Monday, June 15, 2009

The Penultimate List of Map Units

It is crunch time on the map. I have so many other maps to work on that I need to begin seriously riding the asymptote to the completion of this one. After many years of solo and collective field observations and various consultations, arguments, and friendly exchanges with most of the Yeehows, I have settled on this list. If you have grave concerns please, please, oh please let me know sooner rather than later. I will throw the correlation diagram up soon.

Hillslope Deposits

Qcf Undivided colluvium and alluvial fan deposits, Holocene to Pleistocene

Qc Colluvium, undivided, Holocene to Pleistocene

Eolian Deposits

Qe Eolian sediments, Holocene to late Pleistocene(?)

Deposits of the Owyhee River

Qra Active channel and floodplain alluvium, Recent to late Holocene

Qry Young fluvial sediments, Holocene

Qrty Young floodplain terraces, Holocene

Qrt1-n Fluvial terrace gravels, Pleistocene (numbered in local depositional order where appropriate)

Qrg Fluvial gravel, undivided, Pleistocene

Qgb Fluvial boulder bars, Pleistocene

Qgw Fluvial gravel of West Crater lava, late Pleistocene

Qrgo Older fluvial gravel, Pleistocene

Qgbr Fluvial gravels of Bogus Rim lava, early Pleistocene

QTgl Ancient, inter-lava flow fluvial gravel, early Pleistocene to Pliocene

QTga Fluvial gravel of Artillery rim, early Pleistocene to Pliocene(?)

Lacustrine deposits of the Owyhee River corridor

Qfl Fluvio-lacustrine sediments, undivided, late Pleistocene

Qflw Fluvio-lacustrine sediments of West Crater lava dam, late Pleistocene

Qfls Fluvio-lacustrine sediments of Saddle Butte lava dam, late Pleistocene

QTfa Fluvio-lacustrine sediments of Artillery Rim, early Pleistocene to Pliocene

Landslide Deposits

Qls Landslide deposits, undivided, Holocene to early(?) Pleistocene

Qlsy Young landslide deposits, Holocene to late Pleistocene

Qlsby Young landslide deposits composed dominantly of coarse basalt breccia, Holocene to late Pleistocene

Qlsi Intermediate age landslide deposits, late Pleistocene

Qlso Old landslide deposits, middle to early (?) Pleistocene

Alluvium of Owyhee River tributaries and local drainages

Qa Alluvium of tributary washes and alluvial fans, undivided, Holocene to Pleistocene

Qas Alluvium and related sediments of active springs, Holocene to late Pleistocene

Qad Alluvium of closed depressions and sags, Holocene to late Pleistocene

Qay Young alluvium of tributary washes and alluvial fans, Recent to Holocene

Qai Intermediate age alluvium of tributary washes and alluvial fans, late Pleistocene

Qao Old alluvium of tributary washes and alluvial fans, middle to early Pleistocene

QTa Ancient alluvium of tributary washes and alluvial fans, early Pleistocene to Pliocene

Basalt lavas of the Owyhee River corridor and surrounding areas

Qbcp Basalt of Coffee Pot Crater, Holocene*

Qbrb Basalt of Rocky Butte, Holocene (?) to late Pleistocene*

Qbw Basalt of West Crater, Pleistocene

Qbs Basalt of Saddle Butte

Qbsy Younger basalt of Saddle Butte

Qbso Older basalt of Saddle Butte

Qbc Basalt of Clarks Butte

Qbg Basalt of Greely bar, early Pleistocene

Qbr Basalt of Bogus Rim, early Pleistocene

QTbc Basalt of Bogus cliffs, early Pleistocene to Pliocene

QTb Basalt, undivided, early Pleistocene to Pliocene

Tb Undivided basalt lavas, Pliocene to Miocene (?)

Tbs Undivided basalt lavas and interbedded sediments, Miocene to Pliocene

*These lavas only on regional map, not in river corridor

Rhyolite lavas and sedimentary rocks

Tsv Interbedded volcanic, volcaniclastic, and other sedimentary rocks, Miocene

Tr Undifferentiated rhyolite lavas, Miocene


  1. Senor Jerque,

    Can you elaborate on the differences between the Qgbr, the QTga, and the QTfa? I may have not been privy to the latest discussion, but it seems to me that these deposits may all relate to the filling and emptying of a lake behind a BR lava dam. I can see that Qgbr (b/t Iron Pt. and Jackson Hole are coarser and may record the breaching of a dam, but how are QTga and QTfa difference from eachother?

  2. Thanks for commenting!

    Here is the concept. The Qgbr refers to the pods of gravel on top of the Bogus Rim lava that are strongly biased toward basalt and rhyolite. The QTga is the sanctified rim gravel. There is enough of that gravel in enough places to make me cautious about assigning it to only the Bogus Rim lava dam. Possible that the lower Bogus also dammed the river (pretty clearly in places with PPCs/ PPB) and I don't know if that unit is Pliocene or Pleistocene yet. The QTfa refers to areas (as yet unmapped) that contain large exposures of lacustrine mud with lesser amounts of gravel. Some good examples off of the road that passes Owyhee Butte. Also some screaming examples on the road to Arock. QTfl would be a better name.

    Btw: I officially trod upon your upstream most deposit of gravel on the Qbw last week.

  3. Ah, yes, I did forget the potential for lower Bogus dams and related sediment.

    Glad you found the gravel on Qbw. Did you work more on resolving the depocenter/kipuka problem in the middle of the WC?

  4. Could not tear away from field camp to check out the other West Crater issues.

    The depocenter (augerville) will be the site of next year's augering competition. I may stroll through there in July or August.


Note: Only a member of this blog may post a comment.