Househill Park in Nitshill exhibits a petrified tree stump reportedly extracted from a carboniferous sandstone unit quarried in the area. The location of the quarry is not known, however as the feature is reportedly locally derived, it is most probably from a sandstone bed in the Lower Limestone Formation or the lower part of the Limestone Coal Formation.
Parts of the upper root system and longitudinal surface grooves are still preserved. It is likely to be a sandstone cast of the trunk and upper root system of a Lepidodendron, similar to those seen at Fossil Grove in Victoria Park, but considerably more of the trunk is seen in this example. It is thought to be one of the largest examples of a fossil tree stump from carboniferous strata in the Midland Valley (the area lying between the Highland Boundary Fault and the Southern Upland Fault).
It has been reported that there were originally two trees in the park area but that one has been ‘lost’, possibly having been rolled into the river gorge adjacent to the site. Unfortunately graffiti is evident on the feature.
There is little information available regarding the tree and its history.
How tree fossils are formed
Fossilisation only happens in the rarest of cases, when the tree dies in the right circumstances. The wood usually rots away before fossilisation can occur. To become a fossil the tree needs to die in a location where it is protected from the elements. This means getting buried in sand, soil or mud. The best place for that is on the seabed or a river bed. There it is preserved due to a lack of oxygen which inhibits aerobic decomposition. As time passes, the tree becomes buried deeper and deeper. What was mud or sand becomes compressed on its way to becoming rock.
Safely sealed away underground, chemicals and minerals percolate through the sediment and the original tree gradually recrystallizes. In extreme cases, the entire tree can dissolve away, leaving a hollow where it once was. The minerals from the enclosing rock can gradually fill the hollow to create a natural cast of the original. So sometimes a fossil doesn't contain anything of the original tree except its shape.
In other cases, minerals from the rocks gradually impregnate the wood, changing its chemical composition and making it capable of surviving for as long as, or longer than, the rock enclosing it. Eventually the rock enclosing the fossil is eroded away, and the fossil is revealed on the surface of the ground.
In order to log this Earthcache you must email the CO answers to the following questions. ANY LOGS WITHOUT AN EMAIL BEING RECEIVED WILL BE DELETED WITHOUT NOTIFICATION.
1. Estimate the height of the fossil from the ground to the top.
2. Estimate the circumference of the middle of the trunk.
3. Give a brief definition of a ‘Petrified Tree’.
4. Describe the difference in the TEXTURE between the east and west sides of the trunk, eg. what can you see on the west side that you can’t on the east side? (The answer is NOT lichen or graffiti). Why do you think this is?
5. Please attach a photo to your log of you, your dog, gps, thumb or something personal to prove you were here. Please do not show any spoilers in your photo.
June 2019 the logging tasks for EC were updated. COs can now insist on a photo as proof of visit.
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Thanks to Glasgow City Council for permission.
WELL DONE TO THE SWEENEY TODDLERS ON I BELIEVE THEIR FIRST EVER EARTHCACHE FTF
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