Souris River: Quartz & Agate Rockhounding in McHenry County, North Dakota

Plan your visit

Generally open to casual rockhounding

County

McHenry County

State

North Dakota

Nearest road

River Road North

Coordinates

48.11499, -100.80194

Coordinates are approximate. Confirm the exact ground in the RockHoundR app, where land overlays show which agency manages the area.

Land & collecting status

Generally open to casual rockhounding

Most public-tagged spots sit on BLM, U.S. Forest Service, or other federal land where reasonable hand collecting of common rocks and minerals is allowed. Confirm posted rules and active mining claims before you dig.

Access note: Collect from public river accesses and gravel bars; the Souris River bed is privately owned (non-navigable), so get landowner permission off public parcels. J. Clark Salyer National Wildlife Refuge along the river is closed to rock and fossil collecting.

Public-land rules vary by agency, season, and field office. The RockHoundR app pulls live BLM, USFS, NPS, and tribal overlays so you can see exactly which agency manages the ground at this spot.

Best time to visit Souris River

Comfortable months (45 to 90°F highs)

Best months: April to October. Typical highs run 80°F in midsummer and 20°F in midwinter, with winter lows near -3°F.

Climate normals: NOAA 1991-2020 monthlies, VELVA station (7 mi away).

Geology at Souris River

This spot sits on Hell Creek Formation, mapped as sandstone, siltstone, and claystone that formed roughly 100 to 66 million years ago. Sedimentary layers like these are where fossils are typically preserved, and fresh exposures after rain or in active cuts tend to produce best.

Mapped unit

Hell Creek Formation

Age

100–66 Ma (Late Cretaceous)

Rock types

sandstone, siltstone, and claystone

Elevation

1,480 ft

Geologic mapping via Macrostrat and the underlying state geological survey maps (CC BY 4.0). Bedrock at the surface can vary within a mapped unit.

Sources & verification

Spot details combine the public RockHoundR location dataset, normalized mineral labels, agency land-status checks in the app, and community submissions. Coordinates are approximate until verified in the field.

• North Dakota Geological Survey
• Dakota Prairie Grasslands
• North Dakota Parks and Recreation rules
• Community submissions reviewed against published agency rules