Guilford & East Haven: Agate Rockhounding in South Central Connecticut Planning Region, Connecticut

Plan your visit

Generally open to casual rockhounding

County

South Central Connecticut Planning Region

State

Connecticut

Nearest road

Towner Swamp Road

Postcode

06437

Coordinates

41.30202, -72.74609

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: Chaffinch Island Park (Guilford) offers free public parking and open shore access. Jacobs Beach and the East Haven town beach are resident-gated in season, with non-resident fees or permit requirements. As with all Connecticut beaches, there is no explicit public-trust right to remove rocks, so keep to light surface pebble picking below the high tide line.

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 Guilford & East Haven

Comfortable months (45 to 90°F highs)

Best months: March to November. Typical highs run 82°F in midsummer and 38°F in midwinter, with winter lows near 23°F.

Climate normals: NOAA 1991-2020 monthlies, NEW HAVEN TWEED AP station (8 mi away).

Geology at Guilford & East Haven

This spot sits on Waterford Group plus Stony Creek Granite Gneiss plus Narragansett Pier Granite, mapped as granite and gneiss that formed roughly 1000 to 250 million years ago. Plutonic rock like this weathers slowly into grus and boulders, and the most productive collecting is typically in weathered zones and drainages.

Mapped unit

Waterford Group plus Stony Creek Granite Gneiss plus Narragansett Pier Granite

Age

1000–250 Ma (Neoproterozoic to Permian)

Rock types

granite and gneiss

Elevation

110 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.

• Connecticut Geological Survey
• CT DEEP state land rules
• Community submissions reviewed against published agency rules