A fossil leaf deposit with particularly fine detail has been preserved in Dalton, located just 10 minutes north of Gunning. Research has dated this fossil back to the early Miocene era, around 21 million years ago, when a lava flow dammed the Lachlan River and created a lake over what is now Dalton. The fossil can be seen under the shelter in the park along Oolong Creek.
Dalton has long attracted the attention of geologists. Back in the late 1880s it was a thriving gold mining town, with reports that in 1879 ore crushing batteries were operating 24 hours a day.
The town is also famous for experiencing regular earth tremors as it is situated on a geologically active fault in the earth's crust.