The Devonian, terrestrial Eden Rhyolite attains a thickness of 156 m and in stratigraphic order consists of the following units: Flow Two followed Flow One rapidly enough to form one cooling unit and these two flows represent the bulk of the Eden Rhyolite sequence. The sources of these acidic eruptions were probably north-south trending fissures formed in an elongated, terrestrial foredeep in front of an orogen toward the west.