Blood of stone

Awaiting the rain. Petrichor.
The ground and stones and earth need more
Moisture which threatens, to unlock,
Scented senses within the rock.
Imprisoned long and here throughout
The endless days of summer drought.
Until such time as clouds are rent
Petrichor closely guards its scent.

Blood of the stone’ it once was called.
The Greeks knew it well, so I’m told.
Although we’d known it all our lives -
Yet - never known - the word describes
A chemical called Geosmin,
Sensed in five parts per trillion.
Absolving dry and hard terrain
Till moistened by the quenching rain.

So, it seems, only once a year,
Can we breathe such fragrant odour.
And thankful for the days of sun;
Ever the more now they have gone.
Coming fresh precipitation,
Eager with anticipation.
Rain obeying some natural law
Will now release sweet petrichor.

North Devon, July 2018