relative dating what is it ?. who dunit ? james hutton holyrood park edinburgh castle lets start...

RELATIVE DATINGRELATIVE DATING

What is it ?

Who Dunit ?Who Dunit ?

James HuttonJames Hutton

Holyrood ParkHolyrood ParkEdinburgh CastleEdinburgh Castle

Let’s start with the story of James Hutton, a wealthy farmer born in 1726. As a farmer, it brought him

into close contact with the land

James Hutton’s James Hutton’s RevelationRevelation

He was the first person to realise

that the Earth must have been very much older than the 6,000

years believed at that time

Hutton’s ImaginationHutton’s Imagination

Hutton was convinced that the lowlands of Scotland had been

made at a later time than the uplands, but he did not have any

proofUNTIL …

Siccar Point, Nr Siccar Point, Nr EdinburghEdinburgh

Whilst walking along the beach at Siccar

Point, he noticed that the pebbles had come

from the cliff – he now understood that the beach sand was

made from the eroding cliffs – that was a big leap of

imagination for its time

Hutton’s Story of Siccar Hutton’s Story of Siccar PointPoint

He then noticed around the corner from the beach that some gently dipping red sandstones were lying

on top of some grey-coloured upright layers

From his observations, he began to unravel the story of what had happened to these

rocks

RELATIVE DATING RELATIVE DATING PRACTICALPRACTICAL

So, what is Hutton’s So, what is Hutton’s Story ? Story ?

The grey-coloured beds (A) were laid down as horizontal

layers of soft muds in the sea.

AThese were

hardened into rock deep in the Earth and then buckled

into folds by immense stresses.

So, what is Hutton’s So, what is Hutton’s Story ? Story ?

These stresses also thrust the rocks up to the surface as great mountains, which were then

eroded.

A These mountains were likewise worn down, and formed the horizontal red beds (B) on top of the vertical grey

rocks.

B

So, what is Hutton’s Story ? So, what is Hutton’s Story ? What is his evidence?

Fragments of the folded grey rock (A) are found in the red beds above it (B) –

so the red beds must be younger.

B

A

A

A

A

A

He didn’t even need fossils to date his beds !

Fold ShapeFold ShapeANTICLINE

younger

older

SYNCLINE

younger

older

What do you What do you think produces think produces

folds ?folds ?