Portlandian Limeston: Always the Bridesmaid?

August 9, 2017

Welcome to #SciFri!

This week, our musings on Portlandian Limestone…. #TheDirt: So why is Portlandian limestone (deposited in the Portlandian age, 146-142 million years ago) considered the inferior little brother of Kimmeridgian limestone when it comes to wine?? For rock talk, we always consult our Master Geologist, Brenna Quigley.

Portlandian and Kimmeridgian Limestones

“Portlandian (left) rocks are harder than Kimmeridgian (right) stones, and form the steep, resistant ridges of the plateaus above Chablis. Portlandian rocks are described as shattering due to frost (water seeps into cracks, freezes and expands, breaking the rock), creating angular gravels that cover the Kimmeridgian slopes. Kimmeridgian stones are softer and easy to work. They also have a higher water holding capacity so the vines get just enough of what they need.

“It is also important to note that the change from Kimmeridgian to Portlandian is a very transitional one, and can occur over a distance of several meters. Even geologists cannot always agree on clear boundaries between the two–hence some of the arguments over what counts as true Chablis, true grand cru, etc.”

Tune in each week for more factoids from The Source on #VineLife #TheDirt and #CellarRat.