Prologue: History of Oceanography

Objectives:• Know about ocean exploration • Understand the major events in

oceanography• Be able to define oceanography and tell the

disciplines within

Disciplines within Oceanography

• Define oceanography.• Geological oceanography• Physical oceanography• Marine meteorology• Chemical oceanography• Biological oceanography• Ocean engineering

HISTORY • Why did man first want to study the ocean? Early History:• How was 1st knowledge of the sea passed on?• 5000 Bcà copper fish hooks/fishnets • ~2800 BC à trade in the Mediterranean• ~1500 BC à Phoenicians

– Extensive trade, used landmarks for reference– By 600 BC Phoenicians had circumnavigated africa– used movement of sun– named directions: Asu, Ereb– at night, used stars for navigation

History, cont.• 1500-500 BC: Arab traiders in Indian

Ocean• 900-700 BC: Greeks navigating by land

– First cartographers“Oceanus”

• Same time: Chinese navigating by sun/stars– First compass

History cont3rd century BC: Library of Alexandria

built by?• Eratosthenes measured circumference of

world = 40,230km; modern = 40,067• Latitude and longitude established• Ptolemy: 1st atlas

– Changed circumference; overestimated Asia, underestimated ocean; no knowledge of American continent

History, cont.

What happened to the Library ? Why?

Dark Ages:• Astrolabe used • Sextant

– T-shaped device, measured ht of sun/stars using horizon

• 1187 **1st compass used (why did the sailors not like the compass?)

• Ship building continued to improve

Dark Ages, cont.• 700-1000 AD: Vikings

**Colonized Iceland**Newfoundland (Leif Erikson)**Greenland (Eric the Red)**How did they navigate?– Starved ravens “straight as the crow flies”– N. Atl. Gyre current– seabirds

**Raids: European coasts and the near east (Constantinople)

• Arabs: access to greek and roman knowledge

**first to notice reversing of currents

• Chinese– junks – used charts– studied tides and salinity

Polynesians**charts made of . . .**sidereal compass

**sea lanes** other means of navigation**Why did they spread over

Pacific?**Double hulled ships

Importance of Charts and Navigation Information

• Latitude: how to determine?• Longitude:

**needed accurate clock for ships**Britain offered reward**Harrison’s chronometer**how to determine longitude?