Page 29 - Laboratory Manual in Physical Geology

ACTIVITY ACTIVITY

1.3 Modeling Earth Materials 1.4 Measuring and Determining
and Processes Relationships
|
THINK How and why do geologists make THINK How and why do geologists measure
About It models of Earth? About It Earth materials and graph relationships
| among Earth materials and processes
OBJECTIVE Make models and use them to of change?

understand Earth processes and the relative
proportions of Earth’s physical spheres. OBJECTIVE Measure Earth materials using basic

Geologists make models of things that are too scientific equipment and techniques, and determine
large or small to visualize and study. A scale model relationships using rates and graphs.
is a physical representation of something that is PROCEDURES
actually much larger or smaller and has the same 1. Before you begin , read the following background
proportions as the actual object. For example, a toy information on measuring Earth materials,
car is a small model of an actual car. The ratio scale of determining rates, and graphing relationships.
the model is the ratio by which the actual object was This is what you will need :
enlarged or reduced to make the scale model. If a toy
car is 20 centimeters long and the actual car was 800 ___ Activity 1.4 Worksheets (pp. 32 – 34 ) and pencil
centimeters long, then the ratio scale of model to with eraser
actual car is 20:800, which reduces to 1:40. A 1:40 scale ___ calculator, ruler
model has a fractional scale of 1/40, meaning that the ___ other materials provided in the lab: 10 mL and
actual car is 40 times (40x) larger than the model. 500 mL or 1000 mL graduated cylinders, small

Geologists also make models to study how things piece of grease-based modeling clay, gram
work. They design laboratory experiments in which balance or scale, and basin of water
they can control variables and test ideas before they 2. Then follow your instructor’s directions for
implement them in real life. For example, it is much completing the worksheets.
cheaper and safer to build and test many models of
earthquake-proof designs before constructing an
actual earthquake-proof building. operate like this: liquid water (hydrosphere) evaporating
from Earth’s surface produces water vapor (atmospheric gas).
PROCEDURES
The water vapor eventually condenses in the atmosphere to
1. Before you begin , this is what you will need :
form aerosol water droplets (clouds). The droplets combine
___ blue pencil or pen to form raindrops or snowflakes (atmospheric precipitation).
___ calculator, ruler, drafting compass Snowflakes can accumulate to form ice (cryosphere) that
___ several coins sublimates back into the atmosphere or melts back into
water. Both rainwater and meltwater soak into the ground
___ Activity 1.3 Worksheets (pp. 30 – 31 ) and pencil
(to form groundwater), evaporate back into the atmosphere,
with eraser
drain back into the ocean, or are consumed by plants and
2. Then follow your instructor’s directions for animals (which release the water back to the atmosphere via
completing the worksheets. the process of transpiration).
In addition to water that is moving about the Earth
system, there is also water that is stored and not circulating
without flames). And while some chemical reactions are at any given time. For example, a very small portion of
irreversible (decomposition reactions, like tooth decay), Earth’s water (about 2% of the water volume in oceans) is
many are reversible (under changing conditions, the currently stored in snow and glacial ice at the poles and on
chemicals react again and recombine back into the starting high mountaintops. Additional water (perhaps as much as
compounds). So these processes of change, powered 80% of the water now in oceans) is also stored in “ hydrous ”
by energy transfer and transformation, cause chemical (water-bearing) minerals inside Earth. When glaciers melt,
materials to be endlessly cycled and recycled. One of these or rocks melt, the water can return to active circulation.
cycles is the hydrologic cycle , or “water cycle.” The endless exchange of energy and recycling of water
The hydrologic cycle ( FIGURE 1.7 ) involves several undoubtedly has occurred since the first water bodies
processes and changes in relation to all three phases of water formed on Earth billions of years ago. Your next drink may
and all of Earth’s spheres (global subsystems). It is one of include water molecules that once were part of a hydrous
the most important cycles that geologists routinely consider (water-bearing) mineral inside Earth or that once were
in their work. The hydrologic cycle is generally thought to consumed by a thirsty dinosaur!

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