The earth is probably more than 10,000 years old.

There are many independent ways of determining the age of the earth. The methods use different laws of nature, so they serve to cross check the estimates.1. Radiometric datingThe decay of radioactive materials provides accurate dating of rocks. For example, when potassium undergoes radioactive decay gaseous argon is produced. Melting a rock containing causes the argon to excape. Measuring the ratio of potassium to argon in a rock therefore indicates the rocks age. [2. http://en.wikipedia.org...] Actually, two isotopes of argon are produced. The ratio of argon39 to argon40 in the rock gives the age of the rock without having to separately measure the amount of potassium. [3. http://en.wikipedia.org...] Potassium-argon dating establishes the extinction of the dinosaurs as happening 66 million years ago.About twenty independent isotopes pairs having different half-lives support a common time line. [4. http://hyperphysics.phy-astr.gsu.edu...] Uranium 235 has a half life of 704,000 years, which makes it useful for very old rock specimens. The oldest rocks found on earth are [5 http://geomaps.wr.usgs.gov...] about 4.1 billion years old. The best estimate of the age of the earth 4.54 billion years. A natural nuclear reactor in Africa has been used to establish that radioactive decay rates for uranium and its products. have been constant for billions of years. [6 http://en.wikipedia.org...] Some lighter materials have small variations in decay rates depending upon environment, but worst case is about 4%, and those light isotopes are never used for radiometric dating. To allow for a young earth, something did affect decay rates it would have to speed up some isotopes by a factor of a million, on down to others by a factor of ten, and each in such a way that the dates each produced still agreed with each other. There are some theories that decay rates might be changing with the expansion of the universe, by an amount too small to detect. If so, that wouldn’t provide the large factors needed, and it would be the same for all isotopes, not the widely differing factors needed. Radiometric dating methods can occasionally produce large errors, for example if carbon specimens are not isolated from the environment or rock crystals have fractures. This is no different in principle from the occasional large errors that occur when rulers are used to measure length or a clock to measure time. Scientists send multiple samples to different labs to ensure accuracy. 2. Sandstone and the Grand Canyon Grains of sand begin as quartz crystals that form when molten granite hardens. Granite weathers by at the rate of one inch every 100,000 years, so it takes about hundreds of million years to produce a substantial amount of sand. There is no way to transport the very large quantities of sand required for the sandstone forming the Grand Canyon in less than millions of years. Sand only moves when there is active rushing water, not deep under water. The grains must be fused into sandstone in millions of years under high pressure. The sandstone formation of the Canyon took over 700 million years. [7. http://en.wikipedia.org...] If a few days of rushing water could carve the Grand Canyon, we should see new canyons forming all the time. Erosion is really a million times slower than that. The Grand Canyon required about 5.5 million years of erosion, during which time the land rose as the canyon was eroded. The sequence is volcanoes > granite > sand > sandstone > upheaval > erosion > Grand Canyon. That cannot all happen in 10,000 years. Creationists sometime claim Noah's flood is responsible for eroding the Grand Canyon, but there is only enough water on earth to account for a flood 200 feet higher than current sea level. [8 http://science.howstuffworks.com...] Moreover, there is no process by which 40 days of water could do anything measurable to granite, or even sandstone. One could blast a fire hose on granite for 40 days and nothing would happen beyond it getting wet. Granite weathers mainly due chemical attack from the atmosphere on the non-quartz components, a very slow process. 3. Sediment layers (varves) Sedimentation forms in layers in which less-dense and more dense materials alternate. If you shake up some material in water, the light stuff goes to the top. That’s not what we see in sediment layers. The layers include very light materials like pollen and, in estuaries, fish scales in layers with heavier materials. The types of pollen and fish scales in a particular layer indicate both the season and the climate when the layer was formed, providing a climate record back more than 30,000 years. A flood would not disperse spring pollen in separate layers from winter pollens, repeating over many thousands of layers. In more than twenty places around the world, sediments have accumulated in lake beds in continuous layers for more that 20,000 years. Because the varves contain organic material, the high accuracy of the number of layers is used to check radiometric carbon dating. For example: Lucke et al. (2003) describe a composite varve-dated 11.4-m-long sediment sequence from Lake Holzmaar in the Eifel region of western Germany, which extends back over 14 000 years, and from which a detailed carbon isotope record has been obtained (Figure 5.12). Variations in 613C values reflect changes in the lake ecosystem (dissolved CO2, nutrient availability, light, climate, water temperature, etc.) and constitute a proxy for environmental and climatic change. The mean time resolution for the isotope sequence is 14 years. [10. Mike Walker. Quaternary Dating Methods, p. 139] Lake Suigetsu in Japan has 29,100 varve layers. The older layers are difficult to distinguish, so the total accumulated error is 2000 years for the entire sequence. [11. Walker, op cit, p. 140] For dates at least to 14,000 years the layers are counted by computer and are extremely accurate. 4. Dendrochronology The oldest living trees are about 4700 years. The growth rings form a sort of bar code sequence. By matching the patterns in overlapping sequences from tree specimens preserved in bogs, the data shows trees were alive at least 14,300 years ago. “In central Europe, subfossil remains of oak and pine (Pinus sylvestris) found in the deposits of large rivers in southern and eastern Germany have been used to build a continuous Holocene oak chronology back to 10430 years, while a pine chronology, linked to this oak chronology, extends the dendrochronological record back to 11919 years (Spurk etal., 1998; Friedrich et al., 1999).” [12. Walker. op. cit, p. 127 “Dendrochronological demand the assignment of a single calendar year to a single ring. Various techniques are used to CROSSDATE wood samples to assure accurate dating.” The technique involves “matching ring-growth characteristics across many samples from a homogeneous area (area of similar environmental conditions).” [13. http://ltrr.arizona.edu...] In other words, scientists are not satisfied with the pattern of rings from a single tree, but demand that the pattern be correlated among many trees. Sometimes there are two growth rings in a single year due to a midsummer drought. Double rings are rare and are easily detected by their appearance. [14. http://www.talkorigins.org...] The real problem is that rings may be missing due to cracks in the wood specimen. Missing rings could make the dates appear erroneous young. The crossdate method ensures a precision to one year. The pattern of tree rings correlates well with the pattern in nearby varves, since both are products of local climate variations. Both dendrochonology and varves are confirmed by radiocarbon data. The data are conclusive: the earth is way more than 10,000 years old.