(Basic
Field Geology: GEOL 4120/6120)
(Advanced Field Geology: Geol
4121-6121)
| GEOLOGIC
MAP SYMBOLS |
| Qal | Quaternary alluvium (mapped only as the flat floodplain along modern rivers & streams) |
| Qp | Quaternary pediment surfaces and associated deposits |
| Qaf | Quaternary alluvial fan deposits (recognized by fan-shaped landforms) |
| Qls | Quaternary landslide deposits (recognized by scarp, hummocky land form and sharp toe; usually developed in Tertiary volcanics) |
| Qg | Quaternary glacial deposits undifferentiated |
| Qgl | glacial lacustrine (recognized by modern lakes and flat swampy modern meadows) |
| Qgt | glacial till - use dotted line to indicate position of moraines (recognized by erratic boulders and hummocky topography) |
| Qgo | glacial outwash (recognized by very flat surfaces or terraces above base level of modern streams) |
| Nv | Neogene volcanic rock undifferentiated (mostly 17 - 2 Ma); some of these are mapped separately, others are included in the Anderson Ranch Member of the Sixmile Creek Formation |
| Nvb | Neogene basalt, includes the 6.0 +/- 0.1 Ma Timber Hill basalt |
| Nvr | Rhyolite - mostly pyroclastic flow, fall and surge deposits |
| Ts | Tertiary (Neogene) Sixmile Creek Formation undifferentiated |
| Tsbh | Big Hole River Member |
| Tsa | Anderson Ranch Member |
| Tss | Sweetwater Creek Member |
| Tr | Tertiary (Paleogene) Renova Formation |
| Tdv | Tertiary Dillon Volcanics undifferentiated (Mostly Paleogene - 52-30 Ma) |
| Tdvb | basalt (Paleogene) |
| Tdva | andesite (Paleogene) |
| Tdvr | rhyolite, includes pyroclastic flow deposits and lava flows |
| KTb | Cretaceous/Tertiary Beaverhead Formation/Group. Contains limestone angular conglomerate/breccia in a red sandstone matrix, red sandstone and siltstone, quartzite cobble comglomerate with red sandstone |
| KTi | Late Cretaceous/Early Tertiary intrusive rock (70-140 Ma) associated with the Pioneer and Boulder Batholiths. Generally mapped by lithology, a - andesite, g - granite, r - rhyolite |
| Kcsc | Cretaceous Cold Spring Creek Volcanics (white & pink tuffs, dark fragmental volcanicbreccia) |
| Kf | Cretaceous Frontier Formation |
| Kb | Cretaceous Blackleaf Formation undifferentiated |
| Kbv | Upper volcaniclastic/shale member of the Blackleaf Fm (valley former) |
| Kblc | Lower clastic member (includes Kblsh & Kbuc of Dyman) of the Blackleaf Fm |
| Kk | Cretaceous Kootenai Formation undifferentiated |
| Kkg | Gastropod Limestone Member |
| Kksh | Upper Clastic (Shale) Member (valley former -- red shale with ribs of sandstone) |
| Kkm | Middle Limestone Member |
| Kklc or Kkss | Lower Clastic (Sandstone) Member (ribs of ss & congl. with red shale valleys) |
| Jm | Jurassic Morrison Formation |
| TR d | Triassic Dinwoody Formation - undifferentiated |
| TR du | upper bedded carbonate member |
| TR dl | lower shale member |
| Pp | Permian Phosphoria Formation (includes Mead Peak Phosphatic
Shale, Rex Chert, Park City Limestone, Retort Phosphatic Oil Shale, Shedhorn Sandstone) |
| IPq | Pennsylvanian/Permian Quadrant Sandstone (Quartzite) |
| MIPa | Mississippian/Pennsylvanian Amsden Formation |
| Mbs | Mississippian Big Snowy Formation/Group |
| Mm | Mississippian Madison Group undifferentiated |
| Mmm | Mission Canyon Limestone |
| Mml | Lodgepole Limestone |
| Dt | Devonian Three Forks Shale |
| Dj | Devonian Jefferson Dolomite |
| Ch | Cambrian Hasmark Dolomite |
| Cw | Cambrian Wolsey Shale |
| Cf | Cambrian Flathead Sandstone |
| pCu | Precambrian crystalline basement rocks undifferentiated. These are generally mapped using lowercase letters that designate lithologic units. g - granite, gn - gneiss, mg - mafic gneiss, m - marble, as - amphibolite schist, sh - schist, etc.; pick letters appropriate for rock type and area being mapped. |
Structural
Symbols
Normal contacts (black):
known location (+/- 10’)
approximate location (+/- 25’)
inferred location
Faults
(red):
Thrust
fault (teeth on upper plate)
Strike-slip
fault (show apparent motion in plane of map)
Normal
fault (show apparent motion) or ball on hanging wall
Folds
(blue):
Axial
trace of normal and overturned antiform or anticline
Axial
trace of normal and overturned synform or syncline
Strike
and Dip Symbols (black):
Strike and Dip of bedding (normal, vertical, overturned)
Strike and dip of foliation (normal and vertical)
strike and dip of joints (normal and vertical)
Colors:
All
geologic maps and structure sections should be colored. The colors should
be applied very lightly and evenly and should not obscure topographic
lines or other detail on the base map. Most mistakes in coloring are made
by applying colors that are too heavy or that are uneven. Following is
a list of some “standard” colors found on geologic maps. For
different formations of the same lithology, use different shades of the
same color group. Yellow should be reserved for Quaternary units. If only
one Quaternary unit is mapped it should be in yellow. If two are mapped,
Qal should be yellow and the other unit light orange.
Colors
by lithology:
surficial
deposits yellow (preferred) or light orange
sandstone
and conglomerate brown
shale,
siltstone & mudstone green
carbonates
blue
granitic
rocks red
volcanics
pink
basalt
pink or black
metamorphic
rocks use color appropriate for protolith
Colors
by Age:
Quaternary
yellow, pale yellow, white
Cenozoic
brown, orange, rust
Mesozoic
green, olive
Paleozoic
blue, purple
Precambrian
red, pink
