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National Geologic Map Database
Geologic Unit: Saypo
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Map showing publication footprint
  • Usage in publication:
    • Saypo limestone member
  • Modifications:
    • Original reference
  • Dominant lithology:
    • Limestone
  • AAPG geologic province:
    • Montana folded belt
Publication:

Deiss, C.F., 1933, Paleozoic formations of northwestern Montana: Montana Bureau of Mines and Geology Memoir, no. 6, 51 p.


Summary:

Pg. 46+. Saypo limestone member of Madison limestone. In lower part of Madison limestone. Thickness 72 to 141 feet. Lower 91 feet is shaly fine-grained argillaceous limestones interbedded with white smooth and thicker-bedded argillaceous limestones; weathers bright buff. Overlying 20 feet is massive thick-bedded gray crinoidal limestones that weather gray. Upper 30 feet is massive chocolate-colored crinoidal limestones, thick-bedded in upper part and thinner-bedded in lower part. In Pentagon Mountain area the very top of the Saypo is a thin zone of shaly thin-bedded tan limestone crowded with poorly preserved fenestellid BRYOZOA. Underlies Dean Lake chert member and overlies Silvertip conglomerate, basal member of Madison. Age is Mississippian.
Type locality: on south side of upper part of Pentagon Mountain, in SW/4 sec. 14, T. 25 N., R. 12 W., [Pentagon Mountain 7.5-min quadrangle, Flathead Co.], northwestern MT, where it forms a buff-colored, relatively gentle slope beneath the harder Dean Lake chert. Named from Saypo quadrangle, over much of which it is well exposed.

Source: US geologic names lexicon (USGS Bull. 896, p. 1938).


Map showing publication footprint
  • Usage in publication:
    • Saypo limestone
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Montana folded belt
    • Sweetgrass arch
Publication:

Weller, J.M. (chairman), Williams, J. Steele, Bell, W.A., Dunbar, C.O., Laudon, L.R., Moore, R.C., Stockdale, P.B., Warren, P.S., Caster, K.E., Cooper, C.L., Willard, Bradford, Croneis, C.G., Malott, C.A., Price, P.H., and Sutton, A.H., 1948, Correlation of the Mississippian formations of North America: Geological Society of America Bulletin, v. 59, no. 2, p. 91-198.


Summary:

Pl. 2 (column 38). Saypo limestone in Hannan limestone. Shown on correlation chart as the lowermost unit in Hannan limestone. Underlies Dean Lake chert. Age is Early Mississippian (Kinderhook).

Source: US geologic names lexicon (USGS Bull. 1200, p. 3487-3488).


Map showing publication footprint
  • Usage in publication:
    • Saypo limestone
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Montana folded belt
Publication:

Andrichuk, J.M., 1955, Carboniferous stratigraphy in mountains of northwestern Montana and southwestern Alberta, IN Lewis, P.J., ed., Sweetgrass arch-Disturbed belt, Montana: Billings Geological Society Guidebook, September 7-9, 1955, no. 6, p. 85-95.


Summary:

Pg. 89. Saypo limestone. [Considered a formation.] Assignment of group status to the Madison of northwestern Montana precludes any need for term Hannan. [= part of Sloss and Laird's MC unit. Age is Early Mississippian (Kinderhook).]

Source: US geologic names lexicon (USGS Bull. 1200, p. 3487-3488).


Map showing publication footprint
  • Usage in publication:
    • Saypo Limestone Member
  • Modifications:
    • Not used
  • AAPG geologic province:
    • Montana folded belt
    • Sweetgrass arch
Publication:

Mudge, M.R., Sando, W.J., and Dutro, J.T., Jr., 1962, Mississippian rocks of the Sun River Canyon area, Sawtooth Range, Montana: American Association of Petroleum Geologists Bulletin, v. 46, no. 11, p. 2003-2018. [Available online, with subscription, from AAPG archives: http://www.aapg.org/datasystems or http://search.datapages.com]


Summary:

Pg. 2009, 2012. Deiss' Saypo Limestone Member of Madison Limestone is essentially = to the lower member of Allan Mountain Limestone (new). Type section of the lower member is [within the Saypo quadrangle, scale 1:125,000], on ridge north of Gibson Reservoir, east of the SE corner of sec. 36, T. 22 N., R. 10 W., Patricks Basin 7.5-min quadrangle, [Teton County], northwestern Montana.

Source: Publication.


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For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).

Slash (/) indicates name does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).