Due: 10/2/08 Geology 1002.1 Project 3

A METAPHOR FOR GEOLOGIC TIME

In order to put the geologic time scale into human terms, you are going to translate the last 4.6 billion years of earth history into your life span.

Information required:

1) Date and Time of your birth (make something up if you don't want to use your real birth date)

2) Date and Time that the assignment is due: October 2nd, 2008 at 9:10 AM

3) Geologic/Historical dates to be translated:

Age of Earth - 4.6 billion years Flowering Plants – 125 million years Oldest rocks - 4.0 billion years Extinction of Dinosaurs - 65 million years Oxygen rich atmosphere - 2.7 billion years First Hominids - 5 million years Multicellular life - 542 million years Modern Humans - 120 thousand years Formation of Pangaea - 237 million years Great Pyramid of Giza – 4.5 thousand years

How to do calculations:

1) Compute how many days in your life using 365.25 days in a year and 30.5 days in a month.

2) Compute the fraction of earth's history represented by each date. For example, the oldest rocks formed 0.1304 (or 13.04%) into Earth's history

0.1304 = (4.6 billion years - 4.0 billion years)/4.6 billion years

3) Multiply the fraction of earth's history times the number of days you have been alive. Next add those days to your birth date to get the date of that event in terms of your life span. Convert days to years and months by assuming 365.25 days a year and 30.5 days a month. You will get the most accurate result if you truncate conversions to the nearest day.

4) For geologic events the date is all that is necessary, for the historical event please give the date and the time (24 hours in a day and 60 minutes in an hour).

A Partial Example (my daughter Melanie who is 26):

Melanie's Birthday - 1/16/82 at 06:32 AM Date Assignment Due - 10/2/08 at 9:10 AM

On 10/2/08, Melanie will be 9756 days and 2 hours and 38 minutes old

26 years times 365.25 days = 9496.5 or 9496 days 8 months times 30.5 days = or 244 days

9496 + 244 + 16 = 9756 days 2 hours and 38 minutes = 0.11 of one day 9756.11 days

Earth's oldest rocks formed 1272.11 days into Melanie's life

0.1304*9756.11 = 1272.54

This is 3 years, 5 months, 24 days, 6 hours and 58 minutes after Melanie was born

1272.54/365.25 = 3.484 years

1272.54– 3*365.25 (1095) = 176.79 days

176.79/30.5 = 5.796 months

176.79 – 5*30.5 (152.5) = 24.29 days

(24.29 -24)*24 = 6.96 hours

(6.96 – 6)*60 = 58 minutes

add 3 years to 1982 and it is 1985

add 5 month to January and it is June

add 24 days to the 16th of June and it is the 10th of July

add 6 hours to 6 AM and it is 12 AM on 10th of July

Add 58 minutes to 32 and it is 1:30 PM

So in the Melanie time scale the Earth’s oldest rocks formed on July 10th, 1985 at 1:30 PM

Information to Turn In (Please show all work in calculations):

1. Data in tabular form

Melanie's Birthday 1/16/1982 06:32

Today 10/2/2008 9:10

Days in life 9756.11

Geologic Event Time Ago Fraction Elapsed Days of Date and Time Earth's Age your life Formation of Earth 4.6 b.y. 0 0 1/16/82 6:32 AM Oldest Rocks 4.0 b.y. 0.1304 1272.53 7/10/85 1:30 PM Oxygen Atmosphere 2.7 b.y. 0.4130 4029.70 1/28/93 5:30 AM

2. Data in graphical form – Take the results above and create a chart similar to Figure 1.13 in Grotzinger et al. 2006. Divide your graph into 5 Eons (preK, Elementary, Middle, High, and postHigh).

I strongly recommend that you work through the Melanie example before beginning your own calculations. I have also included the answer to a second calculation on the Melanie time scale.