Good Afternoon and Happy Tuesday Today: Did you know that we live closer to the time of Tyrannosaurus rex than T. rex lived to the time of Stegosaurus (Smithsonian.com) 66 – 68 million years ago 150 – 155 million years ago 66 – 68 million years 82 – 89 million years

Have you turned in these assignments? More Things To Make Your Head Hurt video study guide(yellow or white) Interpreting Rock Strata Level 2 (blue) Half Life Problems (blue)

Geological Time - really, really, really long! Motion pictures are generally projected at 32 frames per second. Therefore, each frame (image) is on the screen for only split second- let each frame represent 100 years. Start movie at present and go back in time. The Declaration of Independence would show up 1/16 of a second into the movie. The Christian era (BC-AD boundary) would be 3/4 of a second into the movie. The most recent Ice Age would be 7 seconds into it. The movie would run about 6 hours before we got to the end of the Mesozoic era (extinction of the dinosaurs). We'd have to watch the movie for about 2 days to see the beginning of the Paleozoic era (macroscopic life). The whole movie (to the beginning of geologic time on Earth) would be approximately 16 days long! Motion pictures are generally projected at 32 frames per second. Therefore, each frame (image) is on the screen for only split second- let each frame represent 100 years. Start movie at present and go back in time. The Declaration of Independence would show up 1/16 of a second into the movie. The Christian era (BC-AD boundary) would be 3/4 of a second into the movie. The most recent Ice Age would be 7 seconds into it. The movie would run about 6 hours before we got to the end of the Mesozoic era (extinction of the dinosaurs). We'd have to watch the movie for about 2 days to see the beginning of the Paleozoic era (macroscopic life). The whole movie (to the beginning of geologic time on Earth) would be approximately 16 days long!

The Fundamental Rule of Absolute Ages The Earth is older than everything on or in it -Except its atoms -All ages are minimum ages

Radiometric Dating: Half-Life

Present Radiometric Dating Methods More Recent Samples C Yr. Primordial (ancient) Samples K-Ar (K-40) 1.25 B.Y. Rb-Sr (Rb-87) 48.8 by U M.Y.

The Geologic Time Scale

Some Geologic Rates Cutting of Grand Canyon 2 km/3 m.y. = 1 cm/15 yr Uplift of Alps 5 km/10 m.y. = 1 cm/20 yr. Opening of Atlantic 5000 km/180 m.y. = 2.8 cm/yr. Uplift of White Mtns. (N.H.) Granites 8 km/150 m.y. = 1 cm/190 yr.

Some Geologic Rates Movement of San Andreas Fault 5 cm/yr = 7 m/140 yr. Growth of Mt. St. Helens 3 km/30,000 yr = 10 cm/yr. Deposition of Niagara Dolomite 100 m/ 1 m.y.? = 1 cm/100 yr.

1 Second = 1 Year 35 minutes to 1 A.D. 1 hour+ to pyramids 3 hours to retreat of glaciers from Wisconsin 12 days = 1 million years 2 years to extinction of dinosaurs 14 years to age of Niagara Escarpment 31 years = 1 billion years

The Fossil Record We know that as you look at deeper layers of sedimentary rock we are looking back in time (deeper layers = older rock) The ages of these layers can be determined by radiometric dating When we compare the ages of the rock with the fossils found in them, another pattern emerges Types of living things on earth are not constant – organisms have changed. There are many fossils of organisms that no longer live on Earth. Fossils of simpler organisms are found in older rock layers

Flora and Fauna of Different Time Periods Pre-Cambrian Simple, single-celled forms of life appear 3.8 billion years ago Algae Bacteria Cyanobacteria (blue-green algae) begins producing free oxygen (photosynthesis)

Flora and Fauna of Different Time Periods Paleozoic Cambrian Explosion of life Marine invertebrates (trilobites and brachiopods)

Flora and Fauna of Different Time Periods Ordovician The 1st animals with bones appear Dominant animals are still trilobites, brachiopods and corals Cephalopods – squid and octopus like creatures Silurian First land plants - mosses Coral reefs expand and land plants begin to colonize barren land. First millipede fossils and sea scorpions (Euryptides) found in this period Devonian Dominant animal: fish Oceans and still freshwater fish migrate from southern hemisphere to North America. Amphibians, evergreens and ferns appear

Flora and Fauna of Different Time Periods Carboniferous First seed plants appear Lizards and winged insects first appear. Permian Reptiles spread across continents. 90% of Earth’s species become extinct due to volcanism in Siberia. This marks the end of trilobites, ammonoids, blastoids, and most fish. Mesozoic Triassic First dinosaurs appear First mammals- small rodents appear First turtle fossil from this period

Flora and Fauna of Different Time Periods Jurassic Dinosaurs flourish “Golden age of dinosaurs” First birds appear Cretaceous T-Rex develops First snakes and primates appear Deciduous trees and grasses common First flowering plants Mass extinction marks the end of the Mesozoic Era, with the demise of dinosaurs and 25% of all marine life.

Were The Dinosaurs Failures? Dinosaurs: 150,000,000 years Recorded History: 5000 years For every year of recorded history, the dinosaurs had 30,000 years For every day of recorded history, the dinosaurs had 82 years For every minute of recorded history, the dinosaurs had three weeks

Flora and Fauna of Different Time Periods Cenozoic Tertiary First horses appear and tropical plants dominate (Paleocene) Grasses spread and whales, rhinos, elephants and other large mammals develop. Sea level rises and limestone deposits form in S.C. (Eocene) Dogs, cats, and apes appear (Oligocene) Horses, mastodons, camels, and tigers roam free in S.C. (Miocene) Hominids develop and the Grand Canyon forms (Pliocene) Quaternary Modern humans develop and ice sheets are predominant- Ice age (Pleistocene) Holocene Humans flourish (Holocene)