Dino Tracks EarthCache

Dinosaurs in Israel? YES. About 200 tracks were discovered in the 60’s in Bait-Zayit. The site is open freely to the public, if the small gate is closed n call the community secretary (02-5346334, 8am-6 pm. also written on the gate) and she will gladly give the key.

דינוזאורים בישראל? כן. למעשה מעל 200 עקבות התגלו במהלך שנות ה60 במושב בית-זית. האתר פתוח חינם למבקרים אבל(!) השער לא תמיד פתוח וצריך לדבר עם המזכירות 02-5346334 בד"כ 8-16

What are fossil track?

When a person or an animal is walking (or moving) in soft sediment like sand or mud they are leaving an imprint in the ground they often leave an impression such as a foot print. This is very common in urban environment (walking your dog in a muddy path) BUT how can such tracks be preserved for millions of years?

It may come is not surprise that vast majority of tracks are not fossilized since they are destroyed shortly after they are made, again think about your dog leaving tracks and then it rains again destroying the tracks or even you walking after your dog erasing his tracks. So how do the tracks survive?There are several possible ways, the first is that another sediment such as soft sand will cover the tracks like a blanket, burying the fresh tracks and actually protect the footprints. Another option is when the footprint is made in a very soft sediment than the animal's foot (or human) sinks deeply into the sediment, creating a footprint below the surface, where it cannot be eroded. In both cases the buried tracks may later be re-exposed to the elements (wind, water) but they are now more tolerance. There characteristics changed for example the sediment had dried so it is not effected by wind or the print was filled with a different and harder sediment and it is less effected by the rain. The bottom line is that burial under the right conditions helps protect footprints.

But is burial alone ensure the long-term protection of the tracks? The short answer is NO. In order to ensure the survival of the tracks the sediment they are in (or made in) needs to become harder, undergo a process that is called lithification. This is a process in which sediments compact under pressure, the grains lose all the liquids that they poses (usually coordinate or van der waals bonds) the grains are then becoming more compact (shorter distance), and gradually become solid rock. When this happens the footprint that were imbedded in the sediment become fossilized just like the footprints you see in front of you in this earthcache.

So why dont we encounter more of these prints? After all Dinosaurs used to rule the earth?

The answer is simple, in order for these footprint to be preserve we need special conditions. First we need soft sediments that poses some amount of water (that can later be removed) to make the foot prints so it needs to be next to a water body, which also means there is a high chance they were destroyed shortly after by the same water body. There are some foot prints in sand dunes that were moistened by light rain or dew however they are rarer. But even if the footprints were made and fossilized they are still hidden. In order to see the prints we need to expose them, naturally by erosion or weathering or by human excavation.

Types of tracks

As hinted before we have different types of tracks we can have the original foot print (true track) of the animal or an evidence implying there was a mark. We can divide the possible outcome into four different categories:

A. True Track – The original impression made by the animal

B. Undertrack – We can affect the layers UNDER the foot print and that can undergo lithification. In this case we will have less details of the print.

C. Natural Cast- Sediment that fills the original print and they become harder and we preserve the cast of the original print. The cast preserve all the details of the original print.

D. Track Infills- Sometimes depressions in the layer of sediments deposited above tracks can also be filled. Like undertracks, track infills have less morphological detail. Track infills are very valuable since However they can be used to find fossil footprints which have not been completely exposed by erosion and reveal the true track.

In order to log this cache answer the following questions:

1. Based on the foot prints you see, what type do you think they are?

2. Describe the footprints you see.

3. In the sign next to the prints (only in Hebrew) what was the date the foot prints were discovered? (The last date written on the sign)

4. 4. Not mandatory : add a picture of yourself or your GPS next to one of the big Dino