Using the rock record to age date rock layers Geologic Time Using the rock record to age date rock layers

Let’s Start Thinking About This… You go to your refrigerator and look at the leftovers you wrapped in clear plastic wrap over the past 4 weeks but forgot to date. How would you determine which is freshest and which is oldest?

Relative Age Dating Geoscientists have devised a set of laws to help us understand the processes that shape our Earth I call them the “It’s So Obvious” Laws

Relative Age Dating Uniformitarianism- Earth’s processes are slow & gradual and have remained the same over time (rock cycle, water cycle, climate, etc.) If you know how a rock formed 1 thousand years ago… then you know how the same type of rock formed 3 billion years ago

Uniformitarianism The principle that the Earth has been shaped by GRADUAL changes throughout history and is shaped by GRADUAL changes that are still occurring.

Catastrophism Sudden, violent changes that shape the geologic structure of Earth.

Relative Age Dating Relative age dating is the science of determining the relative order of past events, without necessarily determining their absolute age.

Relative Age Dating Law of Stratification rocks form in layers or strata By looking at the surrounding layers, geoscientists can infer the relative age of a rock layer. Students will identify the relative age (not absolute age) of the person in each picture. They will only order them generally by age not determine how old each person is. Ask out of the 4, which were harder to order and why? Relative dating is the science of determining the relative order of past events, without necessarily determining their absolute age.

Relative Age Dating Law of Superposition Oldest rocks on the bottom Youngest rocks on the top

Relative Age Dating Law of Original Horizontality Layers originally deposited horizontally If they are folded or tilted… Then they have been disturbed or disrupted Remember the Geologic Column? NO SINGLE LOCATION ON EARTH HAS A CONTINUOUS SEQUENCE OF ALL THE ROCKS FORMED IN HISTORY

Relative Age Dating Law of Cross-cutting Relationships Rock faults or intrusions that cut through rock layers must be younger than the layers Fault – A break in the Earth’s crust along which blocks of the crust slide relative to one another. Have students add Fault to their vocabulary page.

Relative Age Dating Principle of Fossil Succession fossils succeed each other in a definite order Index Fossils Index fossils (also known as guide fossils, indicator fossils or zone fossils) are fossils used to define and identify geologic periods (or faunal stages). They work on the premise that, although different sediments may look different depending on the conditions under which they were laid down, they may include the remains of the same species of fossil. If the species concerned were short-lived (in geological terms, lasting a few hundred thousand years), then it is certain that the sediments in question were deposited within that narrow time period. The shorter the lifespan of a species, the more precisely different sediments can be correlated, and so rapidly evolving types of fossils are particularly valuable. The best index fossils are common, easy-to-identify at species level, and have a broad distribution—otherwise the likelihood of finding and recognizing one in the two sediments is minor. Just like the further into space we look, the further back in time we see. Can you remember how this statement can apply to astronomy?

Using Index Fossils Index Fossil Demo

How do Fossils Form? http://www.discoveringfossils.co.uk/Whatisafossil.htm https://www.youtube.com/watch?v=c_DCP4cLVNg (play up to 5min mark) Perisphinctes is an extinct genus of ammonite cephalopod. They lived during the Jurassic Period and serve as an index fossil for that time period. Pholidophorus is an extinct genus of teleost fish from the Triassic and Jurassic periods of Africa, Europe, and South America. Theropods first appeared during the Carnian age of the late Triassic period about 230 million years ago (Ma) and included the sole large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous, about 66 Ma. In the Jurassic, birds evolved from small specialized coelurosaurian theropods, and are today represented by 10,000 living species. Venericor bivalve - It is from the Tertiary period (65 - 1.8 million years ago) Elomeryx is an extinct genus of artiodactyl ungulate, and is among the earliest known anthracotheres. The genus was extremely widespread, first being found in Asia in the middle Eocene, in Europe during the latest Eocene, and having spread to North America by the early Oligocene. Cenezoic Era. Conulus is an extinct genus of echinoid that lived in the Cretaceous. Its remains have been found in Asia, Europe, and North America. Temnocidaris is an extinct genus of echinoid that lived from the Late Cretaceous to the Paleocene

Nonlinguistic Representation You are in charge of developing a non-linguistic graphic representation or illustration to allow the world to know more about the laws that shape out Earth aka the “It’s so obvious” laws. Below are the requirements: The artwork must demonstrate the concept in a real-life situation (at least 3 laws or principles) The centerpiece of the artwork must be a slogan or phase 4 colors must be used

Slogan "Superposition Pizzeria: We'll deliver in 30 minutes or less without any folds or tilts!"