left to right: 
(front two rows) -- David, Alex, Marc, Emily, Justin, Ruth, Zoe, Virginia, Cory, Judith, Sarah, Heather, Erin, Liz, Laurie, Frances, and Jon.

(back row standing on a rock) -- Geert, Matt, Gus, Tecumseh, and Ricardo

left side of the table:
Katharine, Virginia, Alberto, Judith, Altay, and others

right side of the table:
Marc, Cory, Roian, Sarah, Joanna, and others