EarthViewer (for iPad) is an informative and fun way to learn about our “deep history.” This app, geared to science teachers and students, covers 4.5 billion years of geological and atmospheric information. Cool animations let you watch the continents drift on a virtual globe. The app shows changes to the planet’s temperature, oxygen and carbon dioxide levels, the length of the day, and the Sun’s luminosity, from the earliest eons through modern times. Even better, the app is free.
EarthViewer belongs to the Howard Hughes Medical Institute’s BioInteractive series of free resources geared to science teachers and students. The app is well researched and packed with referenced information. The app worked smoothly, without any glitches. It’s for use with the iPad only; I tested it on an iPad 2.
When you open the app, a screen shows you how to move between three main timeline views: the default Phanerozoic view, which covers the past 540 million years; Deep History, which goes back 4.6 billion years; and Modern (the past 100 years). You are given the option of viewing a tutorial, with short movie clips showing the app’s operation, or entering the app itself.
A Global Time Machine
A 3D globe, which can be rotated in any direction, takes up most of the right-hand part of the screen. To its left is a vertical slider; you can think of it as a “time machine” to take you back to earlier ages; by default the slider spans 540 million years. To the slider’s left are strips showing the Eon (Phanerozoic, in this view); Era (Paleozoic, Mesozoic, or Cenozoic); and Period (11 periods, ranging from the Cambrian to the Neocene. (The current Quaternary Period, which spans the most recent 2.6 million years, is barely visible and too small an interval to be identified by name.)
Clicking on a label, whether for eon, era, or period, brings up a brief popup description. For example, the Phanerozoic Eon’s name is derived from ancient Greek and means “visible life”, and represents the time during which the majority of macroscopic organisms—whether seaweeds, mushrooms, plants, or animals—have lived.
By moving the slider, you can watch the continents drift; for example, 110 million years ago (abbreviated to MYA in the app), West Africa was connected to Brazil, and 210 MYA, Africa, North America, and South America fit neatly together like pieces in a jigsaw puzzle. Beneath the slider, forward arrow, backward arrow, and pause buttons let you animate this motion forward or backwards in time to watch 540 million years of continents separating, colliding, merging, re-forming, and pulling apart. Meanwhile, the locations of modern cities slowly drift with their continents, migrating in latitude and longitude.
By vertically pinching the Eon/Era/Period list on the left side of the screen, you can backtrack 4.5 billion years in time to the “Hadean Eon” before the accretion of the oldest known rocks. The farther back in time you go, the less certain our geological knowledge goes, as much of the early geological record has been obliterated by our planet’s evolution.
Continue Reading: Global and Local Climate Change
Global and Local Climate Change
If you stretch the timeline all the way out, you’ll see just the modern era, the past 100 years. There, the globe shows variations from the average mean temperature from 1951-1980, color coded from dark blue (2 degrees Celsius lower) to red (2 degrees higher). As you might guess, for most of the globe the mean temperature is higher; this is most pronounced in the Arctic, Europe, the Middle East, and North Africa. A few areas, like much of the western Pacific, are slightly cooler than average. Antarctica runs hot and cold, with the mean temperature for some areas much higher than average, though in one zone it’s much lower.
Text to the upper left of the globe tells you what era you’re viewing, or time in MYA, and the percentage of oxygen and carbon dioxide in the atmosphere. To the left of the globe, you can see the day length, as well as a compass that lets you align the globe. A billion years ago, a day was only about 20.5 hours long, while 4.5 billion years ago, it was 17.5.
Along the bottom of the app, to the right of the arrow keys, are additional buttons: Charts; View; In Depth; Teachers; and Info. Charts lets you view long-term changes in our planet’s temperature, oxygen and carbon dioxide content, day length, and the Sun’s luminosity. Some of these factors—such as the Sun’s luminosity over time—are of necessity inferred through various models, although temperature and carbon dioxide and oxygen levels are measured directly for much of the modern era. In the modern era, an additional factor, biodiversity (percentage change in the abundance of 2,700 animal species since 1970) can also be graphed.
View lets you add additional data to the globe; by default, Grid (latitude and longitude) and Cities are on. You can add Fossils, showing discovery sites like Lucy and Ardi and Oldupai Gorge in East Africa, the La Brea tar pits in California, and the Burgess Shale in Canada, for example as shovel icons. Clicking on one describes the find and its importance.
Fossils, Meteor Impacts, and Mass Extinctions
Impact Events shows where large meteors or small asteroids have hit Earth; among those shown are Chicxulub (which caused the extinction of the dinosaurs), Sudbury in Ontario, and Chesapeake, which carved out Chesapeake Bay. The crater’s age, diameter, and geographical coordinates are shown if you click on the impact site.
Mass Extinctions adds the dates of 4 mass extinctions to the timeline: Cretaceous, Permian (the largest on record); Devonian; and Ordovician, and describes them. Biological Events adds events such as the emergence of the first land plants, and the Genus Homo, our hominid ancestors, while Geological Events shows the formation of supercontinents such as Pangaea, Rodinia, and Nuna, snowball glaciations (two glaciations events around 700 MYA covered the Earth in ice), the earliest rocks, and more.
The In Depth button explores topics such as the greenhouse effect, plate tectonics, mass extinctions, the oxygenation of the planet, and the origins of life. The Teachers button provides a quick guide for using the app in the classroom, references for the primary research on which the app is based, and info about the HHMI and its BioInteractive series.
EarthViewer is a wonderful app for exploring our planet’s geological and climate history, and get a better idea of the changes that Earth has been through, from billions of years ago up to the present. It is worth downloading for the animations of the drifting continents alone, but goes far beyond that by providing a wealth of information about our planet’s history. This includes the marking of atmospheric, geological, and biological events and includes a look at how carbon dioxide levels and mean temperatures have been increasing in recent years, while biodiversity has been reduced.
If EarthViewer has a shortcoming, it’s that it could provide more detail on various subjects. There are other important fossil sites and impact sites that could be added. But the app does a great job in providing an overview of a lot of related subjects, it’s easy to learn and use, and has a tutorial to help, if need be. Whether you’re a teacher, a student, or have a personal interest in geology, paleontology, biology, and/or climate change, there’s no reason not to download this free Earth science app. It’s an easy pick as an Editors’ Choice as an educational iPad app.
Copyright © 2012 Ziff Davis, Inc