Hawksbill Station
Robert Silverberg
 Hawksbill Station is a penal colony in the pre-Cambrian era created by the authoritarian United States government, using time travel as a means to exile rebels and political dissidents into the past. The colony houses only male exiles (a female settlement supposedly exists later in the Silurian era), who are sent there as a "humane" alternative to execution. The machine only works one way, so the prisoners are hopelessly marooned in the past. The distant prison is in a barren coastal area prior to the colonization of land by sophisticated life, and evokes a Tsarist Siberia or a Soviet Gulag. The personal relationship of the main character, the de facto leader of the colony, and both his government torturer/prosecutor and Dr. Hawksbill, each of whom had been members of the dissidence movement, as well as explication of the picayune ideological differences among the prisoners, and the confused circumstances leading to the establishment of the authoritarian government, further parallel Russian history. As the novel opens, the prisoners, all of them middle-aged or elderly, are surprised by the arrival via the time machine of a much younger prisoner. Their surprise increases when they question the newcomer, ostensibly an economist, about economic theory and political ideology, and his answers reveal his essential ignorance of either. His ignorance and youth cause the prisoners to wonder if he is fact a political prisoner at all or a "common" criminal who would only have been exiled for a heinous crime. When the newcomer arrives via the Hawksbill time machine a second time, it is revealed that he is a police officer of a new government which overthrew the authoritarian regime but was unrelated to the dissident movements of which the Hawksbill exiles were members; upon the overthrow, the new government discovered both the existence of Hawksbill Station and that means had been discovered to effect time travel from past to future, making it possible to retrieve prisoners from the colony. The newcomer has been sent to evaluate the prisoners and to recommend whether they are mentally stable for retrieval. With return now possible, the leader of the exiles realizes that he is a time traveler of a different sort: the struggle against the authoritarian regime, his life's work, is over; his closest friends in the movement (and his bitterest enemies, who left the movement to join the authoritarian government) are irretrievably dead; and even those who finally did overthrow the government have little connection with or regard for his brand of dissent (as demonstrated by the newcomer's ignorance of their ideologies). He is now somewhat inclined to visit the newcomer's future, but staying at Hawksbill Station is now the only existence he knows.