Dig Deeper

Manna from Heaven?

Getting the hang of these small creatures, you begin to realise there is a lot more to them than many people think.
Where did they come from? When did they appear on earth? Yet they do not 'appear' on earth, but  an integral part of it.

I suspect many of us have not given this matter much thought. It is if soil has always been there. But it has not.  It was not there when we span off from the sun over 4 billion years ago. Some may think it arrived like some 'manna from heaven'.  But - like all living entities - it must have evolved. That means it started as something, but due to various forces of nature, changed into something different - what we now call soil.  Soils are much the same the world over - although differing every few yards, consisting of various minerals, particularly sand, clay loam and millions of organic components, including bacteria, fungi, plant debris, small fauna, meso fauna and larger creatures.

But how what why when and where did soil come from?


Here we are going to ask these questions in relation to  the small soil creatures. 
Where did they come from? 
When were they first around? 
What is the geological relation with plants?
How do they go back in time with plants? 
Suddenly there are so many questions..
There is a whole new world to explore and discover.

Lets start with
When did the Soil Evolve?.Asking this question throws up just about every part of the curriculum you can imagine, so is ideal for interdisciplinary projects.  (link to Scottish Curriculum)
We have to go back in geological time frames, to study the evolution of the world most valuable long term asset - its soil. Starting with the zoology of these soil creatures, mixing with the botany around them,  controlled by the chemical conditions, exerted by the physical forces, the story of how the soil evolved brings together all these forces. And the soil animals gave me the clue to how it all fits together..

When did 'Higher Plants evolve? 
 We knwo fersn and mosses and 'bryophytes' have been around a long time. They all tend to need a lot of moisture. But when did 'Highr plants appear. 'Higher' doesnt mean taller, although in this case, it coincides. 'Higher' measn' further up the evolutionary ladder. It just so happens we are talking about trees, which alsoi happen to be taller!

ACTIVITY 
1. Determine when you consider the soil EVOLVED. If it is a living entity it must have developed over a period of time into the consistency and consituency that it is today. It is remarkably similar all over the world, despite every inch being different from the next.
2. Another grouop determine when trees first appeared on the planet.
Discuss what time frames each of you came up with, and whether they are the same.

It seems to have been around for a long time. But not 'forever'. Can you remember it in a reproduction of any geologial ages?
Make your prediction - and see how it matches up to this..

Let's look into this a lot more.. with Birth of the Earth... 


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