Geologic Time Scale Organizes Earth's History

Many students don't understand what the "geologic time scale" is. The time scale is a way to show the various time periods of Earth's history in chronological order. Basically it's an outline that facilitates communications between geologists and paleontologists, etc. by making it easier for them to determine relationships between rock formations and fossils, and describe the timing of past events. CLICK HERE to see an interactive version of the time scale, courtesy of the University of California Museum of Paleontology. Another, printable (pdf) version, is provided by the Geologic Society of America: CLICK HERE to open it.

The time scale was established in the 1800s, using principles of relative dating (fossils, super-position, cross-cutting relationships, etc.). In the 20th century radiometric dating allowed dates to be added. Earth's history was divided into major time periods called "eons", and then sub-divided into even smaller spans of time (eras, periods, epochs).

Students may wonder why one period ended and another began. Each period was different from than those before and after it; different organisms, different climate, etc. . . and one of the challenges of geology is figuring out what caused these changes. In some cases the ends of time periods coincided with mass extinction events. For example, most scientists believe the extinction event that abruptly ended the Mesozoic Era was caused by an asteroid impact. Unfortunately, not all transitions are so well-understood.

And the resource is . . .
To strengthen your understanding of Earth's history, read Why Geology Matters (2011) by Doug Macdougall. Macdougall explains significant events in Earth's history and provides a perspective that brings together oceanography, meteorology, astronomy, and geology. Macdougall also wrote "Frozen Earth: The Story of Once and Future Ice Ages"; another one of my favorites.

Moon Phase Interactive Tutorial

Check out this fun tutorial/review of moon phases provided by the ASPIRE Lab in conjunction with the University of Utah. The moon phase tutorial includes 3 interactive activities for students to check their understanding. CLICK HERE to access the tutorial. The interactive windows will open up when you select the boxes titled "Activity 1", etc. This is a great review tool for those students who are having a hard time understanding moon phases.

The ASPIRE Lab offers several other activities created by teachers for teachers, many of them related to Earth Science.

Hands-On Watershed Activity

In order to understand many important water-related issues, students need to understand the existence and dynamics of watersheds (a.k.a. drainage basins). This "Island Watershed Activity" will help them realize how an abandoned mine can cause the presence of dissolved metals in a stream many miles from the mine site, and how farming practices in the Midwest can contribute to a "dead zone" in the Gulf of Mexico. CLICK HERE to read about the details and print a student handout. The activity takes the better part of three class periods to complete (50-minute periods).

Cool Paleogeography Site

Dr. Ron Blakey of Northern Arizona University has provided an amazing collection of maps depicting the Earth at various times in the past. CLICK HERE to read about the terms of use, etc. and then select "Gallery of Products" or "Enter the Library" to gain access to the maps. The colorful maps can be used to enhance presentations related to plate tectonics or Earth's history. The map at the right shows the Earth 340 million years ago, during the Mississippian Period.

Reminder: Watch "NOVA: Deadliest Volcanoes" Wednesday, Jan. 4 on PBS.

NOVA Shows Students How Science Works

It looks like NOVA will be featuring some really interesting Earth Science topics over the next couple months. CLICK HERE to see the schedule. Scroll down and select "More Upcoming Posts" to see programing through February 1st. NOVA comes on Wednesday evenings on PBS (check your local listings). Although I watch NOVA for my own education and enjoyment, I do show some episodes to my students throughout the year. Typically I make up a worksheet with 10 questions for them to answer as they watch. The programs are especially effective at showing students how real scientists do research. Here are the titles of upcoming shows related to Earth Science.

December 28: Extreme Ice and Secrets Beneath the Ice (both re-runs)

January 4: Deadliest Volcanoes (new)

February 1: Ice Age Death Trap (new)

Here are some downloadable worksheets from some of the NOVA programs that I use in class.

Magnetic Storm

Mystery of the Megavolcano (Toba)

The Last Extinction

Animate these Global Maps from NASA's Earth Observatory

NASA satellites provide a global view of what’s happening on our planet. To explore how key parts of Earth’s climate system change from month to month, CLICK HERE. There are 16 different maps that you can animate to watch how different aspects of the Earth change over several years. One of my favorites is "snow cover".

A Little Culture for You

As I was looking for a way to make Chinook winds more interesting to my students, I found a great music video on YouTube called, "The Bear Who Stole the Chinook", by Jack Gladstone. Gladstone's song is based on a Native American story about the Chinook winds, which deliver heat to the east slopes of the Rockies in Montana and Alberta. A search led me to maps that revealed a remarkable correlation between the part of Montana-Alberta where Chinook winds are most common, and the homeland of the Blackfoot Confederacy.

CLICK HERE to find out how to use the video, learn more about these warm winds, and download a PowerPoint presentation (includes the maps and many more images).