Reviewing a middle-school book in earth science

Glencoe Earth Science
1999. 792 pages. ISBN of the student's edition: 0-02-827852-6.
Glencoe/McGraw-Hill, 936 Eastwind Drive, Westerville, Ohio 43081.
(Glencoe/McGraw-Hill is a division of the McGraw-Hill Companies.)

An Old, Weak Book with New Window Dressing

Peter U. Rodda

I found some favorable things to say about the 1993 book, but I also observed that it had many shortcomings, and I told how it could be improved. Its major defect was its incoherence: The 1993 Merrill Earth Science was really two separate, poorly integrated books that had been bound in the same set of covers. One book dealt with science, the other focused on environmental problems and evidently tried to promote environmental activism.

In my review of the 1995 version I said that it was virtually identical with the 1993, both in content and in appearance. The only significant changes involved the "Activity" pages. Many of them had been rewritten or redesigned or retitled, and some had been replaced.

Now we have the 1999 version. Apart from the new title, in which Glencoe has been substituted for Merrill, is this 1999 book any different from the previous versions?

Yes, it is. It is bigger, heavier and more cluttered. It has more pages, bigger pages, bigger illustrations, and a heavier load of sidebars, headlines and subheadings that make the text harder to follow -- in other words, it has a lot of new window dressing. Many of the illustrations are new, but others are not. In various cases, Glencoe's designers have reprinted an old picture in a new position or at a different size, or they have made an old picture look different by reversing it. Among the illustrations that really are new, some are better than the corresponding illustrations in the 1993 and 1995 books, but others are not. Sometimes the designers have simply substituted a new picture for an old picture of the same subject. (Chapter 4 used to have a picture in which the chalk cliffs of Dover faced to the right. Now it has a new picture in which the cliffs face to the left! That is silly, and the adjacent text -- which hasn't been changed at all -- is sillier. Glencoe is still telling students that "When your teachers use naturally occurring chalk to write with, they're actually crushing and smearing the calcite shells of once-living ocean animals." In truth, natural chalk disappeared from American commerce, and from American classrooms, long ago. The "chalk" that teachers use today is made from synthetic calcium sulfate.)

The 1999 book would be better if the designers and illustrators had paid less attention to novelty and more attention to getting things right. As it is, the book contains a number of pictures that are seriously flawed. For example:

• Figure 4-11, dealing with compaction and cementation, is hopeless. In the sequence of sketches that supposedly illustrate compaction, nothing seems to be compacted -- but in the sketches that supposedly show cementation, I see grains that evidently have been deformed by compaction!

• Figure 5-14, purporting to show that "Contour lines form Vs whenever they cross streams," is fanciful. The topography shown in the illustration doesn't correspond to the topography indicated by the contour lines.

• In the section called "Pangaea" (on pages 294 and 295) there is a picture showing the continents as they exist today. There is no picture of Pangaea.

• Figure 9-6, dealing with earthquake waves, is baffling. If it is supposed to show a fault that has produced a very small fault scarp, then it is poorly drawn and unclear. If it is supposed to show an open fracture along the trace of a fault that has undergone no horizontal or vertical movement, then it is just wrong.

On the other hand, I have noticed some good work in the section titled "Middle and Recent Earth History." In the earlier books, this section included a painting in which an adult Protoceratops watched while some of its eggs hatched. The painting was based on a museum exhibit that, we now know, was erroneous. The eggs in the exhibit were Velociraptor eggs, not Protoceratops eggs. Glencoe's illustrators have discarded the old picture and have replaced it with a painting that shows an adult Maiasaura looking at its newly hatched young. This is a commendable improvement.

Glencoe's writers still don't grasp what science is or how scientists work, they continue to confuse science with technology, and their section "Using Scientific Methods" (page 16) is misconceived and misnamed. It doesn't deal with science. It is a fanciful story about choosing an appropriate technology for retarding soil erosion.

The nature and the processes of science become even more obscure when the writers produce a passage that ostensibly deals with the origin of the Grand Canyon. It says, in part:

[Q]uiet seas covered much of the canyon area. When the seas retreated, the minerals and other bits of debris in the water formed layers of sandstones, limestones, and shales. Forces within Earth tilted and folded these layers. Then, over hundreds of millions of years, more layers of shales, limestones, and sandstones formed over this area. The youngest rocks in the canyon are about 225 million years old.

Geologists have proposed many ideas as to how the Grand Canyon formed. Some thought a single, catastrophic event formed the gorge, while others hypothesized that it was a remnant of a once-molten planet. The most accepted hypothesis, however, is that the Colorado River slowly carved the canyon during the past 15 to 20 million years. [page 26]

The writers thus show a complete lack of understanding of the geology they are trying to describe, and their use of the term hypothesis is simplistic and grotesque. That the Grand Canyon is a product of erosional processes -- processes that are still at work in the Canyon now -- isn't a hypothesis but a fact. In the lexicon of science, fact means an inference which is so strongly supported by evidence that only an irrational person would refuse to accept it, provisionally, as a valid description of some aspect of nature. Though the details of the Grand Canyon's history are complex and controversial, no rational "geologists" imagine that the Canyon is "a remnant of a once- molten planet" or that it arose from a "single, catastrophic event." However, the notion that the Canyon resulted from one great catastrophe is popular among some creationists, who claim that the Canyon was formed by supernaturally fast erosion when the waters of the biblical Flood subsided and flowed away to nobody-knows-where.

As before, the writers admonish students to use critical thinking, though the writers themselves often avoid it. For example, their efforts to present the concepts of mass and weight (in chapter 1) are confused and self-contradictory. They say that "Mass is a measure of the amount of matter in an object" and "The standard unit of measure for mass is a kilogram," while "Weight is a measure of gravitational force on a mass" and "The standard unit for weight is a newton." On the same page, a photo shows a boy standing on a drugstore scale, and the caption says: "When you weigh yourself, you are measuring the force of gravity" -- but the dial on the scale is clearly labeled "KILOGRAMS." Doesn't this mean that the scale is reporting mass rather than weight? If the scale tells weight, why isn't the scale's dial marked "NEWTONS"? And what is this "newton" stuff anyway? No one goes to a store to buy a newton of sausages or five newtons of apples. Glencoe's writers make no effort to relate newtons to the units of weight with which the student is familiar.

These writers scorn critical thinking again when they try to introduce the idea that a substance has physical properties (page 44). "The properties that you can observe without changing a substance into a new substance are physical properties," they say. Then they ask the student to ponder the "physical properties" of a pair of blue jeans: "If you say your jeans are blue, soft, and about 80 cm long like the ones in Figure 2-10, you've described some of their physical properties."

But a pair of jeans isn't a substance. A pair of jeans is a structure composed of several discrete substances, so the concept of physical properties -- as the writers themselves have defined it -- doesn't apply. Furthermore, a length of "about 80 cm" can't be a physical property of any substance, because a substance is not finite and does not have any particular dimensions. How long is quartz? How wide is calcite? How tall is carbon tetrachloride? Such questions are clearly nonsensical. Glencoe's writers don't grasp the difference between a substance and a specific structure or a specific object, and their passage about physical properties is worthless.

Confusion, obscurity and fuzzy thinking recur in later parts of the book, too. In the chapters on minerals and rocks, for example, I see the same logical inconsistencies and other mistakes that I noticed in the 1993 and 1995 books. As before, the writers' odd, narrow definition of mineral precludes their presenting any legitimate discussion of mineral resources. To make matters worse, the unit titled "Earth's Resources" -- which appeared in the earlier books and which included some discussion of fossil fuels -- has been discarded. In the 1999 version, fossil fuels are mentioned only in a brief section about global warming.

On pages 55 and 56 the writers tell of a proposal to store nuclear wastes at Yucca Mountain, Nevada, and then they pose questions to the student: "Should the Department of Energy abandon the study of the Yucca Mountain nuclear storage site? If yes, what other arrangements might be made in order to cope with the nuclear waste? If no, how would you alleviate the concerns voiced about the dangers of volcanoes, earthquakes, and groundwater contamination at the Yucca Mountain site?" But the student hasn't yet learned anything about volcanoes, earthquakes, groundwater or any of the other geological matters that are relevant here, and it is foolish to ask such questions so early in the book.

In Unit 2, titled "The Changing Surface of Earth," the 7-page section about maps fails to mention geological maps. Unit 2 ends with a project in which students must fashion a board-game dealing with some challenges and hazards of a journey over the old Oregon Trail. This exercise could conceivably teach something about the westward expansion of the United States, but it has almost nothing to do with the topics (e.g., weathering, erosion, glaciers) that are covered in the body of the unit.

Unit 3 -- "Earth's Internal Processes" -- has been reorganized for the better, and the treatment of volcanoes is more coherent, but the passages about batholiths and intrusive rocks are still out of place. They simply don't belong here.

In Unit 4, "Change and Earth's History," the section on radiometric dating is still obscure, and it still contains the claim that "Before radiometric dating was available, many people had estimated the age of Earth to be only a few thousand years old [sic]." As I explained in my review of the 1995 book, that claim is misleading and unacceptable. The people who believed that Earth was "only a few thousand years old" had derived that belief from religious lore -- they had not "estimated" the age of Earth in any scientific way.

Later in Unit 4, the history of life on Earth is badly distorted. Invertebrates are mentioned only in the section called "Early Earth History," and the student must infer that the invertebrates disappeared after the Paleozoic Era and were entirely replaced by vertebrates. The truth is that invertebrates occur in profusion throughout the fossil record, and most of the animals that inhabit Earth today are invertebrates.

Although Glencoe Earth Science shows us some marginal improvements, it still has too many failings. The major failing is that it still is an inept jumbling of a science book and a book about environmental matters -- especially the technological aspects of such matters. Nearly all of the environmental material in Glencoe Earth Science is concerned with technology, which the writers define as "the use of scientific discoveries." The emphasis on technology in Glencoe Earth Science promotes the common misconception that science is chiefly the search for dramatically new ways to do tasks, build things, run things and use things, and it can only distract students from learning any real earth science.

Peter U. Rodda, a geologist and paleontologist who specializes in fossil mollusks from the Cretaceous Period and more recent times, is a research professor in the Department of Geological Sciences at the University of Oregon in Eugene. He also is an emeritus curator of geology at the California Academy of Sciences in San Francisco.

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