Expert: Ralph Salier - 1/22/2008

Question
QUESTION: Is it possible that ruins we uncover from ancient civilizations were made of more than just the stone we find?  Wood, after all, is organic and would eventually deteriorate to un unrecognizable form.  So, is it possible that some of the ruins we uncover incorporated wood or other building materials as well?  Is it possible that they are actually the foundations and frameworks of what once existed in the more pre-historic periods (i.e. the pyramids, ancient Incan ruins, etc.)?

ANSWER: Hi Brandon,

We think of ruins as stone structures. But you are right, we find many kinds of structures built of brick (fired), mud brick,  wattle and daub, sod, wood, skins and frames and simple wooden structures.  All of these leave behind very distinctive remains which can be identified. Some, like wattel and daub can be found in big chunks if the structure burned down since the fire would "fire" the clay and sticks into a pottery like consistentcy.

---------- FOLLOW-UP ----------

QUESTION: Sorry for the follow-up, but I'm so wrapped up in this train of thought that I don't know if I can sleep until my curiosity is satisfied!

Is it possible that some of the discoveries left by people alive prior to documented history look completely different from the images we see on TV?  For example, could the pyramids have been foundations for buildings that looked much different than a simple pyramid, but the other materials involved have been swallowed by the sands of the desert?  Also, when you say that other materials "leave behind very distinct remains", how long does that hold true?  Is it possible they would eventually disappear completely?  Thank you so much for entertaining my curiosity!

Answer
Hi Brandon,

I hope that you got some sleep.  Most reconstructions you see on TV are fairly good. As archaeology goes, we have existing buildings to look at and can compare techniques and methodologies of building.  Of course, physics plays a part too, you can only build so high using some materials before a structure becomes unstable. Mud brick is a great example.  To build over 2 stories with mud brick, you need a solid earth packed floor or foundation. Since most of these structures did not have this, a rain storm or earthquake would have knocked such a structure down.  They began to thatch the roof to protect the walls from the rain and this preserved the structures but mud brick is not strong enough for more then two stories.  When digging, the archaeologist finds "rings" or "squares" of very dense mud and clay showing where the location of such walls stood.  In later times, the mud brick was often capped by fired brick thus protecting the upper edges of the walls.  As fired brick became more popular, buildings began to grow in size and height since fired brick can support more weight. Some times stone foundations were used to help support the heavier walls.  Fired brick is a very stable material and survives in the archaeological record for thousands of years, just like pottery.  

When wooden structures are built or wattle and daub structures are built, post holes are often dug to set the upright beams to which the walls are attached. These post holes eventually fill in with rotted wood and other materials and can be seen in the soil as round features and when excavated clearly show that a log used to be in the hole.  Wood leaves behind remains which last for a very long time in the form of silica, that takes the shape of the wood's cellular structure, these are called phytoliths.  Many plants have these and you can identify the plant type from the phytolith. (Phyto - plant, Lith - stone).  

Can blowing sand erode structures, yes but it can also cover them up and protect them.  Even the type of soil, acidic or basic, can have an impact on the preservation of archaeological materials. but either way, ancient structures are preserved in some way.