The scientist and explorer Alexander Agassiz built a summerhouse here in 1874, concluding that Newport provided an excellent environment to study marine animals. The home was outfitted with a research laboratory where students and guests came here to study until its function was replaced by the Marine Biological Laboratory at Woods Hole, MA.
Here, Agassiz also worked in his extensive gardens, played golf and entertained. He deeded his land to the government for a lighthouse, which was first used in 1890. His family remained on Castle Hill until the Hurricane of 1938, when the peninsula was temporarily cut off from the mainland.
This sequence consists of upward fining, graded maroon and green turbidites with interbedded, finely laminated gray and maroon siltstones, and maroon and green slate, that are characteristic of the Castle Hill member. It is followed by dominantly pale to dark green chloritic siltstones, maroon siltstones and slaty, gray to white weathering porcellanitic tuffs, and minor finely layered gray to greenish siltstones and phyllite of the graves Point member. Both members included in the traverse contain sills and dikes of highly altered, bright green mafic rock.