Dundas Valley Conservation Area, Protected area in Ontario, Canada.

Dundas Valley Conservation Area is a protected area in Ontario, Canada, lying along the Niagara Escarpment and containing Carolinian forests, meadows, streams, and exposed rock formations. The terrain shifts between steep wooded slopes, open grasslands, and shallow waterways as you move through the valley.

The Dundas Valley began as a pre-glacial incision of the Niagara Escarpment; the Wisconsin Glaciation deepened it and left glacial and glaciolacustrine sediments that form today's kame and kettle hummocks. Post-glacial streams continued shaping the land. In 1834 Enerals Griffin, born enslaved in Virginia and escaped to Canada in 1828–29, bought the Griffin House and 50 acres; his family farmed there for 150 years.

The Hermitage was built in 1855 by George Gordon Browne Leith, a Scottish immigrant, using local clay bricks and limestone quarried in the Credit River valley. After a 1934 fire, Leith's daughter Alma Dick Lauder, a Hamilton Spectator writer, lived in a small house among the ruins until 1942. Wooden braces now stabilize the stone walls.

The 40-kilometre trail network starts at the Trail Centre, a replica Victorian railway station; the Main Loop Trail is a 3,420-metre loop from there. The Headwaters Trail, the longest at 10.5 kilometres, begins one kilometre along the Main Loop. Some trails cross into Ancaster, so carry a map to keep your bearings.

The valley sits at one of the northernmost edges where Carolinian forest can still be found, which is why it shelters species more commonly seen much farther south. This has contributed to the area being recognized as part of the UNESCO Niagara Escarpment Biosphere Reserve.