Final answer:
An oasis is created in a desert when water from an underground aquifer surfaces naturally, providing a fertile area in a typically dry environment.
Step-by-step explanation:
A oasis is formed when water from a confined aquifer discharges through fractures in the desert. Unlike a geyser, which involves the dramatic eruption of steam and hot water as a display of thermodynamic principles due to heating by magma, an oasis forms when underground water reaches the surface naturally, often creating a fertile area in an otherwise arid environment.
Oases can support both vegetation and wildlife and have been crucial for human settlements in desert regions.