Parch Marks

For most of the summer, many of us have been suffering through a horrible drought (it broke here in Baltimore over the weekend with 6+ inches of rain since Saturday!), but it’s still going strong in the UK. This drought has uncovered a trove of information, much previously unknown. Appearing in the grass and on the lawns of many historic sites are what is known as parch marks. These marks are the remnants of what existed in the space in the past.

In this garden at the historic house, Hardwick Hall, you can make out the original garden design with the original design just below.

Here’s a general explanation of parch marks, or as they’re sometimes called, crop marks:

Crop marks appear due to the principle of differential growth. One of the factors controlling the growth of vegetation is the condition of the soil. A buried stone wall, for example, will affect crop growth above it, as its presence channels water away from its area and occupies the space of the more fertile soil. Conversely, a buried ditch, with a fill containing more organic matter than the natural earth, provides much more conducive conditions and water will naturally collect there, nourishing the plants growing above.

The differences in conditions will cause some plants to grow more strongly and therefore taller, and others less strongly and therefore shorter. Some species will also react through differential ripening of their fruits or their overall colour.

Here are some additional images that which have been discovered over the past few weeks in the UK. In the UK, the big drought in 1976 revealed many unknown sites,  but many of these parch marks are only being found now because of the availability of drone photography which provides the perspective needed to see the marks.

Gawthorpe Hall, Lancashire

This house at Clumber Park was demolished in 1938, but the outline is now showing.

The outlines of a former circular garden at Knole.

WWI Trenches in Kent

Outlines on the lawn at Chatsworth (still peeved that I couldn’t visit)

A newly discovered henge in County Meath, Ireland

Remains of a former RAF airbase in Hampshire.

Parch marks of a large prehistoric enclosure in Wales' Vale of Glamorgan (where I used to live), with the faint footings of a probable Roman villa

The remains of a Roman town in Norfolk.

WWII air-raid shelters in Cambridge

Although the drought is not a good thing, it’s certainly fascinating what it has been revealing!