  The gravitational production of superheavy dark matter, in the
Peebles-Vilenkin quintessential inflation model, is studied in two different
scenarios: When the particles, whose decay products reheat the universe after
the end of the inflationary period, are created gravitationally, and when are
produced via instant preheating. We show that the viability of both scenarios
requires that the mass of the superheavy dark matter to be approximately
between 10^{16} and 10^{17} GeV.
