Meteorologically speaking, summer is typically a quiet time at the beach. Early fall hurricanes or winter storms commonly churn up the sand and pull it out to sea. Vacation season often coincides with relatively calm surf.
But a confluence of factors has given the beach along much of Maryland's Atlantic shore an unusual profile for its busiest time of year: It's marked by a ledge of sand as high as 4 feet.
Kevin Permison, who has spent the past five days in Ocean City, is 5 feet 11 inches tall.
"It was kind of a leap for me," the Lutherville man said, and it made it tough for his 69-year-old mother to get to the water: "She had to have guys help her down the wall because it was that high."
It's not an unusual feature for the state's premier beach, Ocean City officials say — it's just rare for this time of year. They blame a full moon, frequent, steep and ill-timed waves and, possibly, warmer-than-normal waters for eating away a chunk of the beach last week in just a matter of hours.
"The sand gets almost vertical because of the way it chews it away," said Terry McGean, the city engineer. "It's a very visually noticeable change in the beach."
But that's not to say it's alarming. It's common for much of the rest of the year — when the shore isn't packed with sunbathers and bodysurfers. After major storms — superstorm Sandy is a recent example — the cliffs of sand can be even higher.
"It's something that happens pretty frequently in the winter and the spring," McGean said. "It's a natural occurrence."
Beachgoers began noticing the unusual cut in the sand a few days before the last full moon, July 31, said Butch Arbin, captain of the Ocean City Beach Patrol.
It was a blue moon — the second full moon that month — but that didn't give it any greater influence over tides.
What made the full moon different was its timing — it coincided with lunar perigee, the point in the moon's elliptical orbit when it comes closest to Earth. On Aug. 2, the moon came within about 225,000 miles of Earth, its closest since April and about 13,000 miles closer than average. That made high tides extra high and low tides unusually low.
The next night, McGean observed, high tide coincided with a six-hour period of frequent, powerful waves. National Oceanic and Atmospheric Administration buoys recorded a period of "very steep" waves.
"It's the difference between a force being applied kind of gradually or the force being applied very quickly," he said. "Instead of a slow erosion and a nice, gradual slope, it erodes the sand in a very short burst."
Arbin says the unusually warm summer waters of the Gulf Stream — which have been blamed for increased shark sightings along the southern Atlantic coast — might also have been a factor. The warm water can change the direction of currents, which can affect wave action.
Low pressure moving across the Carolinas over the weekend is expected to stir waves in Ocean City as high as 5 feet and bring in strong winds from the northeast. Lyle Alexander, a meteorologist with the National Weather Service in Wakefield, Va., said the pattern is more common in winter.
The beach erosion hasn't created any significant hazards, McGean said — if anything, it's made for a more gradual slope for waves to crash onto. The beach patrol issued warnings against digging tunnels or holes more than knee-deep that could collapse.
Many beachgoers have taken advantage of the drop-off, Permison says, parking their blankets and umbrellas closer to the water than they might otherwise, the cliff protecting them from the surge of high-tide waves.
The erosion didn't faze Blair Rhodes, owner of Chauncey's Surf Shop in Ocean City.
"That's just Mother Nature; it's a constantly changing bottom," Rhodes said. "In the summer we usually don't have any waves. The waves haven't been epic this summer, but there's been at least something to ride every day."
Early August is among the busiest periods for Ocean City. It hosted the White Marlin Open fishing tournament this week, and families are squeezing in a vacation before schools reopen.
For the beach patrol, this summer has been quieter than last, when three people drowned and lifeguards summoned ambulances an average of more than once a day.
"It's been a pretty uneventful summer," Arbin said. "Last summer was an anomaly with some of the things that happened here. This is more of a typical summer."
It could stay that way — McGean said the erosion isn't nearly enough to trigger a need to pump more sand onto the beach. Engineers last rebuilt Ocean City's beaches last year, and they aren't scheduled to do so again until 2018.
"In two weeks, the beach will look completely different than it does now," McGean said. "It's just a dynamic process out there.
"This is one of those things that looked worse than it really is."