Some of the water originates as rain that flows into streams on impervious rocks on the plateau before sinking at the limestone boundary into cave systems such as Swildon's Hole, Eastwater Cavern and St Cuthbert's Swallet; the remainder is rain that percolates directly through the limestone.
He tells us that his people are cast by Westerners as "living on the perfume of the lotus, if not on mice and cockroaches," and are thought to be more or less impervious to pain on account of their fatalistic natures.
"Demand for health care is impervious to the goings-on in the economy".
No matter that the United States has been mostly impervious to attacks on its soil: "American settlers' vulnerability is "our founding trauma".
Since early this year, the familiar grooves of Senator Barack Obama's battle with Senator Hillary Rodham Clinton have appeared all but impervious to events on the campaign trail.
Like others of his ilk that I have encountered over the years, the claimant, a church organist, is a courteous, highly intelligent, learned and apparently rational man who is nevertheless impervious to reason on the topic that obsesses him and to which he has misguidedly devoted years of intellectual effort.
Pictures, tweets, and posts live on impervious to their future impact.
GROWTH may have returned at long last to the American economy, but the housing crisis which set the recession in motion rolls on, impervious to government fixes.
For example, about 21,000 property owners in the city of Portland, Maine are being charged a new fee that is based on the amount of hard or impervious surface on their property.
It's impossible to remain impervious to what's going on around her, no matter how she tries to seem otherwise.
