Lesson 2: Geologic Time Scale

Front

What amazing journey does the geologic time scale define?

Back

All of the above

Answer explanation

The geologic time scale outlines the sequence of events in Earth's history, the age of rocks and fossils, and the history of life on Earth, making 'All of the above' the correct choice.

Front

What is an 'Era' in the context of geologic time?

Back

a long and distinct period of history with a particular feature or characteristic.

Answer explanation

An 'Era' is defined as a long and distinct period of geologic history characterized by specific features, making the first choice the correct answer. The other options describe shorter time frames or different concepts.

Front

What does 'Period' mean in geology?

Back

A division of time in the geological time scale.

Answer explanation

In geology, a 'Period' refers to a specific division of time in the geological time scale, marking significant events in Earth's history. This distinguishes it from rock formations, dating methods, or tools.

Front

Method used by geologists to describe the ages of ancient rocks.

Back

Radiometric dating

Answer explanation

Geologists often use radiometric dating to determine the ages of ancient rocks by measuring the decay of radioactive isotopes. This method is more precise for older rocks compared to carbon dating, which is limited to recent organic materials.

Front

Method used by geologists to determine the relative age of rocks.

Back

Stratigraphy

Answer explanation

Stratigraphy is the method used by geologists to determine the relative age of rocks by studying their layers and the sequence of deposition. This makes it the correct choice for understanding rock ages.

Front

How do geologists determine the absolute ages of rocks?

Back

By using radiometric dating.

Answer explanation

Geologists determine the absolute ages of rocks using radiometric dating, which measures the decay of radioactive isotopes. This method is akin to how Daniel uses clues to solve mysteries, providing precise age estimates.

Front

What is the Geologic Time Scale? It's a record of the geologic events and the evolution of life forms as shown in the _______ and fossil records.

Back

Geologic Time Scale

Answer explanation

The Geologic Time Scale is a system that organizes Earth's history based on geological events and the evolution of life, as shown in the Geologic Time Scale and fossil records. Thus, the correct answer is 'Geologic Time Scale'.

Front

What percentage of Earth's history does the Precambrian Time cover?

Back

88%

Answer explanation

The Precambrian Time covers about 88% of Earth's history, making it the longest geological time period. This includes the formation of the Earth and the development of early life forms.

Front

When did the Precambrian Time, which started 4.6 billion years ago, end?

Back

541 million years ago

Answer explanation

The Precambrian Time ended 541 million years ago, marking the beginning of the Cambrian period. This is a significant point in Earth's history when complex life forms began to emerge.

Front

What are the three grand units of time called that divide the era from the Precambrian to the present?

Back

Eons

Answer explanation

The correct answer is 'Eons', which are the largest divisions of geological time. They encompass significant periods in Earth's history, including the Precambrian and the present, while 'Epochs', 'Periods', and 'Ages' are smaller subdivisions.