EAS 10600/ENGR 10610
Lecture 2 – Systems Science and
Intro. To Earth Materials
Definitions
System = that portion of the earth that we will
consider in a scientific study. Must be
contiguous and have clearly defined boundaries.
The entities in the system must have something
in common.
Open system –
Closed system –
Isolated system –
In any system, conservation of energy
and matter must apply.
Open system:
Inflow - Outflow = Change in Storage
Source = a location or process that adds
matter and/or energy to the system
Sink = a location or process that removes
matter and/or energy from the system
Box Models
Each place where a particular chemical entity is found
is represented by a box. The box is sometimes referred
to as a reservoir.
in-flowing
stream
Out-flowing
stream
POND
Evaporation
If input = output, we can define:
Residence time = Total Amount/Throughput.
Closed System:
0 = Change in storage, at least for matter
In a closed system, matter can move around
from place to place, but the total amount
cannot change. This leads to cycles. One
example is the water cycle, sometimes called
the hydrologic cycle.
The Hydrologic Cycle
Source: Hudson, Living with Earth, 2011
• A system is at equilibrium, when there are no
overall changes in the parameters that
describe the system.
• Note that equilibrium does not imply that
there are no flows of matter, just that the
inflow and outflows match, so that there is no
overall change. If a system is at equilibrium,
but the flows are not zero, then it is called
dynamic equilibrium.
Feedback – when the effect of a process changes the
input to the process or the process itself
Diagram of a Public Address System Without Feedback:
Diagram of a Public Address System With Feedback:
Example of Feedback in the Earth System:
Effect of CO2 on Temperature
Without Feedbacks:
With Two Feedbacks:
Earth Materials
Atmospheric Composition: Crustal Composition (by
weight):
78% Nitrogen (N2)
21% Oxygen (O2)
1% Other
45% Oxygen (O-2)
27% Silicon (Si+4)
8% Aluminum (Al+3)
6% Iron (Fe+2,+3)
5% Calcium (Ca+2)
3% Magnesium (Mg+2)
2% Sodium (Na+1)
4% Other
Structure of the Solid Earth
Solid Earth Materials - Definitions
Mineral – a naturally occurring, inorganic solid, that
possesses an orderly crystalline structure and
a definite chemical composition
Native element – a chemical element present in pure
form in the solid earth. (Examples include
gold and native copper.)
Rock – an aggregate of minerals
Crystalline Structure
Diamond
Graphite
Other Types of Bonding
Metallic bonding – bonding in which
electrons are shared by atoms
throughout the material
Van der Waals bonding – weak
bonding due to fluctuations in the
electron clouds in atoms
Rock – an aggregate of minerals
Types of Rocks
1. Igneous – formed by the cooling and
crystallization of melted rock material
2. Sedimentary – formed at or near the earth’s
surface from the products of weathering
3. Metamorphic – formed by the alteration of
pre-existing rocks by heat, pressure, or
chemically active fluids
Igneous Rocks
• Formed in association with volcanism
• Two basic types:
– Extrusive rocks are formed at the earth’s surface
by the cooling and solidification of erupted lava
– Intrusive rocks are formed beneath the earth’s
surface by the solidification of melted rock
material (called magma) that never made it to the
surface
Sedimentary Rocks
• Weathering is the sum of the natural
processes that take pre-existing rocks (of any
type) and breaks them up into loose solid
pieces or chemically alters them into new
loose mineral grains or material dissolved in
water.
• This loose material (called sediment) is then
moved around and accumulates into layers
that eventually solidify into solid rock.
Metamorphic Rocks
Some rock layers can be heated up or buried so
deeply that the original minerals in them are no
longer stable. These rocks then recrystallize
slowly (without melting) into new rock types
that have different minerals than those
originally present. These are called
metamorphic rocks. The rocks that underlie
Manhattan, Staten Island, and the Bronx are
metamorphic rocks.
Homework
Read Chap. 3 in Skinner and Murck.