.  We’ll keep going out until mid-April, then we’ll have about 10 weeks in the office to draw and digitize the two maps, add descriptions of the rock units, a cross section, stratigraphic column, joint diagram, and correlation of map units.  If all goes according to plan, we’ll turn the finished maps into the USGS on June 30 to fulfill our grant requirements.  The Shirley and the Fairfield Bay quads should be up on our website as a .pdf by mid-July.  By that time, we’ll be back in the field battling ticks and snakes next season–probably on the Parma and Greers Ferry quads.  Who knows, maybe I’ll start blogging again!  Until then, see you on the outcrop!