Final answer:
Jill Banfield's specific method for creating the tree of life is not stated; constructing a tree of life generally involves genetic analysis and molecular clocks to map species' evolutionary relationships.
Step-by-step explanation:
Jill Banfield is a geomicrobiologist and biogeochemist who contributed to understanding the microbial diversity on Earth, but a specific method attributed to her for creating the tree of life is not clearly stated in the information provided. The process of building a tree of life typically involves analyzing genetic material to establish relationships among different species and to map out evolutionary histories.
This biological data can be combined with the knowledge of molecular clocks and conserved proteins, like in the work of Hedges and colleagues, to infer key biological events and the timing of the origin of life in comparison to the age of the oldest fossils.