This week we discuss the geologic time scale, meteorites, and fitness trackers!
Pittsburgh Fireball Feb. 17, 2015
- Video of meteor
- Article with details of entry
- Animation from meteor’s perspective
- NASA Fireball Network
Geologic Time-it’s really big (and deep)
- The geologic time scale
- Despite all kinds of fun things to demo how vast it is…still hard to understand
- Cosmic Calendar
- Pneumonic devices for timescale-and why do we need to know it? (several examples)
- We make all kinds of assumptions about rocks that span millions of years, but an outcrop can change over the course of just a few years/ten years
- Example of things changing in days to hours
- Time’s Arrow, Time’s Cycle
How do we begin to define Geologic time?
- International Commission on Stratigraphy: “ International Geologic Time Scale; thus setting global standards for the fundamental scale for expressing the history of the Earth”
- We have to have a baseline so that we can all talk about the “same” rocks across the world
Age-dating rocks
- Many techniques, and the actual dates between our epochs change all the time as our age-dating techniques evolve
- Many periods/eras/epochs are marked by “catastrophic” occurrences, hence making them natural boundaries, but the dates change.
- 5 major extinction events
Time as an arrow v. time as a cycle
- Catastrophism vs. uniformitarianism and gradualism
- Constantly evolving and vastly interesting
- Thinking about the definitions of time and how we as humans try to grasp the enormity of geologic time in particular is humbling.
Fun Paper Friday
- In an attempt to prolong our time on Earth, we’ll talk about accuracy of fitness apps. (John wears a Fitbit Flex and uses the Fitbit Aria scale.)
- “Accuracy of Smartphone Applications and Wearable Devices for Tracking Physical Activity Data”, Case et al., Feb 2015, Journal of the American Medical Association