10th January 2008 - Half Moon Island and Drake Passage North
Time: 05:23, 62 degrees 34.93' South, 59 degrees 44.35' West, overcast but dry, fog and mist later on the Drake Passage, Wind North East 0-2 at first picking up a bit on the Drake, Air Temperature 5.0 oC, Water Temperature 1.3 0C, Sunrise 4.28am, Sunset 11.53pm.
Preparing to leave Half Moon after a successful Landing.
Today we made our first successful complete passenger landing at Half Moon Island. Skies were grey but it was dry and the winds were light. The Chinstrap Penguins are much more vocal than the Gentoos we had been seeing. The would regularly all start pointing their beaks to the sky and make loud guttural sounds while flapping their stiff wings slowly.
A Chinstrap Penguin high on the top of Half Moon Island, Livingstone Island in the background.
A Chinstrap deciding which way to go.
Skuas would frequently patrol the rookery, landing on a prominent rock and looking for a vulnerable nest. While we were there one skua snatched a penguin chick and eat it in the snow. People say this is cruel but unlike humans they are not doing it "for fun" or revenge. They are essential for maintaining the penguin rookery in a healthy state and without them and other predators/scavengers the whole antarctic ecosystem would eventually collapse. If you do find things like this in nature upsetting it is best to think of it as a necessary evil and resist to cast them as "baddies" in a human way. After our successful landing we headed for the Drake Passage. Once again, a few miles off King George Island we passed through the armada of huge icebergs strung out on the sea in a line running roughly northeast to south west. 
A deep blue iceberg in Darke Passage.
We picked up our usual escort of Cape Petrels as we headed out into Drake Passage. Thanks to everyone checking out the blog, especially passengers who joined us on earlier cruises. I hope the schools back home are finding it interesting. Once again sorry I cannot reply to you individually.
Continuing his geological notes on the day I hand you over to Tom Sharpe.
Tom - Another Great Geology Day today! It was a bit of an early rise, though. We had to be ready to go at 6am, and getting into the zodiac was fun, with a sea swell taking the zodiac up and down. But it was worth it. We were at Half Moon Island which is shaped like the letter C. It’s a spectacular setting, close to the northeast coast of Livingston Island in the South Shetland Islands. Livingston’s mountains and glaciers tower over Half Moon.
Picture 1: Half Moon Island with the mountains of Livingston Island behind.
(photo Tom Sharpe)
Half Moon Island is only about 2 km across, but it has some great geology. It was once three separate small, rocky islands which are now joined up by pebble beaches. Sea currents coming in around the side of Livingston Island probably swept the pebbles along from island to island, eventually linking them together to form Half Moon. The bits that were once islands now form rocky hills.
Picture 2: Half Moon Island (photo Tom Sharpe)
As at our other sites this week, I found different kinds of lavas, and rocks like granite from different parts of the island. Again, these are mostly about 100 million years old.
Picture 3: Pinnacle of rock on Half Moon Island (photo Tom Sharpe)
Some of the rocks made interesting features. In the Chinstrap penguin rookery in the southwest arm of Half Moon Island there are pinnacles of rock sticking up, and there is another one down near the shore. Because the penguins were in the way I couldn’t get a close look at the rocks, but from the shape of the pinnacles I think there were made of vertical sheets of lava-like rock that solidified in cracks. Geologists call these features dykes (or dikes in American).
Picture 4: Dyke of igneous rock on Half Moon Island (photo Tom Sharpe)
Just as we were getting ready to head back to the ship, David, our Expedition historian, showed me some interesting-looking stones on the rocky ridge near where he had been standing. They weren’t like any of the other rocks I had seen on Half Moon. They were clusters of brown and red pebbles in amongst the usual grey rocks. Some looked like pieces of brown lava with gas bubbles, and others were red pebbles of quartz. Quartz is the commonest mineral on Earth. It is made of silica, which is the same stuff as the sand on beaches. It’s usually white or clear, but it can be coloured red if there is iron around.
Picture 5: Cluster of brown pebbles on Half Moon Island (Photo Tom Sharpe)
The pebbles were small and round, like the pebbles on a beach. But they were high up on the island. They must have been deposited when sea level was a lot higher than it is now (or maybe the island was lower). But why they were in clusters is a bit of a puzzle.
I didn’t have time to examine them closely, but we should be back on Half Moon Island again, if the conditions allow, and I plan to look at them again.
After leaving Half Moon Island we sailed past Greenwich Island and through the Nelson Strait between Robert Island and Nelson Island. Like the rest of the South Shetland Islands, these islands are mostly covered in ice, with a few rocky bits along the coast.
We had a great view of the coast of the Fildes Peninsula at the southwest tip of King George Island. It’s a spectacular craggy coastline, with big lumps of rocks sticking up. They are made of lavas and other volcanic rocks about 50 million years old.
Picture 6: Large iceberg passing our ship. (Photo Tom Sharpe)
Just as the coast of King George Island faded into the distance, we sailed through a column of big icebergs which lay across our route. Most of them were bigger than our ship.
Now we’re back into the Drake Passage, one of the roughest stretches of sea in the world. Here’s hoping for a smoother crossing than last time back to Ushuaia. No more rocks for me until we reach Cape Horn sometime tomorrow.
Wildlife seen at Half Moon Island and Cruising North on Drake Passage
Mammals
Humpback Whale 10
Minke Whale 2
Weddell Seal 2
Fur Seal 1
Birds
Giant Petrel 20+
Black-browed Albatross 9
Southern Fulmar 2
Cape Petrel 28
Antarctic Prion 10+
White-chinned Petrel 11
Wilson’s Storm Petrel 100+
Chinstrap Penguin 1,000+
Snowy Sheathbill 5
Antarctic Shag 8
Brown Skua 20+
South Polar Skua 9
Antarctic Tern 40+
Kelp Gull 10+
Note: A + sign after the counts indicates that we saw at least that number but more may have been present.
Time: 22:12, 60 degrees 20.96' South, 61 degrees 53.90' West, Air Temperature 9 oC, Water Temperature 1.9 0C, fog and mist, light sea swell, Wind Northeast force 3-5.
