Ancient Shores
Jack McDevitt
 The vast lake, Lake Agassiz, covered much of North Dakota, Manitoba and Minnesota during prehistoric times. The story begins when farmer Tom Lasker and his son, Will, uncover a seemingly brand new yacht. Found on a landlocked farm, it draws tourists to the area. Max Collingswood, a friend of Tom's, tries to help discover the origins of the boat. Collingswood enlists April Cannon, a worker at a chemical lab who discovers that the yacht is made of an unknown material. In fact, it is a fiberglass-like material with an impossible atomic number (161). Collingswood and Cannon discover something else on a nearby ridge which is part of a Sioux reservation. The Sioux assist in its excavation and examination. It turns out to a green glassy roundhouse-like structure, made from the same material. Eventually, they gain access to it, revealing a dock for the sailboat, but no entrance for it. The discovery that the structure contains the means to access other sites not on Earth sets off a struggle between the Government and the Reservation for control of it.