Volcanology

Since the European settlement of St. Eustatius in 1636 and Saba in about 1640 there has been no eruptive activity on either island. Westermann and Kiel (1961) regarded the domes on Saba as forming permanent seals to the volcanic conduits, which over time had led to a decrease and finally to the termination of the volcanic activity. The same authors considered that a ‘period of decadence and extinction of the Saba volcano’ had occurred in the middle of the Holocene, and that the younger Holocene showed only postvolcanic solfataric activity and the formation of the sulfur deposits. Further, Westermann and Kiel regarded a hot water spring north of Ladder Point to be the sole manifestation of the post-volcanic activity on the island. With regard to the Quill on St. Eustatius, the same authors considered the volcano, based on erroneous radiocarbon ages of corals from the Sugar Loaf, to be younger than 21,000 years and regarded the Quill as undergoing a final extinction between 5,000 and 3,000 years ago.
These conclusions regarding the eruptive history of Saba and the Quill, as well as the ages of the corals, are no longer supported by the results of the present stratigraphic studies on both islands. It is our view that due to the paucity of charcoal on both Saba, and in the younger
pyroclastic deposits of St. Eustatius, that our reconstruction of the youngest pyroclastic history of both volcanoes is probably fragmentary and incomplete. However the new data presented here are sufficient toindicate that Saba probably last erupted just prior to European settlement of the island, whereas the Quill was probably last active around 1,600-1,700 years B.P. Since there has been no long-term nor detailed monitoring of the islands, the only way of determining the present-day status of activity of the volcanoes is by studying the historic records for both
geothermal phenomena and felt seismic activity.
 
Obtained via the Saba Conservaton Foundation

The two small islands of Saba and St. Eustatius (Netherlands Antilles) lie on the northernmost subaerial end of the active arc of the Lesser Antilles. They are separated by the 28 km wide St. Eustatius Passage, and 20 km further along the arc the submarine Lumeyes Bank represents the northernmost volcanic center of the arc. Saba with an area of 13 sq. km rises to the single peak of Mt. Scenery at 877 m above sea level. The island is essentially a complex of andesitic Pelean domes with surrounding aprons of pyroclastic material.
In contrast, the island of St. Eustatius lies at the north end of a continuous submarine bank that also contains the islands of St. Kitts and Nevis. The island has an area of 21 sq. km and is morphologically dominated by two volcanic centers. At the northern end the extinct Northern Centers rise 289 m a.s.l. and were once a separate island surrounded by sea cliffs. Two and a half kilometers to the southeast the morphologically youthful Quill volcano, with an 800 m diameter open crater, rises to 600
m a.s.l. A third volcanic succession is exposed in the White Wall-Sugar Loaf tilted limestone succession, which forms the southern shoreline of the Quill. The Northern Centers comprise five morphologically distinct coalesced volcanoes, the most youthful of which is the Pisgah Hill-Little Mountain-Bergje Dome complex with a crater 880 m in diameter which contains the youthful Bergje dome. The Northern Centers comprises intercalated pyroclastic deposits (derived from Pelean activity) and lava flows.
 
Retrieved from Saba Conservation Foundation