Slickenline measurements
1,623 slickenline measurements from published US geologic maps, recorded as trend and plunge and cited to the map each came from — <1% of the Atlas.
Show only slickenline on the map
What it is
Slickenlines are the grooves, ridges and mineral fibres scored into a fault surface as the two sides moved past each other. They are recorded as a trend and plunge lying within the fault plane, and they answer the question the plane alone cannot: which direction the slip was.
A fault plane plus a slickenline — a fault-slip datum — is the unit of data for paleostress inversion and for kinematic analysis of a fault population. Where the published record also gives a sense of shear, the datum is fully determined.
Read the source record before using these. "Striation" in the published literature is not always tectonic: glacial striae on a bedrock surface are recorded with much the same field vocabulary and, in glaciated terrain, are numerically common in this compilation. The Atlas preserves the publisher's own term and citation on every row precisely so that this distinction stays checkable rather than being flattened at compile time.
How the Atlas records it
Every slickenline row carries an azimuth and an inclination in one convention
(trend and plunge), 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 |
|---|---|---|
| USGS data releases · MRDS | 529 | 33% |
| USGS NGMDB GeMS | 342 | 21% |
| NPS GRI parks | 243 | 15% |
| NGMDB legacy quads | 223 | 14% |
| USGS SIM quads (NE) | 199 | 12% |
| Alaska DGGS | 80 | 5% |
| Pennsylvania Geol. Survey | 4 | <1% |
| Oregon DOGAMI (OGDC-8) | 3 | <1% |
Where it is
| State | Measurements | Share |
|---|---|---|
| California | 541 | 33% |
| New Hampshire | 180 | 11% |
| Montana | 163 | 10% |
| Pennsylvania | 133 | 8% |
| Alaska | 129 | 8% |
| North Carolina | 110 | 7% |
| Arizona | 94 | 6% |
| Virginia | 87 | 5% |
| Vermont | 49 | 3% |
| New Mexico | 34 | 2% |
| Washington | 23 | 1% |
| New Jersey | 19 | 1% |
| Colorado | 17 | 1% |
| Idaho | 13 | <1% |
| Oregon | 11 | <1% |
| New York | 10 | <1% |
| Georgia | 6 | <1% |
| Maine | 2 | <1% |
| Minnesota | 2 | <1% |