American poet remembered for Shells, his 1999 debut poetry collection. He published Made Flesh, a second collection of poems, in 2008.
He studied at Yale University and at the University of Utah and subsequently taught literature at the University of Wyoming.
He disappeared in 2009 while hiking near a Japanese volcano.
He had a relationship with fellow poet Rebecca Lindenberg. Lindenberg's 2012 poetry collection, Love, an Index, deals with their relationship and with Arnold's disappearance.
He received the Amy Lowell Poetry Travelling Scholarship, as well as two National Endowment for the Arts Creative Writing Fellowships.