Foliation measurements
194,290 foliation measurements from published US geologic maps, recorded as strike and dip and cited to the map each came from — 24% of the Atlas.
Show only foliation on the map
What it is
Foliation is a pervasive planar fabric in a deformed or metamorphosed rock: aligned micas, flattened grains, compositional banding, or the parting that alignment produces. Unlike bedding it is not a depositional surface — it is a strain feature, and it develops perpendicular to the direction of maximum shortening.
The term covers a family. Schistosity is coarse enough to see mineral flakes; gneissic banding is compositional segregation at a coarser scale still; in low-grade rocks the same fabric grades into cleavage. Published maps vary in how finely they split these, and the Atlas preserves the publisher's own term on every record card even where the type assigned here is the broader one.
Where foliation and bedding are both recorded at a station, the angle between them is the measurement that matters: it says where you are relative to a fold hinge.
How the Atlas records it
Every foliation row carries an azimuth and an inclination in one convention
(right-hand-rule strike and dip), a position in WGS 84 with the publisher's
own location confidence, the raw type term as the source published it, and the citation of the source map.
Selections export as CSV with a companion sources.csv of citations.
Which sources have it
| Source | Measurements | Share |
|---|---|---|
| NPS GRI parks | 40,410 | 21% |
| NGMDB legacy quads | 36,004 | 19% |
| USGS NGMDB GeMS | 30,939 | 16% |
| Washington Geol. Survey | 18,901 | 10% |
| USGS data releases · MRDS | 18,348 | 9% |
| USGS SIM quads (NE) | 11,571 | 6% |
| Vermont Geol. Survey | 10,506 | 5% |
| South Dakota SDGS | 5,370 | 3% |
| Alaska DGGS | 5,296 | 3% |
| Connecticut Geol. Survey | 5,165 | 3% |
| Wyoming WSGS | 4,515 | 2% |
| Idaho Geol. Survey | 2,716 | 1% |
| Montana MBMG | 1,492 | <1% |
| Maine Geol. Survey | 1,452 | <1% |
| Oregon DOGAMI (OGDC-8) | 842 | <1% |
| Pennsylvania Geol. Survey | 522 | <1% |
| Wisconsin WGNHS | 241 | <1% |
Where it is
| State | Measurements | Share |
|---|---|---|
| California | 31,931 | 16% |
| Colorado | 31,679 | 16% |
| Washington | 21,772 | 11% |
| Vermont | 14,003 | 7% |
| Wyoming | 9,773 | 5% |
| New Hampshire | 8,920 | 5% |
| Maine | 8,861 | 5% |
| Connecticut | 8,801 | 5% |
| North Carolina | 8,071 | 4% |
| Idaho | 7,924 | 4% |
| Alaska | 7,185 | 4% |
| Virginia | 6,913 | 4% |
| Montana | 5,436 | 3% |
| South Dakota | 5,416 | 3% |
| Nevada | 4,361 | 2% |
| Arizona | 2,721 | 1% |
| South Carolina | 2,291 | 1% |
| New York | 2,157 | 1% |
| Oregon | 1,319 | <1% |
| Minnesota | 1,287 | <1% |
| Georgia | 780 | <1% |
| New Mexico | 696 | <1% |
| Pennsylvania | 541 | <1% |
| Wisconsin | 241 | <1% |
| Maryland | 182 | <1% |
| New Jersey | 171 | <1% |
| Massachusetts | 133 | <1% |
| Missouri | 127 | <1% |
| Michigan | 122 | <1% |
| Utah | 62 | <1% |
| Rhode Island | 14 | <1% |
| District of Columbia | 14 | <1% |
| Tennessee | 4 | <1% |