Science test 9/23/22

When was the first evidence of a single celled fossil discovered?

3.7 bya

How long have modern humans been on Earth

300,000

When was the Earth formed?

4.6 billion years ago

How was the Earth formed ?

A cloud became smaller and denser. It began to spin and created the sun and the Planets.

How are models used to represent the history of Earth?.

A representation of an object or process that makes important aspects easier to observe

Why do new eras begin>

A sudden change in the types of fossils present, may mark the dividing line between different geologic time periods

What is scientific theory?

An idea/theory that is not scientifically proven or tested

What era do we live in?

Cenozoic Era

How is evidence used to determine major extinctions in the geologic timeline using rock strata?

Certain major events in Earth's history can also be useful for matching up the ages of rocks from different parts of the world, found in rock strata.

How to calculate half life?

Half-lives are the time it takes for 50% of the element to turn into another element.Example: 700 million yrs for 50% of Uranium-235 to turn to Lead

What is the scientific name for modern human species?

Homo Sapiens

What is the geological time scale?

It is a model used to study the history of Earth that divides the history into blocks of time such as eras and periods.

What is relative dating?

It is determining the age of a rock

What is rock strata?

It is the layer of a rock

What is absolute dating?

It is the process of determining the approximate age of a rock, fossil, or event.

What is the Law of Superposition?

It says that older layers of rock are found below younger layers of rock.

How is rock strata formed?

Over time, different kinds of sediments are deposited, and these form the distinct layers.

Geologic time scale from largest to smallest

Precambrian, Paleozoic, Mesozoic, Cenozoic

How is a fossil used as in index fossil?

They arewidely distributed organisms that lived during only one short period of time. They help define geological periods.

Why do scientists use the geological time scale?

They use it to order when events happened

How do you use fossils to compare rocks in different locations?

You can do this by looking at the layers and matching it up with the locations

What is scientific law?

a description of a natural phenomenon that has been repeatedly tested and appears to be without exception.

What is scientific evidence?

a well-tested explanation of scientific observations and experiments that is supported by a large amount of evidence. ex: Big Bang Theory