today
8:30 a.m. Audubon Society Field Trip See Event Description
read >9 a.m. Arcata Farmers' Market Arcata Plaza
read >9:30 a.m. Discovery Walk: Unknown Waterfront See Event Description
read >9:30 a.m. Manila Dunes Restoration Manila Community Center
read >10 a.m. Manila Dunes Guided Walk Manila Community Center
read >10 a.m. Library Book Sale Humboldt County Library
read >10 a.m. Dia de los Muertos and Mexican Folk Art Sale Private Eureka home
read >10 a.m. Final Arcata Farmer's Market Arcata Farmers' Market (off the plaza)
read >11 a.m. Donlin Foreman Dance Workshop Dell'Arte
read >2 p.m. Humboldt Coastal Nature Center Draft Trails Plan Walk Stamps House
read >5 p.m. Bati Zado and Show Redwood Raks World Dance Studio
read >6 p.m. The Tumbleweeds Chapala Cafe
read >6 p.m. Ali Chaudhary (jazz duo) Libation
read >6:30 p.m. Not Evil, Just Wrong Humboldt Area Foundation
read >7 p.m. Guitar Stan (country) Old Town Coffee & Chocolates
read >8 p.m. Guitar Orchestra of Barcelona Arkley Center for the Performing Arts
read >8 p.m. Stones in His Pockets Arcata Playhouse
read >8 p.m. A Christmas Carol North Coast Repertory Theater
read >8 p.m. Donna Landry Swing Dance Moose Lodge
read >8 p.m. North Coast Wind Ensemble Fulkerson Recital Hall at HSU
read >8:30 p.m. The Last Minute Men (international) Cafe Mokka
read >9 p.m. Ian McFeron Band (folk rock) Six Rivers Brewery
read >9 p.m. The Michael Paul Band WAVE @ blue lake casino
read >9 p.m. The Generatorz (classic rock) Central Station Cocktail Lounge
read >9 p.m. Taxi Bear River Casino
read >9 p.m. VJ Itchie Fingaz Pearl Lounge
read >9 p.m. Jack Ruby Presents + Blue Street + Acufunkture (DIY rock) Jambalaya
read >9 p.m. 2nd Annual Scorpio Bash The Red Fox Tavern
read >10 p.m. Music by DJ Sidelines
read >10 p.m. DJ Icy Hot Aunty Mo's Lounge
read >10 p.m. Jemimah Puddleduck (rock) Humboldt Brews
read >10 p.m. White Manna + Midday Veil + The King Salmon Duo (rock) Jambalaya
read >11 p.m. Radio Moscow (psychadelic blues) + Mosquito Bandito (one-man surf/garage) The Alibi Lounge and Restaurant
read >previous columns
June 26, 2008
Alien Plants
Pampas grass (Cortaderia selloana).Photo by Don Garlick. Which are the ...
read >June 19, 2008
Our Mattole Canyon
Just west of Cape Mendocino there exists a submarine escarpment ...
read >June 12, 2008
An Excess of X
Human females possess two X chromosomes, whereas males have one ...
read >
Photos
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Areal photo of Humboldt's lagoons.
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Areal photo of Shelter Cove.
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Diagram by Don Garlick.
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Diagram by Don Garlick.
Lagoons and Beaches
By Don Garlick
Lagoons
Shelter Cove
Much of our coastal topography is generated by repeated slips on thrust faults like the one along the east shore of Big Lagoon. However, wave activity tends to straighten the coastline by eroding headlands and depositing sediments in bays. Wave energy is focused onto the headlands by the refraction of waves as they are slowed by shallowing water.
Refraction also explains why wave crests tend to parallel the beaches upon which they break. However, residual obliqueness causes waves to wash up and down in a zigzag fashion, thus moving sand along the beach. Sand obtained from the mouths of rivers is transported along beaches and eventually delivered into submarine canyons. The offset of the beach between Stone Lagoon and Big Lagoon reveals the southward migration of sand around a rocky promontory.
A lagoon forms when longshore drift extends a beach across a bay. If the bay is large, tidal currents tend to maintain a breach in the beach, such as the entrance to Humboldt Bay. Big Lagoon’s beach is occasionally breached by winter storms or shovel-wielding miscreants.
The seasonal growth and decay of beaches is interesting. I understand how large winter waves remove sand to deeper water, but the up-slope transport of sand by small summer waves eludes my understanding.
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