OCEANS 100 SDSU LAB PRACTICAL 1 QUESTIONS AND
ANSWERS
What happens in a Mercator map projection (in regards to latitude and longitude)? - -
Places at higher and lower latitudes are exaggerated and look as if they are bigger than
they really are
-Seasonal variations in sunlight why does this happen? - -Summer and Winter Solstices
differences in each hemisphere. Earth tilts on its axis (consistently 23.5), causing the
Northern / Southern hemispheres trade places throughout the year in receiving the sun's
light and warmth most directly. Seasons in the southern hemisphere occur at opposite
times of the year from those in the northern hemisphere. Northern summer = southern
winter.
-Know the differences between latitude and longitude; what they are used for; major
lat/long reference points. (i.e. Equator/ Prime Meridian/ etc.) - -Latitude - One's north-
south position with the equator defined as 0 degrees and geographic poles defined as 90
degrees N and 90 degrees S. Longitude - One's east-west position, Prime Meridian is
defined by 0 degrees longitude. All other longitudinal values are defined by the angle that
their plane forms with that of the Prime Meridian. International date line - Longitude line
opposite of the Prime Meridian defined as 180 degrees
-Using data from a sextant and chronometer calculate latitude and longitude (Part B1) - -
Sextant - device used to determine one's latitude, measures the angle between the horizon
and one of two stars located directly above the Earth's axis of rotation (North star or
Southern Cross). Chronometer - accurate clock set to UTC (time at 0 degrees longitude)
Earth rotates at 15 degrees per hour ( hours in a day). To find if you are east or
west of Prime Meridian, if you are earlier than UTC time, you are to the west. Calculating:
Sextant - same as latitude. Longitude - multiply the number of hours from 1200 by 15
-Be able to distinguish different types of plate boundaries and their motion on a map.
Calculate average seafloor spreading rates. (Part B) - -Seafloor spreading rates : distance
(cm) / oldest crust age (yr)
-Understand fracture zones vs transform faults; seafloor spreading and relative plate
motion (Part D) relationship between divergent and transform plate boundaries w/in
oceanic lithosphere. - -The relationship arises due to the rigid nature of the lithosphere
and the spherical shape of the earth.
-Transform fault - -forms at the offset between the two ridges.
-Fracture zones - -a linear oceanic feature—often hundreds, even thousands of kilometers
long—resulting from the action of offset mid-ocean ridge axis segments, extend past the
transform faults, away from the ridge axis; seismically inactive
ANSWERS
What happens in a Mercator map projection (in regards to latitude and longitude)? - -
Places at higher and lower latitudes are exaggerated and look as if they are bigger than
they really are
-Seasonal variations in sunlight why does this happen? - -Summer and Winter Solstices
differences in each hemisphere. Earth tilts on its axis (consistently 23.5), causing the
Northern / Southern hemispheres trade places throughout the year in receiving the sun's
light and warmth most directly. Seasons in the southern hemisphere occur at opposite
times of the year from those in the northern hemisphere. Northern summer = southern
winter.
-Know the differences between latitude and longitude; what they are used for; major
lat/long reference points. (i.e. Equator/ Prime Meridian/ etc.) - -Latitude - One's north-
south position with the equator defined as 0 degrees and geographic poles defined as 90
degrees N and 90 degrees S. Longitude - One's east-west position, Prime Meridian is
defined by 0 degrees longitude. All other longitudinal values are defined by the angle that
their plane forms with that of the Prime Meridian. International date line - Longitude line
opposite of the Prime Meridian defined as 180 degrees
-Using data from a sextant and chronometer calculate latitude and longitude (Part B1) - -
Sextant - device used to determine one's latitude, measures the angle between the horizon
and one of two stars located directly above the Earth's axis of rotation (North star or
Southern Cross). Chronometer - accurate clock set to UTC (time at 0 degrees longitude)
Earth rotates at 15 degrees per hour ( hours in a day). To find if you are east or
west of Prime Meridian, if you are earlier than UTC time, you are to the west. Calculating:
Sextant - same as latitude. Longitude - multiply the number of hours from 1200 by 15
-Be able to distinguish different types of plate boundaries and their motion on a map.
Calculate average seafloor spreading rates. (Part B) - -Seafloor spreading rates : distance
(cm) / oldest crust age (yr)
-Understand fracture zones vs transform faults; seafloor spreading and relative plate
motion (Part D) relationship between divergent and transform plate boundaries w/in
oceanic lithosphere. - -The relationship arises due to the rigid nature of the lithosphere
and the spherical shape of the earth.
-Transform fault - -forms at the offset between the two ridges.
-Fracture zones - -a linear oceanic feature—often hundreds, even thousands of kilometers
long—resulting from the action of offset mid-ocean ridge axis segments, extend past the
transform faults, away from the ridge axis; seismically inactive
