Geological history of Dominica
1. Eruptions first occurred around Morne Concorde, Morne Fraser, and Morne au Delices — these have left the oldest exposed volcanic rocks along the windward coast and are estimated to be about 13-25 million years old.
2. Next recorded is Morne Couronne which was thrust up between 1-12 million years ago.
3. The next to be formed were the highlands from Morne Anglais through Watt Mountain to the Freshwater lake.
4. Within the last one million years Morne Negres Marrons grew up beside Morne Couronne.
5.Eruptions centered on the Foundland Peak built up the southeast corner about the same time.
6. Early magma from Trois Pitons formed coastal areas from Mahaut to Loubiere.
7. Early magma from Diablotin produced the remaining coastline northward to Barbers Block.
8. Plat Pays center was the next to erupt.
9. Morne Anglais produced an adjacent fall of pyroclastics (solid fragments ejected by volcanoes).
10. Eruptions centered on Morne au Diable less than half a million years ago piled up the northern headland of Dominica.
11. The peak of Micotrin was formed and produced the flows that cover the Roseau valley.
12. Trois pitons erupted again, forming the present enormous land mass.
13. Ash covered the Mang Peak area.
14. Morne Diablotin erupted and produced a gigantic ash flow.
15. Morne Patate has been the last to be formed, of which a partially weathered crater remains today, and from which steam explosions showered Roseau with dust in 1880.

(Source of map and geological history information: "Geology and Soils," by P. Narodny Honychurch)