There's no better place for a geology buff in summer than a shingle beach. Seriously. Everyone else can keep their sweeps of pristine sand covered in sunbathing humans. If you've got a rock lover in the family, or if you yourself are enamored with everything from pebbles to batholiths, you've really got to get yourself to a shingle beach this summer.
How do you know you've got a shingle beach?
Have a close look at the beach. Is it mostly sand? Not a shingle beach, then. Has it got lots and lots of rocks, anywhere from 4 millimeters to around 256 millimeters around? Then congratulations! It's shingle! And if, like me, you grew up reading British literature but were confused by what the heck they were talking about when they were walking across the shingle on the beach, you can now happily put that mystery away as solved. Go pick your way across the shingle like many of your favorite characters. Maybe you'll even bathe in the water - that's swim, for American folk.
All I've got is boring sand. Where can I find shingles instead?
Most shingle beaches are in higher latitudes that were covered by ice sheets and glaciers in the Pleistocene. You'll find them on coasts where the bluffs and cliffs are made up of glacial and fluvioglacial deposits like till and outwash. You'll also find them where rivers are delivering large payloads of rock to the coasts, or where the rocky cliffs are being converted to cobbles and pebbles by wave action.
Remember: high latitudes aren't restricted to the Northern Hemisphere. The Southern Hemisphere has got them, too. If you're not lucky enough to live in high latitudes, shingle beaches are going to be rare. But don't worry! You can still find some. Even on coral atolls, you can get some pretty nice coral shingle on the side facing the sea, while getting those lovely coral sand beaches on the lagoon-facing side. Best of both worlds right there!
Don't forget that shingle beaches aren't restricted to marine coasts: there can be marvelous shingle beaches along lake and river shores, too.
You can find your nearest shingle beach by searching "shingle beaches near X" or "pebble beaches near X." I don't advise searching "Shingles near X" since that will return results quite different from what you're after. It could be useful if you need to get a shingles shot, though: you could have a shingle-themed day.
What are shingle beaches made of?
You can find all sorts of rocks on a shingle beach! Mostly, they'll be made up of rocks resistant to erosion. What, exactly, will depend on the country rock and what the glaciers dragged in. You'll find hard corals on a coral atoll. You'll find things like flint around chalky cliffs such as Dover. Really well-cemented sandstones can survive all the waves throw at them. You can find lots of lovely metamorphic rocks in places like Washington State. Even semi-precious gemstones like agate and jasper.
Many shingle beaches are composed of a variety of rocks, but some are dominated by only one type. One of my favorite beaches, Black Pebble Beach at Yaquina Head in Oregon, is made entirely of basalt.
Other than rocks, what should I look at on a shingle beach?
Look for ridges! Most shingle beaches have ridges at different points. There's one at the top, where the strongest storm waves reach. And then there are smaller ones marking smaller storms or high tide. Then there's often a terrace marking low tide levels. You may also notice that most of the shingle is high up on the beach, while there's more sand near the water: more vigorous waves toss rocks up higher, while more languid ones are capable of ushering sand around.
Walk along the beach and note the sizes of the rocks: sometimes, you can tell the direction of the waves from the size of the cobbles or pebbles. Vigorous waves carry larger cobbles, and as their energy dissipates, smaller stones are dropped. Some beaches don't show much variation, as the waves hit them pretty straight on. Others will show a marked gradation, going from teeny tiny pebbles up to large cobbles. If you know such a shingle beach well, you'd be able to tell where you were on it just by feeling the rocks.
You can also look round for rare plants and animals, some of which are only found in these very challenging environments.
What are some geektastic facts about shingle beaches?
Mixed sand and shingle beaches might become really important with global warming and rising sea levels, since they're really super good at dissipating wave energy: they can do that to up to 90% of that energy.
Of course, they can be eroded, sometimes severely, if the water levels are high enough and the storm waves powerful enough, so it remains to be seen just what kind of coastal armor they can provide in an era of higher sea levels and powerful storms. But it's for sure they'll fare better than plain ol' sand.
Also, they can be steeper than sand beaches. Sand just can't achieve the same gradient!
Now you've got all the facts you could want. Go find yourself a shingle beach. And if you're really, really lucky, you'll be there on a day when the waves are making the most lovely sounds as they rattle all those delightful rocks.
Here's a longer video if you just couldn't get enough.
Agassiz, Alexander: The Coral Reefs of the Tropical Pacific, Volume 28, Part 1
King, C.A.M.: Shingle and shingle beaches
Liverpool Hope University: Shingle
Watt, T. and Moses, C: Modeling the Behavior of Shingle Beaches: A Review