Blame, now. There is a nasty black bog if ever there was one. - Stephen R. Lawhead

And then, just as I begin to raise my sword to cleave a path to Arthur's side, there comes a sound like a tempest wind - the blast of a mighty sea gale. Men fall back, suddenly afraid. They cover their heads with their arms and peer into the darkness above. What is it? Is the roof falling? The sky?
The strange sound subsides and they glance at one another in fear and awe. Merlin is there. The Emrys is standing calmly beside Arthur. His hands are empty and upraised, his face stern in the unnatural silence he has created . . .

If her hunch was right, the earl’s explorations were connected in some way to ley travel: that peculiar phenomenon that had plucked her from the twenty-first century and dropped her so rudely into the seventeenth.

The path is revealed in the treading.