history of plate tectonic theory🥀🙏🙏

what is ‘‘Plate Tectonics’’

scientific theory that lithosphere = broken up into 13 plate that move independently weaker asthenosphere

Alfred Wegener

originator of continental drift hypothesis by suggesting in 1912 that continents = slowly move around Earth.

Alfred Wegener evidence

1. Fossil Evidence:

200 mill yrs ago fossil of plant + animal found in South America + Africa + South America + India + Aus ( - long time ago same plants + animals live on continents that = far away today.
- shows continents used to be together)

Alfred wegener evidence

2. Mountains - in North America and Africa, mountains = have been part of the same mountain range.

They match up!

Alfred Wegener evidence

3. Coal deposits:

There = coal deposits on Arctic Circle continents - which are now too cold to grow forests

Alfred Wegener evidence

4. Glacial scars:
On continents too warm to produce glaciers, there is evidence of glacial scarring

Alfred Wegener evidence

5. Magnetic volcanic rocks:

when new rocks formed from magma - magnetic minerals align w north/south poles / when continents joined - magnetic alignment of rock point to north

Gondwana & Aus

Aus separate from Gondwanaland 40 mill yrs ago. Aus = isolated biologically - result in evolution of unique plants + animal to suit Aus environment

Australian flora + fauna

Flora + fauna from other continents Aus been connected to still share some similar qualities 

Wegener

W idea = controversial bc he ❌ have explanation y continent move - There were only observational evidence they had

geologist beleifs

many geologists believe features of the Earth = result of Earth go thru cycles of heating + cooling, which cause expansion and contraction of land masses - ❌ think continent move - •Ppl who believe this = called anti-mobilists. 

mobilists

mobilists = in opposite camp + support Wegener's ideas, since many of them = seen evidence for continental motion, especially in Alps

scientist of diff discipline

Scientists of various disciplines had differing opinions on what may have occurred in the late 16^th century

• A cartographer thought the Americas were torn away(North and South America got separated from Europe and Africa.)
   from Europe and Africa by earthquakes and floods.

• A naturalist(A person who studies plants, animals, and nature.) believe land sank between continents, making Atlantic Ocean

• A geographer made theory tht initially there was a single continent by studying the shape of the continents and location and types of fossils

development of plate tectonic theory

Bathymetric surveys unveiled extensive submarine mountain ridge the length of the Atlantic Ocean, between the continents

development of plate tectonic theory

Seismic data began reveal Earth’s layers, a core, + crust-mantle boundary, + thick outer layer called the lithosphere that = above a less-dense asthenosphere.