Author: More than a Dodo

What’s on the van? – Sunset moth

This week’s What’s on the van? comes from Katherine Child, of the Museum’s Hope Entomological Collections.

This striking image shows the underside of a large tropical moth belonging to the family Uraniidae. Its scientific name is Alcidia boops, but it’s also known as a sunset moth due to its striking, shimmery colours. Unlike most moths, this species is active during the day. As the light shifts on the insect’s wings you can see the iridescent scales which act as a warning to predators. These bright colours advertise the fact that the creature is toxic and would not be a tasty mouthful.

Not only is the specimen pictured very beautiful, it is also extremely important. It’s one of almost 4000 butterflies and moths which form the museum’s Lepidoptera Type collection.  A type specimen is the designated individual from which an entire species is first described. This specimen will be referred back to by researchers, and other specimens are checked against it, time and time again. Happily for me, over the last few years it’s been my job to photograph this entire collection; this is one of my favourite specimens from it, and one of the moths which has stood out the most as I’ve worked my way through them all.

Many of the types in our collection are very old and inevitably some are a little the worse for wear. This particular female was collected from the Indonesian island, of Aru in 1857 by the famous naturalist Alfred Russell Wallace, and despite the fact that it’s over 150 years old it’s in extremely good condition – still a really impressive sight.

What’s on the van? – Granite

This week’s What’s on the van? comes from Dr Dave Waters, Curator of Mineralogical Collections and Monica Price, Head of Earth Collections.

The rock that goes home for holidays
Every year, a group of Oxford undergraduates travel to north-west Scotland to unravel the fascinating geological history of the area by studying the local rocks and how they relate to each other. They stop at various places to explore the geology, including the ‘multicoloured  rock stop’, an exposure of rocks in a road-cut north of Loch Laxford. This is where our sample of granite was collected in 1998.

It is very old, part of a suite of ancient Precambrian rocks known as the ’Lewisian complex’, named after the Hebridean island of Lewis. It formed about 1.7 billion years ago when magma – hot molten rock – was intruded into an even older metamorphic rock called a gneiss. The magma cooled down, forming crystals of different minerals: pink potassium feldspar, white sodium feldspar, transparent grey quartz, and black grains of biotite mica and magnetite.

The students learn to identify the minerals by studying thin sections of the rock, just 0.03mm thick, under a petrological microscope. This allows them to examine the distinctive optical properties of each mineral under polarised light. The Oxford Earth Sciences Image Store shows you what they can see.

Each year, this piece of granite travels ‘home ‘ with the students on their fieldtrip, and helps to teach them about the different kinds of rock they will see in the field. It is part of the large collections of rocks, fossils and minerals in the University’s Earth Sciences Department and the Museum of Natural History that are available for students to study.