"Nature Guide Journal"

10 January 2001

Beachcombers who frequent the beach year 'round know that the winter winds that rattle windows also greatly affect the shoreline. Winds, and the spectacular waves they generate, create a number of attention-getting effects.

Storms and "high seas" (heavy ocean swells and choppy whitecaps) dislodge kelp and other life attached to shallow bottom and toss it on to the shore. Bull-whip kelp, growing up to 80' long or more during the summer, are often torn off the rocks and rolled by the heavy surf into giant tangles.

A snarled mass of bull-whip kelp may incorporate other kelp—or other items. Beachcombers often search among the wrack (organic material that washes up on the beach) for floats and other human artifacts that collect with the plants.

Microscopic organic material in the sea water strengthens the bubbles whipped up by the heavy surf, making foam. The same chemicals in the kelps that we use to stabilize puddings, toothpaste, and such, are also churned into the surf and helps to stabilize the sea foam.

Waves formed by the relatively gentle winds of summer push sand onto the face of the beach, forming a humped profile. The larger, more powerful waves driven by winter storms scour the sand off the beach and deposit the sediments in bars just outside the surf zone, forming a flatter beach profile.

The removal of much of the beach sand further exposes the foredune and cliff face to the pounding winter surf with it's load of battering driftwood, increasing the erosion of new sand and rocks from the cliff onto the beach. The sand's movement often also reveals gravel beds beneath.

The freshly washed gravel lures rock hounds seeking treasures—primarily various kinds of chalcedony, high-silica stones related to quartz. Chief among the quarry are agates and jasper.

Whereas quartz has visible crystals, agates and jasper are both microcrystalline (also called "cryptocrystalline"). Agates have such a high percentage of silica—the material we use to make glass—that light shines through them. While jasper doesn't have the right mix of minerals to pass light, it often sports rich or bright colors of red, green, or dark yellow.

Beachcombers also seek petrified wood among the exposed gravel. As wood petrifies, the original organic molecules of the tree are replaced by inorganic molecules in a fashion so precise that the original form and design of the wood is retained in the resultant rock.

The bare beaches and larger waves of winter require additional caution by beach walkers. High waves can easily overrun the entire beach at high tide: visit the winter beach on an out-going tide. Unusually high waves ("sneaker waves") can more readily wash over jetties and rocks: avoid walking on them. If a log is on the beach it's almost certain a wave carried it there—and a wave can easily move it again: stay off of driftwood and logs on the beach and stay away from driftwood and logs in the water.

For many hardy souls, combing the beach for the prizes winter draws from the sea's edge are worth the additional bundling and caution.