Standard 1.h: Read and interpret topographic and geologic maps.

Mapping Our World

• In order to find locations on Earth, cartographers have created an imaginary grid of parallel lines and vertical lines.

• The equator is an imaginary line that circles Earth halfway between the north and south poles.

Understanding Maps

• This separates Earth into two hemispheres:

1. Northern Hemisphere

2. Southern Hemisphere

• Imaginary lines that run parallel to the equator

• The distance in degrees North or South of the equator

Latitude

Measured from 0° at the

equator to 90° at the poles

• Locations north of the equator are referred to by degrees north latitude (N).

• Locations south of the equator are referred to by degrees south latitude (S).

North Latitude is

located North of the

Equator

South Latitude is

located South of the

Equator

Degrees of Latitude

– Each degree of latitude is equivalent to about 111 km on Earth’s surface.

– To locate positions on Earth more precisely, cartographers break down degrees of latitude into 60 smaller units, called minutes (´).

– A minute of latitude can be further divided into 60 seconds (´´).

– Longitude is also divided into degrees, minutes, and seconds.

1° = 111 km (69 miles)

• Also known as meridians. • Distance in degrees east or west of the

prime meridian.

Longitude

The prime meridian,

representing 0° longitude, is the

reference point for longitude.

• The Prime Meridian divides Earth into East and West Hemispheres

• Points west of the prime meridian are numbered from 0° to 180° west longitude (W).

• Points east of the prime meridian are numbered from 0° to 180° east longitude (E).

(Runs through Greenwich, England)

• Longitude lines are not parallel; they are large semicircles that extend vertically from pole to pole.

• Distances covered by degrees of longitude vary with location.

• One degree of longitude varies from about 111 km at the equator to essentially the distance covered by a point at the poles.

– Both latitude and longitude are needed to precisely locate positions on Earth.

– For example, the location of New Orleans is 29°57´N, 90°04´W.

– Latitude always is written first.

Locating Places with Coordinates