Plunging chevron folds at Northcott Mouth

Bedding traces of plunging chevron folds in the Bude Formation (upper Carboniferous) sandstones in the beach at Northcott Mouth, near Bude, north Cornwall. Two faults cut the bedding traces in the lower right quadrant. Synclines 'V' towards the camera; anticlines 'V' towards the sea. The plunge is seawards.

What does this mean?
Here's a simple model - fold a sheet of thin card into a few zig-zag folds so it becomes angularly corrugated like a fan. Open the card out a little and hold it horizontally. Look along the length of the folds. That's the situation with no plunge. Now, tilt the card slightly downwards at the far end, still continuing to look down the length of the folds. The tilt you have applied is the 'plunge' of the fold set.

Now, keeping that same gentle angle of tilt, partially immerse the folded, tilted card into a bowl of water. Quickly, before it gets too soggy and distorts, notice the pattern of the water-line where the card intersects the water surface: a series of elongated zig-zags just like these on the flat surface of the beach. The steeper the angle of plunge, the shorter the elongation and vice versa.