Geology - Eva Varga

Soil is a complex mixture of minerals, water, air and organic matter that performs many critical functions. In the United States, more than 80 percent of the population lives in cities or suburbs. While the downtown areas of cities are covered with asphalt and concrete, there are still lawns, trees, gardens, and parks. Under all this city space, even under the concrete, is soil.

Soils Support Urban Life

Before we began using pipes, drains, pumps, and other infrastructure to manage stormwater, nature provided the “green infrastructure” to slow, filter, and move water to where it belonged. In forests and wetlands, water is still managed naturally. The foundation of this network is the soil. It is the drain, the pipe, the pump, and the water treatment plant all in one.

As urban areas have grown and we’ve continued to pave over our soils, demands on both natural and manmade stormwater management systems have increased. The last few decades have brought a shift from traditional “capture, convey, and treat” drainage systems. Instead, many cities are beginning to focus on more sustainable systems to manage storm water runoff.

Often referred to as “green infrastructure”, these sustainable systems include rain gardens, living roofs, and the growing trend to plant vegetation native to the region. These practices can delay the arrival of water that reaches the sewer system and thereby reduce flooding.

The biggest benefit green infrastructure, however, is the potential reduction of pollutants entering the storm water system. Pollutants like nutrients (from fertilizers), road salt, and bacteria, can negatively affect aquatic life and public health. Green infrastructure captures these pollutants, especially those that might run off at the beginning of a storm.In both of the cities I have called home in the past few years, a few public buildings have even converted their roof tops to green space. These green roofs not only help to reduce pollutants but provide habitat for pollinators and small birds. In addition, they can provide learning spaces to learn about native plants and sustainable agricultural practices (drip irrigation, etc).

Bring it Home

The Soil Science Society of America recommends that urban dwellers consider rain gardens for their yards and compost their appropriate food wastes. Help the soil serve you by making rain gardens, making and using compost, and making an urban garden. Here are several resources and lesson plans to get you started:

Do the Rot Thing – Download this free composting curriculum to bring the science of composting into your curriculum
Build a Two-Can Bioreactor or small-scall indoor composting unit, or on a smaller scale consider a …
Soda Bottle Bioreactor that will enable students to design and carry out individualized research projects, comparing variables such as reactor design, moisture content, and nutrient ratios of mixtures to be composted.
Soil Science – Learn about basic soil science, and then explore some unique characteristics of soils found in urban areas.
Exploration of Run-off and Infiltration – In this unit, students design and conduct experiments on runoff and infiltration, either outside or in the classroom
Nourishing the Planet – Download the free soil science curriculum to help students realize the challenges of feeding a growing world
Dig It! Secrets of Soil – Visit the Smithsonian exhibit’s website to access 10 online interactive learning modules

In January, the U.S. Department of Agriculture (USDA) began its celebration of the International Year of Soils to highlight the importance of healthy soils for food security, ecosystem functions, and resilient farms and ranches.

This post contains affiliate links. Please see my disclosure statement for more information.

Healthy soils are the foundation of agriculture. In the face of mounting challenges such as a growing global population, climate change, and extreme weather events, soil health is critical to our future. Healthy soil is essential as global demands rise for food, fuel, and fiber. Soils also play a crucial role in food security, hunger eradication, climate change adaptation, poverty reduction, and sustainable development.

“Soil conservation is important because if we do not produce food , we do not eat.”

Over the course of the year, the Soil Science Society of America (SSSA) and other partners, will impart the importance of soil via monthly themes. Along with resource specialists and educators around the world, I will share with you the lessons and activities that I use with my own children. It is my hope that you find inspiration and resources to integrate these soil science lessons into your homeschool curriculum.

To begin, I have created this post as a means of sharing with you the print and online resources that I will be using with my students. This page will be updated periodically as we progress in our studies.

Print Resources for All Ages

Did you ever consider that with no soil there would be no life? Know Soil, Know Life will introduce you to an amazing world—the world beneath your feet. Published by the American Society of Agronomy, it provides a solid foundation about the world of soils. It is perfect for anyone desiring to know more about soil ecology. High school or undergraduate students will find Know Soil, Know Life is an easily accessible resource, but this book is for all ages. Everyone interested in being more environmentally conscious—the urban dweller, the young naturalist, the home gardener—can learn about the diversity of soils and their importance in our environment.

“We speak a lot of the importance of sustainable food systems for healthy lives. Well, it starts with soils.” ~ José Graziano da Silva, FAO Director-General

Also published by the American Society of Agronomy, SOIL! Get the Inside Scoop, provides a strong introduction to soil science for elementary students. Excellent descriptions of soil composition, importance of soil in the environment, and types of soil. This 36-page, full-color book explores how soil is part of our life ~ the food we eat, the air we breathe, the water we drink, and even the houses in which we live. The clear photographs and clear graphics enhance the text. The voices of actual scientists discussing the importance of soil scientists speaking directly to students brings the message of soil conservation home.

“The multiple roles of soils often go unnoticed. Soils don’t have a voice, and few people speak out for them. They are our silent ally in food production.” ~ José Graziano da Silva, FAO Director-General

Another fabulous resources is Life in a Bucket of Soil (Dover Children’s Science Books) by Alvin and Virginia Silverstein. The text and illustrations combine to introduce middle school students to the world of soil. I selected this one as our unit study spine and will be using it as guide as we undertake numerous hands-on activities.

Though this is a revised edition of the original 1972 publication, it is an excellent resource for homeschool. I particularly love that the illustrations are simple enough that we can utilize them as guides for our own nature journal entries. I’ve learned over the years that kids sometimes need examples to help them with their own illustrations.

Online Resources & Lesson Plans

In February, the theme is Soils Support Urban Life. Join me as I share lesson plans and activities to explore how rain gardens, living roofs, and composting can improve soil ecology – Do Your Part with Rain Gardens & Composting.

The March theme is Soils Support Agriculture. In my post, I share ideas to integrate writing and a contest sponsored by the California Foundation for Agriculture in the Classroom.

In April, I will share lessons and activities to teach students how Soils Clean and Capture Water. In May, the theme is Soils Support Buildings & Infrastructure.

For further soil ecology resources consider some of my earlier posts:

Science Career Options: Hydrogeology – Consider a field trip to a hydrogeologist office near you
The Rock Cycle – Lesson plan and free printables to learn about the rock cycle
Geospheres & Our Earth Systems – Activities integrating geosciences, technology, and art for middle school
Soil Erosion Experiment – As a part of a unit study on Africa years ago, we explored how different soils effect erosion
Field, Forest, and Stream – A series of three posts describing the outdoor ecology experiences we engaged in with STEM Club last year
Getting to Know the Millipede – One of the many invertebrates that live in our soils

This past week, I have been sharing with you our discoveries while we were in the Galápagos in a series titled, The Islands of the Galápagos. The strange beauty and attraction of these volcanic upwellings wove their mystery around us just as they have others who have visited since the archipelago was first discovered in 1525 by the Bishop of Panama, Tomas de Berlanga.

Today, I would like to expand upon the geology and geography of the Galápagos archipelago and share with you some of the resources that aided in our understanding of these enchanted islands.

The Galápagos archipelago consists of 18 main islands, 3 smaller islands, and 107 rocks and islets. The islands are located at the Galapagos Triple Junction – a confluence of three tectonic plates, the Cocos Plate, the Nazca Plate (which is moving east/southeast), and the South American Plate. It is also atop the Galapagos hotspot, a place where the Earth’s crust is being melted from below by a mantle plume, creating volcanoes.

Geology of the Galápagos

Geology (from the Greek γῆ, gē, i.e. “earth” and -λoγία, -logia, i.e. “study of, discourse”) is a field of science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which they change.

Plate Tectonics

Using our North Star Geography program as our guide, we learned about plate tectonics prior to our departure. There are three types of boundaries between tectonic plates:

Divergent Boundaries – where two plates are moving away from each other
Convergent Boundaries – where two plates push up against one another
Transform Boundaries – where two plates move horizontally, slipping past each other in opposite directions

After reading the chapter, we created edible models of the boundary types in STEM Club (see my earlier post, Plate Tectonics, for lesson details). This was a great activity and the kids really enjoyed manipulating the earth’s plates (i.e. graham crackers).

North-Star-Geography — As a Brand Ambassador for Bright Ideas Press we have received a complimentary copy of North Star Geography in exchange for our honest insights about how this program is working in real life with our family.

Dynamic Plate Boundaries

The lithosphere is broken up into 15 major plates, which move with respect to one and other. Mid-oceans ridges, a type of divergent boundary, are located at the edges of plates moving away from one and other on the ocean floor. One such mid-ocean ridge, the Galápagos Spreading Center, is located just north of the archipelago.

Mid-ocean ridges are often offset by fracture zones or transform faults. A major transform fault is located just north of the islands.

galapagosspreadingcenter Subduction zones occur where plates collide. A major subduction zone is located where the Nazca and Cocos Plates are subducting beneath the South American and Carribean plates. Subduction zones are marked by deep trenches and overlying chains of volcanoes (the Andes, for example).

Mantle Plume

The Galápagos Islands are one of most active oceanic volcano areas in the world. Like many oceanic islands, the Galapagos are thought to be the product of a mantle plume – columns of hot rock that rise from deep within the Earth. These plumes rise because they are hotter and therefore less dense, than the surrounding rock.

As a lithospheric plate moves over a mantle plume, a chain of volcanoes is created. The volcanoes get older in the direction of plate motion. The Galápagos Islands are located on the Nazca Plate, which is moving east-southeast. Thus, the islands get older to the south-southeast and it has produced a chain of seamounts known as the Carnegie Ridge.

A second seamount chain, the Cocos Ridge, extends northeast from the Galápagos Spreading Center. Thus a chain of volcanos was produced on both the Cocos and Nazca plates.

Geography of the Galápagos

Geography (from Greek γεωγραφία, geographia, lit. “earth description”) is a field of science dedicated to the study of the lands, the features, the inhabitants, and the phenomena of the Earth.

Volcanoes

In our North Star Geography text, we also learned that there are a number of different kinds of volcanoes. We observed two distinct types of volcanoes in the Galapagos. In the west, on the islands of Isabela and Fernandina, large volcanoes with an “inverted soup-bowl” morphology and deep calderas occur. In the east, smaller shield volcanos with gentler slopes occur.

One of the activities suggested in the North Star Geography activity guide, is to make a topographical salt dough or cookie dough map. The Galápagos islands were the perfect “model” for this activity.

In addition to the salt dough map, the kids enjoyed creating an accordion-style picture dictionary as we were traveling. You can download this free printable, Geography Picture Dictionary, for your personal use. It is a great supplement for North Star Geography. Children can sketch the geography specific to a region (as we did) or use it in a more general sense.

Craters & Sink Holes

The twin craters of Los Gemelos (one of which is pictured above) are a highlight of the Santa Cruz highlands. Though a lesser know attraction, Los Gemelos, are actually sink holes, not volcanic craters, on the highest part of Santa Cruz. These depressions were formed by collapsing underground lava tunnels.

Upland Forests

This region also boasts of a beautiful Scalasia forest with trees covered by many epiphytes. In recent years, however, some plants have been introduced that are invading the Scalesia pedunculata forest rapidly. What was interesting here was that in addition to the Scalasia, cacti were also present (though more abundant in the lowlands).

In contrast to the dry coastal lowlands, the highlands are covered by mist in the garua (foggy) season and receive thus much more moisture and support a more luxuriant vegetation.

If you would like to further explore the Galápagos from the comfort of your home or if you are planning to visit yourself, my multidisciplinary unit study, Galápagos Across the Curriculum, provides ample opportunity for kids to explore the diversity and remarkable history of the islands through a variety of hands-on science activities and projects.

I love when we can learn subjects by using real life examples, like using maps to work on geography. Whenever we travel, our first go to resource is a simple map, it helps us to get our bearings and to visualize the larger picture of how everything is connected.

My children have developed map skills to help with our vacation planning and to successfully find their way around the place we are visiting. To give you some ideas for learning on vacation, here are a few ways we reinforced map skills during our recent trip to South America.

To help us learn more about the many wonderful sites we would be visiting, we first used Google Earth to see the geological features such as the Andes Mountains where the Nazca Plate is sub-ducting under the South American Plate. We also viewed the Galápagos Islands and viewed the hotspot where new islands are forming.

We discussed the geological processes that are shaping the islands and how the plants and animals that live there are specifically adapted to life in this harsh environment. I shared with them the definition for endemic species and we talked about the species we were most looking forward to seeing ourselves.

This post contains affiliate links.

usingmaps

To add some learning to your vacation, use your guide maps/road maps as a teaching tool. Show your kids how to use them and then encourage them to navigate while sightseeing. They’ll love it and won’t realize that they’re learning too!

A map is a visual representation of a place or of information about a place. The place could be small, like a room, or larger, like a house, neighborhood, city, state, country, planet, solar system, or galaxy. – North Star Geography, Lesson 1

As a Brand Ambassador for Bright Ideas Press we have received a complimentary copy of North Star Geography in exchange for our honest insights about how this program is working in real life with our family.

While sightseeing in the Galápagos, Cristina – our interpretive guide, pulled out a bandana map at each island we visited to point out each of the surrounding islands. In time, the kids were able to correctly identify each of the islands themselves not only by their profile but by their geographical orientation as well. They were so captivated by this experience that a bandana map was their top souvenir choice.

Now that we are home, the kids are looking forward to creating an interactive map with My Maps, one of many mapping tools provided by Google Maps. They have already begun to flag the photos they wish to embed and have begun to brainstorm their storyline.

Tips for building map skills:

Help your children find maps before you depart on vacation. Take some time to look over them prior to departure or while en route to get the “lay of the land” before you arrive.
Identify the map’s title, legend, compass rose, and scale.
Help your child identify two points on the map and ask them to determine the best path to travel between the locations.
Document your travels using a map. At the end of each day, highlight the route you traveled and mark the things you did and saw along the way. Consider using My Maps to create an interactive map that you can share with friends and family.

Bright Ideas Press has created a survey to see what kinds of geography products homeschool moms most want. They need their feedback no later than Wednesday, Nov. 26.

As a thank you, you will receive a freebie code for an audio workshop at the end of the survey. It’s called History and Geography Through Literature, a $5.00 value.

Gravel, sand, silt, and clay, collectively known as sediment, are produced by the mechanical and chemical breakdown of rocks. Once disaggregated from the original source rock, this material is then eroded and transported by either wind, water, or ice, often ending up at the deposits of rivers or lakes, or ultimately as sediment in the sea.

In STEM Club last week we had learned how to identify rocks and minerals. This week, we took it a step further and discussed how scientists use the characteristics of composition and texture to help hypothesize where a sand sample may have been collected.
sandsaroundworld

Background Information

Composition

The composition of sediment is largely dependent on the source material. For example, the sand around volcanic islands is often composed of volcanic rock fragments, volcanic glass (obsidian), and mineral (such as olivine) associated with volcanic rocks. Sediment found on beaches of southern California are largely composed of quartz and other minerals associated with igneous rocks, which form the bulk of our local mountain ranges.

In areas where there is no good source of sedimentary material from nearby mountains or volcanoes, the sand is often entirely composed of organic material (i.e. shell fragments, coral, etc). These sediments are called carbonates, because they are nearly entirely composed of calcium carbonate (CaCO3).

Texture

The texture of sediment is largely determined by the transportation process. The three important characteristics used to assess the texture of sediment are rounding, size, and sorting.

Rounding

As material is transported, it is subject to abrasion and impact with other particles which tends to “round-off” the sharp edges or corners. A well rounded sand grain has probably traveled a great distance from its original source area, while angular grain has probably only been transported locally. However, large particles tend to round much faster than smaller particles.

Grain Size

The terms gravel, sand, silt, and clay carry with them a size connotation. Gravel is any material greater than 2 millimeters in its largest dimension. This includes boulders, cobbles, pebbles, and granules (in decreasing size order). Sand is any material between 2 mm and 0.06 mm in size.

We usually sub-divide this category into very coarse, coarse, medium, fine, and very fine. In practical terms, very fine sand is about the smallest grain size you still see with your naked eye. Silt is material which is finer than sand, but still feels gritty when rubbed on your teeth. Clay is the finest material of all, and pure clay will feel smooth on your teeth, and will form a sticky ball when wet.

As a general rule, material gets smaller the more it has been transported. Therefore very coarse material usually indicates a short distance of transport and vice versa.
sorting

Sorting

The sorting of a sediment is simply how well the sedimentary material is separated out by size. For example, if all the grains in a sediment sample are very nearly the same size then we say the sample is “well- sorted”. If a sedimentary sample were to contain pieces gravel, as well as sand and silt, it would be a “poorly- sorted” sample.

Sorting is primarily effected by the agent of transport. Water is an excellent medium for sorting of particles by size and density. Wind is probably the best sorting mechanism of all, but of course, only operates on the finer grain sizes (not much gravel is moved by wind transport). Ice is the poorest sorting mechanism, transporting and depositing all sizes of sediment with equal ease.

Sand PowerPoint

Some time ago, I found a wonderful Sands PowerPoint but I have sadly been unable to locate it again. Please – if you are familiar with the original source, I would so much like to point my readers directly to the source and give proper credit.

The following image is a slide excerpted from the presentation. Three sand samples have been photographed under magnification from which the roundness of each sample can easily be identified. The graph below each sample illustrates how well the sedimentary material or sand sample was separated by size.

sands
Sample 1 – This is a medium sized sand with a few sea shell fragments. The sorting of the sand is good. There is not a huge variation in the size of the sand. The graph shows a bell curve with a relatively equal distribution of small, medium, and larger size grains. This is a good example of a BEACH SAND.

Sample 2 – This is a classic example of a DUNE SAND. It is very well sorted and fine grained. Well sorted means that the size of the grains is not varied. Most of the grains of this dune sample are in one size group (96.7% are in the size .009 to .005).

Sample 3 – This is a very poorly sorted sand. There are coarse particles and fine grained particles. This, along with the fact that the sand particles are very angular are the indications that it is a RIVER SAND. In other words, it has not traveled far from its original source.
sandslab

Hands-on Sand Lab Activity

Materials

At least 4 different sand samples collected from different locations; the greater the variety the better
Metric ruler
Microscope
Microscope slides
Sand gauge (optional)
Sediment or sand sieve kit (optional)

Procedure

In their science notebooks, I instructed the students to create a data table with the following 8 column headings:

Sample Name or Number and Location
Color
% Dark Minerals
Grain Size
Rounding
Sorting
Organic Material
Other (probable origin, sketches of grain shape, etc.)

I then encouraged them to examine at least 4 different sand samples from the sand collection provided. To guide their observations, students were asked to fill out the table as they went along. A microscope was also available so they could observe their samples under magnification.

Using the data on their charts and their microscope observations, students should have been able to identify the environment of deposition (beach, dune, or river) of the various sand samples.

It is not easy to tell the difference between rocks & minerals because there are so many kinds of them. It takes years of study to be able to accurately identify a mystery rock.

Last week, we learned of the rock cycle which describes the dynamic changes over time among the three main rock types: sedimentary, metamorphic, and igneous. Today, the kids took part in two rock identification labs to further develop their understanding of the basic rock types.

A mineral is a naturally-occurring substance formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock is a naturally occurring aggregate or combination of minerals. Rocks do not have a definite chemical composition. All rocks are made of 2 or more minerals, but minerals are not made of rocks.

The Three Main Rock Types

Twelve stations were set up around the room – each with a rock specimen and a card that provided hints as to how that rock was formed. The students rotated amongst the stations and recorded first the name of the rock and then identified which of the tree rock types to which it belonged.

Here are just a few examples of the text clues given on the cards:

Marble :: In the past this was a sedimentary rock called limestone. However, heat and pressure have changed it into a much harder rock called marble. Marble today is used as a building material.

Limestone :: This rock formed when the small skeletons of diatoms, plankton, and other water animals sink to the bottom and are then buried and squeezed to form rock.

Pumice :: This rock came from the foot of a small volcano in central Oregon called a pumice cone. It is so full of holes that it will float in water.

Identifying Rocks – Using a Dichotomous Key

We then utilized a dichotomous rock key to identify a dozen or so small rock and mineral samples. In most cases, we don’t see a rock during its formation, so we rely on rocks’ observable clues to infer their formations. Two clues that indicate a rock’s formation are its composition and texture.

Composition refers to what a rock is made of. The color of a rock can provide a clue to the composition. Fragments of other rocks, fossils, and identifiable mineral grains are also aspects of composition.
Texture is a description of the rock material. It includes characteristics such as crystal size and shape, number of different grain sizes, and alignment of grains.

Together we observed the rock’s texture, conducted a basic hardness test, and identified the minerals that compose it as best we could.

When Using a Rock Key there are a few things you need to know:

When minerals have the time and space to grow into their crystal forms, they grow to beautiful regular shapes that are easy to recognize once you have seen a few examples. In rocks, crystals grow up against each other; they have straight edges and often show flat shiny faces that reflect light like tiny mirrors.

Grains that are not crystals in rock do not have flat shiny faces. They are rounded, like grain of sand, or jagged, like a piece of broken rock. Grain size in rocks can mean the size of crystal grains or of fragments:

Coarse Grained – the rock is mostly made of grains as large as rice, or larger
Medium Grained – the individual grains can be seen without a magnifier, but most of the rock is made of grains smaller than rice
Fine Grained– the individual grains can not be seen without a magnifier

Layers in rocks show in different ways.

In some rocks (gneiss for example) different colored minerals are lined up in ribbons.
In schists, the layers are most often thin layers of mica or chlorite around masses of feldspar or quartz. The top and bottom is almost always mica or chlorite.
In sandstones, different sized sand grains sometimes show as different colors. When the grains are sorted by running water or wind, they show different shades of the same color.
The layers in slate are very thin and straight. The top and bottom layers are usually flat and quite smooth.

Gas bubbles form round or elongated holes in rocks. In pumice, the bubbles may be very tiny. In scoria or vesicular basalt, the bubbles are larger, often as large as peas.

rocktypes

For more information on rock types and identifying rocks, I recommend these resources:

The Rock Identification Key – An online, interactive dichotomous key that walks you through precise steps (no photos)
Identification of Minerals – This website provides clear definitions for common terms or characteristics used to id rocks (cleavage, luster, specific gravity, streak, fracture, etc.)
Rock Identification Tables – A website to help you identify rocks (the tables are clear and provide full color photographs of many rock samples)
Simon & Schuster’s Guide to Rocks & Minerals – An easy to use field guide that contains everything rock and mineral enthusiasts need to know, +1,000 spectacular illustrations
Smithsonian Rocks & Minerals Handbook – Another great field guide that combines 600 vivid photos with descriptions of more than 500 specimens.