Geology of Maui, HI6-9 March 2009

Our campground on Maui, Haleakalā National Park

It was rainy and cool (40s-50s °F) the entire time we were there!

Hawai’i is close to the equator and doesn’t really experience seasons. Knowing that we were camping on a volcano,how would you explain this weather?

This is an example of a volcanic fall deposit: it includes layers of volcanic debris that were projected into the air during explosive eruptions and fell to the ground.

But you can’t tell anything by looking at it this far away!

Geologists have to GET DIRTY to figure out how different formations came to be!

Debris about this size are called lapilli, which means “pea.”

This is a handful of the volcanic debris that formed the fall deposit…debris generally has to be pretty small to be carried by the wind before it falls to the ground.

Another reason we know it is a fall deposit is because the particles are rounded from flying through the air.

This is called a volcanic bomb: as you can see, it is much larger than most of the other debris in the fall deposit.

Anomalies (oddities) like this often appear in the natural world.

It is geologists’ job to come up with an explanation of rock

formations that accounts for most of

what they see.

Women geologists!

Laura

Kelsey

Jackie

One thing we see here is vegetation growing between the layers…this has to do with the porosity of the soil.

What is this top layer of soil called?

Another thing we see here is that the layers are no longer horizontal.

Why is there vegetation in-between some layers and not others?

What type of mass movement may have occurred here to shape the layers this way?

The island of Maui has two volcanoes.

This flat piece of land connecting the two Maui volcanoes is called the Isthmus…it formed from lava flowing off Haleakalā (the younger of the two volcanoes).

Island of Moloka’i in the distance

This picture shows the West Maui volcano, the older of the two.

Haleakalā CraterThe younger Maui volcano

3000 ft deep, 7.5 mi long, 2.5 mi wide, 22 mi circumferenceThe entire volcano is 33 mi long and more than 20 mi wide!

Because the West Maui volcano is the oldest, it has experienced more erosion.

What do you think caused erosion like this?

Akaka Falls State Parkon the “Big Island”

Streams like this form from water flowing down the volcano.

What force causes the water to flow downward?

Why are these rocks so much bigger…how’d they get here?

This is the‘Iao Needle.It is 2250 ft high.

Pretty awesome, huh?

How do you think it formed?

…a snail…

When a hot spot volcano, like those of the Hawai’ian islands, begins to die, its lasts “breaths” produce cinder cones (like these) along its flanks.

…or even like this!

Why would a cinder cone, which forms on the flanks of volcanoes, emerge from the water offshore?

Look at this awesome cliff! Do you see the debris in the water?

What type of mass movement do you think happened here to form this cliff?

Steep cliffs, like these, that form after landslides are called “pali.”

Landslides are a major threat to the Hawai’ian islands because they cause deadly tsunamis.

Photo taken on the “Big Island”

This deep cut through the West Maui Volcano is called an erosional valley.

Sugarcane is a cash crop in Hawai’i.It is grown all throughout the Isthmus.

What force acting on soil makes it smart for the Hawai’ians to grow sugarcane on the Isthmus, rather than on the flanks of the volcanoes?