What are crop marks?

When places where people once lived are deserted,

they become overgrown.

RuinsCreative Commons License Mark Coleman via Compfight

Eventually they are buried.

What is underneath the soil

can affect how the crops above them grow.

Ditches dug into the ground fill up with soil over time.

Crops grow well in these place.

They grow higher and look greener.

These create ‘positive’ cropmarks.


Where there are walls, floors or foundations underneath,

there is a thinner layer of soil.

Crops don’t grow as well on top of this rubble.

This creates ‘negative’ cropmarks.

Positive and negative cropmarks can be seen best from the air.

RHB_UK_Harnhill-1672_LabelledCreative Commons License DART Project via Compfight

Please note this is not a photo of Rathdown
and is only here to show ‘cropmarks’ in the landscape.

Click on this LINK to read more about cropmarks.

Photographs of cropmarks taken from the air, in 1970

show that there was early settlement at Rathdown, to the North of Greystones.

You can read more about those photographs HERE


Click HERE to see for a project in which

you can create your own cropmarks. 


UPDATED to add: During the drought of Summer 2018

something very exciting happened.

The drought caused some cropmarks

which hadn’t been seen before

to become noticeable.

This happened near Newgrange in County Meath.

You can read about this HERE

The same thing is happening in the United Kingdom.

Look HERE to see what is happening in Wales

and HERE for more information and a good explanation

of how cropmarks are made.

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