From the results of this preliminary survey it would appear that the bathyliths of the southern belt of the Tasman Geosyncline represent a history of continuous tectonic activity from Middle Silurian through to Middle Devonian, with a gradual movement eastwards of the axis of the intrusions. The gneissic “Ordovician‐type” granite is dominant in the Upper Silurian, just preceding the foliated “Silurian‐type” plus massive types which are dominant in the Lower Devonian, but with significant overlap in time between them to the extent that “rock type” is not a safe determinant of age. It is therefore recommended that this terminology be no longer used. A few cases of Carboniferous intrusion have been observed. These generally are transgressive to the main trend. Later intrusions occurred to the east and north, ranging from Permian in New England to Mesozoic further north, in good agreement with expectation. Smaller Mesozoic instrusions in the southern coastal region have ages different from those anticipated.