Sections 2 & 3: Latitude and Longitude and Maps

Latitude The equator is an imaginary line that circles the Earth

halfway between the north and south poles. It separates the Earth into two equal halves – the northern hemisphere and the southern hemisphere.

Latitude is the distance, measured in degrees, north or south of the equator. These lines are horizontal, parallel, and never intersect.

The equator is 0 degrees latitude and the poles are 90 degrees latitude.

Locations north and south of the equator are referred to by degrees north latitude or degrees south latitude. The degrees are further broken down into minutes and seconds.

Latitude

Longitude The prime meridian is an imaginary line that runs

vertically from the North Pole through Greenwich, England, to the South Pole. This line separates east from west.

Longitude is the distance east or west of the prime meridian. These lines are vertical and never intersect, but the lines do meet at the poles.

Longitude is measured from 0 degrees to 180 degrees. The prime meridian is 0 degrees longitude. Points east or west of the prime meridian are referred to by degrees east longitude or degrees west longitude.

Unlike the equator, the prime meridian does not circle the Earth. The line of longitude on the opposite side of Earth from the prime meridian is 180 degrees longitude, call the International Date Line.

Longitude

Finding Locations Latitude is written first in a

coordinate set.

Latitude is given north or south of the equator. Longitude is given east or west of the prime meridian.

Examples: 30degrees N, 90degrees W = New Orleans, Louisiana

Coordinate Set

Time Zones Time is measured by tracking Earth’s movement

in relation to the Sun. Each day has 24 hours, so Earth is divided into 24 time zones.

Each time zone is 15 degrees of longitude wide and is 1 hour different from the zones beside it.

The United States has 6 different time zones. As you travel from east to west across the U.S., you lose an hour. Ex. 5 pm Eastern Time is 4 pm Central Time is 3 pm Mountain Time is 2 pm Pacific Time.

When you travel across the International Date Line, you gain or lose a whole day. If you travel west across the International Date Line, you move forward one day. If you travel east across the Line, you move back one calendar day. Ex: If you flew from Hawaii on a Friday, it would be Saturday when you landed in Australia.

Time Zones of the United States

International Date Line

On the handout find the continent using the following coordinates

60o N, 140o W : 20oN, 20oW : 20oS, 60oW : 40oS, 140oW : 50oN, 20oW : 80oS, 120oE :20oS, 20oE :0o, 80oE :

Maps Maps are models of Earth’s surface. The

most perfect map is a globe.

Maps are made as map projections. A map projection is made when points and lines on a globe’s surface are transferred onto paper.

There are three main types of map projections and all of them distort the shape of the landmasses of their areas.

Projections

Mercator Projections Mercator map projections are used

mainly on ship.

They project the correct shape of the continents, but the areas are distorted.

Longitude lines are projected as parallel, making the areas near the poles look much larger than they are.

Robinson Projections A Robinson

projection shows accurate continent shapes and more accurate land areas.

In this projection, the lines of longitude are curved as they are on a globe, which results in less distortion near the poles.

Conic Projection

Conic projections are made by projection points and lines from a globe onto a cone.

These are used to make maps of small area, like road maps weather maps.

Topographic MapsTopographic maps are detailed maps showing the elevations of hills and valleys of an area.• They use lines,

symbols, and colors to represent changes in elevation and features on Earth’s surface.

Each line that shows a different elevation is called a Contour Line

The spaces between the contour lines are the Contour Interval Not all contour lines are marked with the elevation. The ones that are labeled are called the index contours. You can determine the elevation of other lines by adding or subtracting the contour interval from the elevation on the index contour. Contour

Interval

Depression ContourThis is shown by contour lines with short lines coming from it hachures (the lines point in the direction of the depression)

Rules of Topographic Maps1.They never cross or touch!!!

2.When they are close together, it means that it is a steep elevation.

3. When they are far apart, it means it is flatter land

4. When the contour lines make a V shape, it means there is a river

Topographic Maps A topographic map shows the changes in elevation of

Earth’s surface. These maps show natural features and also cultural

features, such as roads, cities, and other structures built by people.

These maps are helpful when doing outdoor activities like hiking.

A contour line is a line on topo a map that connects points of equal elevation.

The difference in elevation between two side-by-side contour lines is the contour interval, which stays constant throughout a map.

Not all contour lines are marked with the elevation. The ones that are labeled are called the index contours. You can determine the elevation of other lines by adding or subtracting the contour interval from the elevation on the index contour.

Topo Maps

Map ScaleThe map scale is the relationship between the distances on the map and distances on Earth’s surface.

Example: A topo map has a scale that reads 1:80,000. This means that one unit on the map represents 80,000 units on land.

Map Legend A map legend explains what the symbols used

on the map mean. Examples of map symbols are Roads, Boundaries between counties, cities, states, buildings, etc

Map Series Topo maps are made to cover different amounts of

the Earth’s surface.

The map series includes maps that measure the same area of the surface.

Example: A series may include 7.5 minute maps. These cover 7.5 minutes of latitude by 7.5 minutes of longitude of Earth’s surface.

Side View of my Mountain

100 ft75 ft50 ft25 ft

Mountain on a

Topographic Map

The Geologic Time Scale It is generally accepted now that Earth is

about 4.6 billion years old.

The Geologic Time Scale By studying the characteristics of rocks and

the fossils within them geologists can begin to reconstruct Earth’s history

The Geologic Time Scale Geologic time scale is a record of Earth’s

history from 4.6 billion years ago to the present

Geologic Time In order to quantify such a vast amount of

time Earth’s long history is divided into specific units.

Geologic Time These units are not absolute dates but

records that increase or decrease in relation to each other based on the rock record and fossil data discovered.

Geologic Time The names of the periods do not change, but

the years marking the beginning and ending of each are continually being refined as more data become available

Eons An eon is the largest unit of time and is

measured in billions of years. There are four Eons in Earth’s History.

Eons Archean Eon spans 3.8 billion years to 2.5

billion years B.P.

Eons No fossils of any kind

Eons Proterozoic Eon spans 2.5 billion years to 540

million years BP

Eons Bacteria-like organisms form, several episodes

of mountain building

Eons Phanerozoic Eon spans from 540 million years

to present

Eons 90% OF Earth’s history falls in the Archean

and Proterozoic Eons. This is referred to as Precambrian Time.

Eras An era is the next longest span of time. It is

measured in hundreds of millions of years.

Eras Eras are defined by differences in life forms

found in rocks. There are three eras in the Phanerozoic Eon

Eras Paleozoic Era spans 540-245 million years BP

Eras The Paleozoic Era marked the dominance of

animal life in the oceans as plants began to take over the continents

Eras Mesozoic Era spans 245-66 million BP

Eras The Mesozoic Era marks the dominance of the

dinosaurs on land

Eras Cenozoic Era spans 66 million years to present

Eras The Cenozoic Era marks the dominance of

mammals

Periods Periods are defined by the life forms that were

abundant or became extinct at the time in which specific rocks were deposited. They are measured in tens of millions of years.

Periods The Paleozoic Era has 7 periods

Periods Cambrian- 540 MYBP, Marine Invertebrates

abundant

Periods Ordovician-510 MYBP, First fish appear

Periods Silurian- 439 MYBP, First land plants, first

insects

Periods Devonian- 408 MYBP, First amphibians

Periods Mississippian- 362 MYBP, Amphibians

dominant

Periods Pennsylvanian- 323 MYBP, Reptiles appear

Periods Permian- 290 MYBP, Reptiles evolve, coal

swamps

Periods The Mesozoic Era has 3 periods

Periods Triassic Period- 245 MYBP, Mammals appear

Periods Jurassic Period- 208 MYBP, Dinosaurs

dominant

Periods Cretaceous Period- 146 MYBP, Angiosperms

appear

Periods The Cenozoic Era has 3 periods

Periods Paleogene Period-66 MYBP, Early horses

Periods Neogene Period- 23 MYBP, Mammals

dominant

Periods Quaternary Period- 1.6 MYBP, Early Humans

appear

Epochs The fossil record of the Cenozoic Era is

complete enough to allow further more precise divisions.

Epochs The Paleogene Period has three epochs,

Paleocene (66), Eocene (56), and Oligocene (35)

Epochs The Neogene period has two epochs, Miocene

(23) and Pliocene (5)

Epochs The The Quarternary period has two epochs,

Pleistocene (1.6) and Holocene (0.01)

Clues to the Earth’s Past

Fossils

Paleontologists study fossils and reconstruct the appearance of animals.

B. Fossils—remains, imprints, or traces of prehistoric organisms

1. Fossils can form if the organism is quickly buried by sediments.

2. Organisms with hard parts are more likely to become fossils than organisms with soft parts.

C. Types of preservation1. Fossils in which spaces inside are filled with minerals from groundwater are called permineralized remains.

2. Carbon film results when a thin film or carbon residue forms a silhouette of the original organism; carbonized plant material becomes coal.

3. Mold—cavity in rock left when the hard parts of an organism decay

4. If sediments wash into a mold, they can form a cast of the original organism.

5. Occasionally original remains are preserved in a material such as amber, ice, or tar.

6. Trace fossils evidence of an organism’s activities

a. Can be footprints left in mud or sand that became stone

b. Can be trails or burrows made by worms and other animals

D. Index fossils —abundant, geographically widespread organisms that existed for relatively short periods of time

E. Fossils can reveal information about past land forms and climate.

F. Most fossils in Virginia are marine organisms indicating that the area has been covered by seawater in the past.

Relative Ages of Rocks A. Principle of superposition—process of

reading undisturbed rock layers

1. younger rocks in the top layers

2. oldest rocks in the bottom layer

B. How old something is in comparison with something else is its relative age.

1. The age of undisturbed rocks can be determined by examining layer sequences. 2. The age of disturbed rocks may have to be determined by fossils or other clues

C. Unconformities—gaps in rock layers 1. Angular unconformity—rock layers are

tilted and younger sediment layers are deposited horizontally on top of the eroded and tilted layers.

2. A layer of horizontal rock once exposed and eroded before younger rocks formed over it is called a disconformity. 3. Nonconformity—sedimentary rock forms over eroded metamorphic or igneous rock.

D. The same rock layers can be found in different locations; index fossils can be used to correlate those rock layers.

Absolute Ages of Rocks A. Absolute age—age, in years, of a rock or

other object; determined by properties of atoms

B. Unstable isotopes break down into other isotopes and particles in the process of radioactive decay.

1. The time it takes for half the atoms in an isotope to decay is the isotope’s half-life.

C. Calculating the absolute age of a rock using the ratio of parent isotope to daughter product and the half-life of the parent is called radiometric dating.

1. Potassium-argon dating is used to date ancient rocks millions of years old.

2. Carbon-14 dating is used to date bones, wood, and charcoal up to 75,000 years old.

3. Earth is about 4.5 billion years old; the oldest known rocks are about 3.96 billion years old.

D. Uniformitarianism—Earth processes occurring today are similar to those which occurred in the past