Geology Postcards

Over the years, I have taken hundreds of photos to use in my Earth science teaching.    Here I am sharing them to those who have joined my email list so you can use them in your classroom.   I will add a new image to this page after it has been sent around by email.

Click on the images to get a higher resolution image to use in your teaching collection.

You can use the images for educational non-commercial use.   The images are not to be altered in any way without receiving permission.

Diamond DrillDiamond Core Drill

When we want to see what is happening to the geology underground we can use a number of drilling techniques to collect underground rock samples.  The best of these techniques is using a diamond core drill.

This process works by grinding the diamond drill bit (pictured) into the rocks.   The surface of the drill bit is encrusted with industrial grade diamonds which can cut through any type of rock.  What is left is a column of rock, called a core, that slides up into the drill tube.  This can then be collected and pulled up to the surface where geologists can examine the rocks, their textures and how that relate to each other.

Later geophysical devices can be lowered down the hole in the ground that this drill had made and further measurements of rock properties can be examined.


Mauna Kea

Mauna Kea – Hawaii’s tallest volcano

Standing 13,796 feet (4205m) above sea level, Mauna Kea is Hawaiian for the “White Mountain”.   A massive shield volcano Mauna Kea, which sits on the Big Island of Hawaii, can get a coating of snow in the northern hemisphere winter….and even has a ski club!

It last erupted in 2460 BC and is capped by numerous small cinder cones which are thought to represent a final capping stage of Hawaiian shield volcanoes.

The lower half of the image shows the dark greys of a basalt lava flow from Mauna Kea’s sister volcano, Mauna Loa, which is behind the photographer. These flows occurred in the 1980’s.


Tsunami MemorialTsunami Memorial

In the very early hours of April Fools Day in 1946 a large earthquake (Magnitude 7.4) in the Aleutians generated a tsunami that traveled across and around the Pacific Ocean basin.  It hit Lapahoehoe Point on the Big Island of Hawaii around 7am just as students and teachers were preparing for school.

Twenty-five people, including sixteen students and five teachers were killed at the location.   The remnants of the school and some of the teacher residents remain to this day.   This tsunami memorial, which stands just feet away from the Pacific Ocean, records the names and ages of its victims.

In total 159 people were killed in the Hawaiian islands by this tsunami disaster.   Just two years later the Hawaii Tsunami Warning System was put into place.


Mill BallsCrushing – Ball Mill Balls

When ore is mined it arrives at a processing mill as large rock chunks.  Those chunks need to be ground down to a fine powder so that the metals can be extracted.   One part of that process is to put the ore into a large rotating drum which contains large steel balls.  This device is called a Ball Mill.

The very act of grinding down ore into a powder also grinds these steel balls down to a smaller size.  The mill operator then has to extract the eroded balls and replace them with new balls and start the process over.  The old balls are then recycled.

The powdered ore leaves the ball mill and is further processes.  Froth flotation, gravity separation and other methods are used to remove the valuable metals and metal compounds from the waste minerals.

Kilauea Summit Plume

Volcanic Plume of Kilauea

A volcanic plume of gases and steam rises from a crater in the summit caldera of Kilauea volcano on the Big Island of Hawaii.  The sulfur dioxide in the plume (and other gases) reacts with the atmosphere to form a volcanic smog (called Vog) that blows away from the summit and around to the other side of the island.

Kilauea has been erupting continually since 1983, mostly centered on the east rift zone flank.  This summit eruption phase started in March 2008.

In the far distance you can see the long slope of Kilauea’s big sister volcano Mauna Loa – arguably one of the Earth’s largest volcanoes.

Lava GlowLava Glow

Kilauea volcano, on the Big Island of Hawaii,has been in an eruptive phase since 1983.   During most of those 30+ years, lava has been erupting from a vent on the eastern rift zone of the volcano and traveling down the volcanic flank and into the ocean creating new land and covering forest, field and homes.     In March 2008 another vent opened up deep in the summit caldera of the volcano within the pit called Halema’uma’u forming a lava lake.  As the lava bubbles up and circulates in the lava lake it releases gases (steam, sulfur dioxide etc) creating volcanically derived smog, known as Vog.  During the day the gas plume is about all visitors can experience of the eruption at the summit.
However at night that gas plume takes on the most majestic glow from the lava lake below.

The eruption also continues on the east rift zone, but for the last 18 months those lava flows has been moving away from the ocean and heading down the other side of the volcanoes flank towards the population center of Pahoa.

These flows, as well as the summit eruption, are monitored very closely by the USGS Hawaiian Volcanoes Observatory staff who provide advice to the island authorities such as Civil Defence.

Mapping a Lava Tube

Mapping a cave

You are probably familiar with modern mapping techniques that use Global Positioning Satellites (GPS) , satellite images using light and radar and combining layers of data using a Geographical Information System (GIS).  All these techniques rely on one important thing – they all need to be able to see the ‘sky’.  So what if you want to map inside a cave.

Mapping a cave or an underground mine requires the use of measurement techniques using compass bearings and accurate dimensions (height, length and width).  In the past tape measures were used to do this task – but now laser measuring devices are used.

Here a group of students is measuring the dimensions inside a lava tube – a cave formed by a lava flow which emptied when the eruption stopped – to work out the volume of lava that once flowed through the tube.   They use the laser ‘tape’ measure to take dimensions around the diameter of the tube, then calculate the average diameter of the tube.  They do the same at set intervals along the tube, then average out the dimensions and work out a volume.

You could do the same in a hallway in your school (and have students imagine they are in a cave.