Vein / dike measurements
20,175 vein / dike measurements from published US geologic maps, recorded as strike and dip and cited to the map each came from — 2% of the Atlas.
Show only vein / dike on the map
What it is
Veins and dikes are recorded together because they are the same structural object measured the same way: a tabular fill occupying a fracture that opened. The difference is what filled it — mineral precipitate from a fluid in a vein, magma in a dike.
Because a fill of this kind requires the fracture to have opened rather than sheared, its orientation is a direct record of the least principal stress at the time: a dilational fracture opens perpendicular to it. A swarm of dikes with a consistent strike is one of the more reliable regional stress indicators available from a map.
Veins are also the structure most likely to be measured selectively — recorded where they were economically or petrologically interesting and passed over where they were not — so density on the map should not be read as density in the ground.
How the Atlas records it
Every vein / dike 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 |
|---|---|---|
| USGS data releases · MRDS | 15,659 | 78% |
| NPS GRI parks | 1,254 | 6% |
| USGS NGMDB GeMS | 1,208 | 6% |
| USGS SIM quads (NE) | 617 | 3% |
| South Dakota SDGS | 468 | 2% |
| NGMDB legacy quads | 460 | 2% |
| Washington Geol. Survey | 275 | 1% |
| Alaska DGGS | 229 | 1% |
| Idaho Geol. Survey | 3 | <1% |
| Pennsylvania Geol. Survey | 1 | <1% |
| Wyoming WSGS | 1 | <1% |
Where it is
| State | Measurements | Share |
|---|---|---|
| California | 3,685 | 18% |
| Utah | 2,255 | 11% |
| Nevada | 1,624 | 8% |
| Idaho | 1,448 | 7% |
| Arizona | 1,399 | 7% |
| Montana | 1,033 | 5% |
| Alaska | 1,002 | 5% |
| Colorado | 820 | 4% |
| Oregon | 742 | 4% |
| South Dakota | 712 | 4% |
| Maine | 697 | 3% |
| Washington | 663 | 3% |
| Virginia | 625 | 3% |
| North Carolina | 572 | 3% |
| New Mexico | 493 | 2% |
| New Hampshire | 425 | 2% |
| Vermont | 394 | 2% |
| New York | 271 | 1% |
| Wyoming | 162 | <1% |
| Tennessee | 126 | <1% |
| New Jersey | 97 | <1% |
| Texas | 90 | <1% |
| Alabama | 83 | <1% |
| Minnesota | 59 | <1% |
| Oklahoma | 50 | <1% |
| Kentucky | 46 | <1% |
| South Carolina | 46 | <1% |
| Michigan | 30 | <1% |
| Pennsylvania | 29 | <1% |
| Arkansas | 19 | <1% |
| Illinois | 18 | <1% |
| Missouri | 17 | <1% |
| Georgia | 10 | <1% |
| Puerto Rico | 9 | <1% |
| Connecticut | 8 | <1% |
| Wisconsin | 6 | <1% |
| Maryland | 6 | <1% |
| Indiana | 4 | <1% |
| Massachusetts | 2 | <1% |
| Florida | 2 | <1% |