The tip of a new volcanic island appears above the surface of the ocean. Solidified black lava gleams in the sunshine. Although it may not be obvious, the processes that will turn this new piece of land into a tropical paradise have already begun. This video segment adapted from NOVA chronicles an island's transformation from a barren lava flow to a rich ecosystem.
How Did Life Emerge Here? (AD) (Video)
If you were to explore the ground in almost any terrestrial region on Earth, chances are you would find soil. This layer of Earth's surface is essential to life. It supplies, both directly and indirectly, what we eat and wear, as well as the oxygen we breathe. Even so, it's easy to take soil for granted. You might assume that the soil near your home or elsewhere has been there forever. However, the land surface has changed dramatically over geologic time. For instance, depending on its location, soil formation may have been interrupted by volcanic activity, glacial movement, or climate change. In some parts of the world, entirely new land masses are forming as you read this. So what is soil, how does it form, and how does it support life?
Soil formation begins with the weathering of rock through chemical and physical processes. When rock, such as that laid down by active volcanoes on the big island of Hawaiʻi, is newly formed, chemical and physical weathering begin almost the moment the lava cools. Rain, wind, and surf break large pieces of rock into smaller pieces, which are then broken into even smaller pieces. Soon, tiny organisms such as bacteria and fungi occupy small crevices in the rocks. Through respiration, photosynthesis, and chemosynthesis (the production of carbohydrates using chemical energy), these organisms produce gases and nutrients that support further soil development. As organisms die, they leave their remains behind. Each death contributes additional organic compounds to the soil. The nutrients, such as nitrogen and phosphorous, are stored in the soil, where other organisms use them. Eventually these organisms will contribute their own biomass to the accumulation of soil.
Environmental conditions affect the development of soil properties and characteristics. Climatic variables, especially temperature and precipitation, strongly influence the rate of the weathering of rocks and soil. The kind of soil that forms in a particular location also depends on the physical and chemical properties of the parent rock. Vegetation, as well as soil microorganisms, affects both the rate of soil formation and the composition of the soil. The topography, or the slope, shape, and direction of the land surface, affects how water travels through a landscape and determines the soil's resistance to erosion by water. Lastly, soil properties and characteristics are influenced by the length of time these processes have been in operation. So, when you see raw, unweathered, solidified lava, you are actually seeing the initiation of the soil-formation process.
Explore environmental factors involved in evolution of plant and animal life on Hawaiian volcanic islands in this NOVA classroom activity.
Academic standards correlations on Teachers' Domain use the Achievement Standards Network (ASN) database of state and national standards, provided to NSDL projects courtesy of JES & Co.
We assign reference terms to each statement within a standards document and to each media resource, and correlations are based upon matches of these terms for a given grade band. If a particular standards document of interest to you is not displayed yet, it most likely has not yet been processed by ASN or by Teachers' Domain. We will be adding social studies and arts correlations over the coming year, and also will be increasing the specificity of alignment.