Together, the formation was affected by low-grade metamorphism and primary minerals such as pyroxene, plagioclase and hornblende altered to prehnite, pumpellyite and zeolite.
It contains Maastrichtian Late Cretaceous shallow water fossils such as foraminifera, algae, gastropods, bivalves and rudists.
The Paleocene Soebi Blanco Formation is a 400-meter thick sequence of conglomerates, sandstones and mudstones at Seroe Largo in central Bonaire.
It is similar to the Midden Curacao Formation in that it contains fragments of exotic rock not found in the area, such as quartzite, gneiss and schist.
Uranium-lead dating gives an age of 1.15 billion years old on zircon fragments within a granulite pebble from the formation, suggesting that it is eroded material from much older rock in South America.