Geology For Dummies. Alecia M. Spooner
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Название: Geology For Dummies

Автор: Alecia M. Spooner

Издательство: John Wiley & Sons Limited

Жанр: География

Серия:

isbn: 9781119652915

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СКАЧАТЬ field and observe events that have already happened, such as the formation of rocks, rock layers, or features of the landscape. Scientists make these observations without changing any aspect of the event or its result.

      Geologists also use another kind of experiment called a manipulative experiment. A manipulative experiment is done in a laboratory, where the scientist can manipulate or change certain factors in order to test which factors are most important in creating the observed outcome. In this case, multiple experiments can be done, each one testing the importance of a different factor (or variable), with the goal of zeroing in on the one (or ones) that explain the observed outcome.

      

Most importantly, a scientific experiment, whether it is a natural or manipulated experiment, must be repeatable. This means that the scientists must clearly describe the steps they have taken so that another scientist can repeat the same experiment and see if she too, gets the same result.

      Crunching the numbers

      After running experiments and making observations, a scientist is left with a large collection of information, or data, to use to draw a conclusion. Trying to find patterns in page after page of descriptive observations or lists of numbers is almost impossible. To find patterns in the data, a scientist uses statistics.

      

Statistics are a mathematical tool for describing and comparing information (observations) quantitatively, which simply means using numbers. By using numbers to describe the data, such as the number of times a certain characteristic is observed in different rock samples, scientists can organize and compare the patterns in the data using simple arithmetic.

      Some people find statistics intimidating because they seem like complicated mathematical formulas. But really, statistical methods are simple mathematics combined in a step-by-step sequence to uncover patterns in the data. Some statistics determine if two sets of data have overall similarities or differences. Others determine which variables are most important in creating the observed outcomes.

       Pie graph: This type of graph is best used for illustrating different pieces of a whole. The total of a pie chart must always add up to 100 percent.

       Bar graph: Also called histograms, bar charts are used to display information that can be sorted into different categories.

       Scatterplot: Scatterplot graphs illustrate how two types of data are related. Sometimes a scientist will use a scatterplot to look for patterns of relationship between the data types — by finding clusters of data points.

       Line graph: This type of graph is most commonly used to plot changes in a type of data over time, distance, or other variable.

 Schematic illustration of a) Pie chart, b) Bar chart, c) Line graph, and d) Scatter plot.

      Interpreting results

      After data has been described, compared, and graphed, the next step is interpreting the data to draw new conclusions and perhaps propose a new hypothesis for further testing. Often scientists will find that the patterns in their data bring up new questions for exploration.

      

If an experiment is designed well, the outcome (and collected data) should clearly prove or disprove the initial hypothesis. It is much easier and more common for a scientist to prove a hypothesis wrong than to prove it right. Finding that the hypothesis is incorrect helps rule out wrong ideas and is a very important step toward eventually finding an answer to larger questions that are being asked — and toward determining which hypothesis to test next.

      The challenge at this stage is applying previous knowledge (perhaps from previous experiments) to understand what the patterns in the data — or the relationships between variables — mean. Rather than finding answers to all the questions, scientists often find themselves asking new questions and circling back to the hypothesis stage, preparing to test another hypothesis.

      Sharing the findings

      When a scientist has completed experiments, analyzed data, and interpreted the results, he must share his findings and ideas with other scientists. Commonly this step is done through scientific journals that are peer-reviewed, meaning that other qualified and respected scientists have examined the experimental design and procedure, perhaps tested it themselves, and determined that the results and interpretation are reasonable.

      The peer-review step is very important. The process of having other knowledgeable scientists — other specialists in a particular topic — double-check the work helps find any errors. Errors may lead to false results or incorrect interpretations. Having more than one eye look for errors reduces the potential for moving forward on such false assumptions.

      The goal of scientific study is to better understand the world. Step by step, information is collected until a broader or deeper understanding is gained. Eventually, this understanding may be expressed as a scientific theory. As scientists create and share theories, they expand what we know about the world around us.

      It’s never “just a theory”

      Most people use the word theory to refer to an educated guess — a hypothesis. But scientifically speaking, a theory explains how some complex process works in the natural world. For example, the theory of plate tectonics that I cover in detail in Chapter 10 explains how crustal plates on the earth move around, forming mountains and volcanoes and causing earthquakes. The theory explains how all those geologic processes and resulting features are related to one another through the movement of crustal plates.

      

A theory does not, however, explain why something occurs. The theory of plate tectonics does not answer the question of why the surface of the earth is broken into plates that move around. It only describes how those plates move around and interact with one another to result in the features we observe.

      When a scientist describes something as a theory, she has come to the end of a long series of experiments and hypothesis testing. She is able to explain something so well, to provide evidence for that explanation (and to have that something accepted by other scientists as true) that it can be called a theory.

      

In other words, a theory is a hypothesis СКАЧАТЬ