West Coast Expedition
July 20 - August 30, 2002
West Coast of North America

July 31, 2002

Log Entry: Today was sunny and bright--but also so windy and with such large seas that today's dive was cancelled. When the seas are large, the launch and especially the recovery of the ROV are difficult and we risk damaging or losing the vehicle. We spent the day hoping for calmer seas and deploying a wax-tipped rock-coring device over the side of the vessel. The corer is designed to smash into the quenched glassy top of a lava flow, shatter the glass and embed the broken glass fragments in a sticky wax that fills a group of small cones that project from the bottom of the corer. In the event that the corer falls over, additional wax tipped cones are arranged around the 227 kilograms of weight that give the lowered core the power to shatter the glass. Each core takes about 2 hours to collect, plus the time to steam to the next site. We have collected four samples during the day and plan to continue with additional sites. The glass samples recovered are small, but are usually large enough to analyze using micro-analytical techniques. The samples will be used to evaluate variations in lava compositions along the northern Gorda Ridge and to relate the compositions to the shape of the sampled volcanic landforms. We are still hopeful that we can dive tomorrow before we steam to Newport, Oregon, but the wind has not abated during the day and continues to blow at nearly 40 knots.

-- Dave Clague

jul_31 RockCrusherLaunch2-sm.jpg
In 40 knot winds, white caps are everywhere, spray blows off the wave-tops, and long streaks of foam are left behind after the waves break. Since the waves are being forced locally, they are quite close together and traveling as random crests rather than in predictable wave-trains. It makes launching the ROV, and even the rock-crusher (pictured here), exciting events.
jul_31 RockCrusherWork1-sm.jpg
Jenny, Jim, and Dave removing wax-tipped cones from the rock-crusher on the aft deck after recovery. It is a two hour round-trip for the gear through the 3000 meter water column to the bottom and back.
The deck shots sent back from this leg were taken by Sierra and Shana (Jenny wrote most of the captions).

Wax-tipped cones loaded with black volcanic glass from one deployment today. The wax will be melted off and the glass grains dried and mounted into thin sections for electron microprobe analysis.
Janet scraping critters off rocks from dive T455.


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