II. Earth History - general concepts

A. Landscape development and age of Earth

1. static theory
1. Bishop Ussher - mid 1600s - Oct 4004 BC
2. dynamic theories
1. observations
• rocks form at volcanoes
• landscape affected by floods...
2. theories -(e.g. cooling, salinity)
• catastrophism - 1600-1700 - series of catastrophes
• uniformitarianism - late 1700s (Hutton), mid-1800s (Lyell):"present is the key to the past" although rates differ

1. Basic Principles
  - Steno
1. original horizontality (fig. 17.2)
2. lateral continuity
3. superposition
4. cross-cutting relationships (fig. 17.3) (Hutton)
2. Unconformities (fig. 17.7, 17.8, 17.9, 17.10)
1. disconformities
2. nonconformities
3. angular unconformities
3. Correlation
(figs. 17.13, 17.14, 17.16)
1. physical connection
2. unique minerals or fossils (fig. 17.6)
3. unique rock sequence
4. seismic data