© Colin Frayn, Tree Ring Dating “Dendrochronology” –Trees (usually) grow one ring per year –Counting rings tells us a tree’s age –It can also tell us more… Climate affects a tree’s growth rate Different growth rates lead to different ring sizes So we can get a history of climate from tree rings Dating wooden artifacts –Of course, we don’t need to have a tree Wooden objects have tree rings in them We can line up those rings with calibrated tree rings Tells us when the tree was cut down to make the object

© Colin Frayn, Objections to Tree Rings Dendrochronology is used to date old objects (>10,000 years) –Wooden artifacts –Old (but long dead) trees Do trees reliably create 1 ring per year? –They sometimes create ‘double’ rings We can easily spot these and discount them The species commonly used for dating do this very rarely –Bristlecone pines: once in every few hundred trees –Ferguson, 1968, ‘Science’ vol 159 –They sometimes have ‘missing rings’ This would tend to make us underestimate the tree’s age Tree ring dating can be anchored –Wooden artifacts of known historicity –Evidence that correlates to known historical events E.g. unusually cold years after large volcanic eruptions Can calibrate tree rings very accurately

© Colin Frayn, Anchored Histories IntCal04 –The International Calibration for tree ring chronology –Agrees on a rigorous set of samples –Anchors dates back to 24,000 B.C. –Calibrated by Other tree rings Archaeology Carbon-14 dating Established scale Matched sample

© Colin Frayn, Oldest Trees in the World “Methuselah” (California, USA) –Estimated germination 2832 BC Germinated before the flood How did it survive the water? Clonal species –Original trees reproduce by exact cloning –Dalarna, Sweden Norway spruce Estimated age : 9,550 years –Mount Read, Tasmania Huon pine Estimated age : 10,000 years Oldest living tree is <5,000 years old –This doesn’t imply that the Earth is young! Img: Great Basin Bristlecone Pines

© Colin Frayn, Kei Mori and the Big Plants Japanese physicist ( ) –Grew tomato plants in special conditions –No UV, IR light –Highly pressurised CO 2 –Plants grew very quickly, provided high yield –Hypothesised that this might explain ‘giant’ biblical creatures I can’t find any research articles on this subject –How reliable is it? –The only reports I can find are creationist websites How plausible is the argument? –The vapour canopy idea is physically impossible See slides on the ‘flood’, ‘longevity’ –Dinosaurs were not just ‘overgrown lizards’ See slides on ‘dinosaurs & man’

© Colin Frayn, Genetically Modified Crops Hovind claims that GM crops are evil Norman Borlaug (b. 1914) –Credited with saving over a billion lives… –…by developing genetically modified crops No evidence whatsoever that GM is dangerous GM crops can reduce our need for –Fertiliser & Pesticides Vastly reduce the ecological damage caused by adding harmful chemicals to the environment Breed disease resistant, high-yield crops –Farmland Vast areas of rainforest are being destroyed to provide farmland for arable crops GM crops would reduce this