L4

Location   
36.415757,-94.219386 (Google Map)

Site name       
None
Type
Road cut (c.2005?) approximately 650 ft long

Age/Formation/Unit  (in stratigraphic order)

Mississippian / Boone

Features of interest
Vertical section of 20+ ft and one cut back terrace.  General lithology gray limestone and black, globular, glassy (choncoidal fracture) chert. Complex limestone/chert spatial relationships, including stranded limestone cores in chert nodules, sometime development of white chert crusts over black chert nodules, disrupted to non-existent bedding planes, and frequency fractured/infilled black chert nodules. Volume fraction of black chert estimated at 40%. Black chert sometime fractured with early mudrock infilling of cracks. Natural near-vertical fracture surface exposed bearing N150E.
Lithology present

Limestone, white chert, tripolitic chert
State/County    

AR / Benton County

Access         

US49 northbound exit and interchange to US71B southbound

Support material available

Photos (58 iPhone, 50 high resolution nikon with scale) partial photo montage. UArk MS theses: Paul Minor (2015). 

Site visit history

C. Liner 11/14/2012, 4/28/2013, 6/18/2013

Near-vertical fracture surface (light brown) bearing N150E.

Black chert nodule showing stranded limestone core and complex relationship to host limestone.

Heavily fractured black chert nodule with white chert crust and limestone mudrock infilling cracks. 

ImageJ analysis of outcrop photo. Grayscale threshold (red) identifies black chert volume fraction at 40%.