Harmony Hill Shale Member
Lithostratigraphy: Ottawa Limestone Megagroup >>Ancell Group >>Glenwood Formation >>Harmony Hill Shale Member
Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Champlainian Series >>Blackriveran Stage
Allostratigraphy: Tippecanoe Sequence
Primary source
Willman, H. B., Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, and Jack A. Simon, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p.
Contributing author(s)
H. B. Willman and T. C. Buschbach
Name
Original description
The Harmony Hill Shale Member of the Glenwood Formation (Templeton and Willman, 1963, p. 52).
Derivation
Named for Harmony Hill School.
Other names
In some areas in the Upper Mississippi Valley the Harmony Hill Shale Member is the only unit included in the Glenwood and is called the Glenwood Shale.
History/background
Type section
Type location
The type section of the Harmon Hill Shale Member is located 1 mile southeast of Harmony Hill School in a ravine 5 miles north of Grand Detour, Ogle County (W1/2 SE SE NE 24, 23N-9E), where the member is 5.9 feet thick.
Type author(s)
Type status
Reference section
Reference location
Reference author(s)
Reference status
Stratigraphic relationships
The Harmony Hill Shale Member is the uppermost member of the Glenwood Formation. The Harmony Hill is conformable, usually gradational, with the underlying members, but it locally rests unconformably on the St. Peter Sandstone. It is unconformably overlain by the Pecatonica Formation.
Extent and thickness
The Harmony Hill Shale Member is the most widely distributed member of the Glenwood Formation but is locally absent in the outcrop area and is generally absent in subsurface in northeastern Illinois. It is commonly 1-5 feet thick but has a maximum thickness of 27 feet in southwestern Ogle County.
Lithology
The Harmony Hill Member is a green, pyritic, finely laminated shale containing thin laminae of silt and very fine sand, but in places it becomes very sandy, and locally it is black. Phosphatic pellets are common near the top.
Core(s)
Photograph(s)
Contacts
Well log characteristics
Fossils
The Harmony Hill Shale Member contains a few fragments of scolecodonts, Lingula, and minute, dark red algae or spores.
Age and correlation
Environments of deposition
Economic importance
Remarks
References
TEMPLETON, J. S., and H. B. WILLMAN, 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.
ISGS Codes
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