Active Topics Unanswered Topics. Why is radiometric dating not accurate for sedimentary rocks because they. xn--80aaamwkk0adpr.xn--p1ai → The London Artifact (Texas) - Bad Archaeology → Why is radiometric dating not accurate for sedimentary rocks because they. Pages: 2. You must login or signup to post new entries This column is made up of layers of sedimentary rock that supposedly formed over millions and even billions of years How Good are those Young-Earth Arguments: Additional Topics A great many dates, perhaps most, are rejects. That is, they were rejected because of internal indicators (such as a bad isochron) rather than on the basis of the final date produced. 13 Answer from Cobra 2018-12-15 09:45:08. Cobra.
Radioactive elements decay at a certain constant rate and this is the basis of radiometric dating. But, the decay elements need to be set, much like you would re-set a stop watch for a runner, to ensure an accurate measurement. When minerals get subducted into the Earth and come back as volcanic magmas or ash, this essential re-sets the radiometric clock back to zero and therefore a reliable age date is possible.
may have radioactive elements in them, but they have been re-worked from other rocks, so essentially, there radiometric clock has not been re-set back to zero. However, sedimentary rocks can be age dated if a volcanic ash horizon or a diabase sill or dyke can be found within the sequence. For example, if you find a dinosaur bone in a sedimentary sequence and you find an ash layer 10 meter above the bone and another ash layer 20 meters below it, you can determine the age of the two ash layers.
You can then infer that the dino must have lived some time between these two age dates.
best radiometric dating sedimentary rocks because they - Why is it difficult to date sedimentary rocks using radiometric dating techniques?
>> Sedimentary Rocks QUESTION: Can we date sedimentary rocks using radiometric dating techniques? ANSWER: Sedimentary rocks cannot be dated directly using radiometric dating, which is based on the idea that when rocks are in liquid form, their radiometric clock resets. This technique is generally used to date igneous and metamorphic rock, which are rocks that were once melted due to extreme heat and pressure.
Radiometric dating determines how long ago the liquid rock solidified into solid rock. Sedimentary rock on the other hand consists of sedimentary particles which were removed and deposited somewhere else by some sort of fluid (generally wind and water). The sedimentary particles predate the rock which they form.
Dating the particles which make up the rock wouldn’t give you the age of the rock itself. In addition, the redeposition process upsets the conditions necessary to achieve accurate results through radiometric dating.
Scientists believe they can indirectly date sedimentary rocks using radiometric dating if they find igneous or metamorphic rock imbedded in or around a sedimentary rock layer. This of course presupposes that radiometric dating works consistently as a dating technique in the first place. The assumptions which underlie radiometric dating are covered in our radiometric dating article published . WHAT DO YOU THINK? - We have all and deserve God's judgment.
, the Father, sent His only Son to satisfy that judgment for those who believe in Him. , the creator and eternal Son of God, who lived a sinless life, loves us so much that He for our sins, taking the punishment that we deserve, was , and according to the . If you truly believe and trust this in your heart, receiving Jesus alone as your , declaring, "," you will be saved from and spend eternity with God in heaven.
What is your response?
Sedimentary rocks are the second great rock class. Whereas are born hot, sedimentary rocks are born cool at the Earth's surface, mostly under water. They usually consist of layers or strata; hence they are also called stratified rocks. Depending on what they're made of, sedimentary rocks fall into one of three types.
• They're generally arranged in layers of sandy or clayey material (strata) like those you'll see in excavations or a hole dug in a . • They're usually the color of sediment, that is, light brown to light gray. • They may preserve signs of life and surface activity, like fossils, tracks, ripple marks and so on.
The most common set of sedimentary rocks consists of the granular materials that occur in sediment. Sediment mostly consists of — quartz and clays — that are made by the and of rocks.
These are carried away by water or the wind and laid down in a different place. Sediment may also include pieces of stones and shells and other objects, not just grains of pure minerals. Geologists use the word clasts to denote particles of all these kinds, and rocks made of clasts are called clastic rocks.
Look around you at where the world's clastic sediment goes: sand and mud are carried down rivers to the sea, mostly. Sand is made of , and mud is made of clay minerals. As these sediments are steadily buried over , they get packed together under pressure and low heat, not much more than 100 C.
In these conditions the sediment is : sand becomes and clay become shale. If gravel or pebbles are part of the sediment, the rock that forms is conglomerate. If the rock is broken and recemented together, it is called breccia.
Another type of sediment actually arises in the sea as microscopic organisms — plankton — build shells out of dissolved calcium carbonate or silica. Dead plankton steadily shower their dust-sized shells onto the seafloor, where they accumulate in thick layers.
That material turns to two more rock types, limestone (carbonate) and chert (silica). These are called organic sedimentary rocks, although they're not made of organic material as a . Although peat is forming in parts of the world today, the great beds of coal that we mine formed during past ages in enormous swamps.
There are no coal swamps around today because conditions do not favor them. The sea needs to be much higher. Most of the time, geologically speaking, the sea is hundreds of meters higher than today, and most of the continents are shallow seas. That's why we have sandstone, limestone, shale and coal over most of the central United States and elsewhere on the world's continents.
These same ancient shallow seas sometimes allowed large areas to become isolated and begin drying up. In that setting, as the seawater grows more concentrated, minerals begin to come out of solution (precipitate), starting with calcite, then gypsum, then halite. The resulting rocks are certain limestones, gypsum rock, and rock salt respectively.
These rocks, called the sequence, are also part of the sedimentary clan. All kinds of sedimentary rocks are subject to further changes during their stay underground.
Fluids may penetrate them and change their chemistry; low temperatures and moderate pressures may change some of the into other minerals. These processes, which are gentle and do not deform the rocks, are called as opposed to (although there is no well-defined boundary between the two). You can see that each type of sedimentary rock has a story behind it. The beauty of sedimentary rocks is that their strata are full of clues to what the past world was like. Those clues might be or sedimentary structures such as marks left by water currents, mud cracks or more subtle features seen under the microscope or in the lab.
From these clues we know that most sedimentary rocks are of marine origin, usually forming in shallow seas. But some sedimentary rocks formed on land: clastic rocks made on the bottoms of large freshwater lakes or as accumulations of desert sand, organic rocks in peat bogs or lake beds, and evaporites in playas. These are called continental or terrigenous (land-formed) sedimentary rocks.
How Do You Determine The Age Of Rock Layers?