考古抛出各种理论，都是猜测，没有确切的答案。
Radiometric Dating 同位素年代测定
- Radioactive Decay/ Nuclear Decay 衰变
- Half-life 半衰期
- stumble
衰变，是某些原子核自发射出某种例子儿边为另一种核的过程。
半衰期（英语：Half-life）是指某种特定物质的浓度经过某种反应降低到剩下初始时一半所消耗的时间。在物理学上，一个放射性同位素的半衰期是指一个样本内，其放射性原子衰变至原来数量的一半所需的时间。
Radiometric dating calculates an age in years for geologic materials by measuring the presence of a short-life radioactive element, e.g., carbon-14, or a long-life radioactive element plus its decay product, e.g., potassium-14/argon-40.
放射测年法，又称放射性年代测定法，是利用测定被测定物中某些放射性同位素与其衰变产物的比率，之后应用这种放射性同位素半衰期计算年代的方法，亦被称为绝对测年法
生物存活的时候，C12/C14的比率是一定的，因为不断与外界进行物质交换。但当生物死亡以后，这个比率开始发生变化，比率有一个衰退的时间周期，通过测定这个比率，可以根据对照表，推断出其生活的年代。
Relative Dating & Absolute Dating
C14 dating is Absolute dating.
Archaeologists have two main ways to tell the age of sites and artifacts. Relative dating tells how old something is in relation to other objects, but cannot provide a year or specific date of use. In contrast, absolute dating provides a specific calendar year for the occupation of a site.
Relative dating methods estimate whether an object is younger or older than other things found at the site. Relative dating does not offer specific dates, it simply allows to determine if one artifact, fossil, or stratigraphic layer is older than another.
Absolute dating methods provide more specific origin dates and time ranges, such as an age range in years. How specific these dates can be will depend on what method is used.
Words
- excavate 发掘
- excavation sites 发掘地点
- paleolithic 旧石器时代（hunting-gathering, nomadic life）
- mesolithic 中石器时代
- neolithic 新石器时代(settlement, livestock, agriculture)
- lithosphere 岩石圈
- chronological 年代的
- remain 遗骸（剩下的东西）
- Pottery 陶器
- Ceramics 陶瓷的
- antique 古老的
- artifact 手工艺品
- peat 泥炭
- surmise 推测
- occurrence 出现
- made of: material，由…制造的
- dump 垃圾场,垃圾，倾销
- skeuomorphs 纺织品
- ceramics 陶瓷
- bronze cauldron 青铜大锅
Articles
Pottery
- Kinds of archaeological evidence that pottery provides
- Why does the professor list several reasons that pots were traded? To support her claim that pottery provides evidence of distribution
- According to the professor, what is one reason it is important to study the material from which pottery was made? It can help archaeologists establish where the pottery came from
- According to the professor, why is it difficult to gain information on the function of a pot? (Click on two answers.) 1.Not all pots found in the same location have the same function; 2. Pots are rarely found in the places in which they were used
- What is a skeuomorph? A copy of an object, but made from a different material
Pottery can provide such evidence:
- dates, styles
- evidence of trade and distribution
- evidence of function
Infra Imaging 红外成像(可以发现sites)
- mural 墙，壁画
Instead of taking regular photographs, the satellite cameras take pictures using infrared light, which is invisible to the human eye, but computers can then process these images so our eyes can see them.
除了常规的摄像，卫星照相机使用红外线拍摄照片，红外线对于人眼是不可见的，但是计算机可以加工这种照片，使其对于我们可见。
Using infrared imaging, the satellite-based remote sensing instruments revealed what turned out to be traces of water storage systems and canals, canals that the Mayans built to irrigate their parched soil, which helps explain how the Mayans could feed such a large population.
使用红外成像，基于卫星的遥感仪器发现了最终被发现是储水仓库系统和水道，这些水道是玛雅人建造来浇灌他们干涸的土地的，这就解释了玛雅人是如何养活如此巨大的人口的。
The infrared images also revealed ancient roadways that had tied Mayan cities together.
红外成像也发现了古老的道路，这些道路把玛雅城市连通起来。
So the greens of the jungle are shown mostly as blue and red, but notice also the spots of greenish yellow scattered here and there.
绿色的丛林显示是蓝色和红色的，但也会呈现为黄绿色的小点。
These indicate significant discoloration in the vegetation, at least as it appears to infrared cameras.
这显示出重要的植被的变色，至少是在红外成像下变色了。
And Saturno notices that some of that discolorations located in exactly the spot where he found the pyramid temple.
Saturno注意到，一些变色地点和他发现金字塔的地点恰好吻合。
So he figures, hey, maybe some of those other yellow spots are worth investigating.
所以他觉得，可能其他的变色地点也需要查一下。
Well, long story short, he checks out three different spots where the photo shows discoloration and finds an ancient Mayan site overgrown with vegetation at every single one.
长话短说，他查看了三个植被变色的地点，发现了三个地点之下的确有一处玛雅遗迹。
Further exploration shows a perfect correlation between yellow spots on the infrared image and Mayan ruins hidden in the jungle.
更深入的调查展示了红外照片上变黄色的地区和藏在地下的玛雅遗迹之间有很大的关联。
Student: So what caused those spots to look different?
学生：所以是什么导致植被变色的呢？
Professor: Well, Saturno believes the limestone and lime plasters that the Mayans used to build their structures…
教授：Saturno相信玛雅人用来建造建筑的石灰石和石灰石膏……
Over time, uh, this limestone decayed and seeped into the soil and changed the soil’s chemistry.
经过长久的时间，这种石灰石腐烂掉，渗进土壤，改变了土壤的化学成分。
Then calcium carbonate from the decaying lime plaster might have been taken out by the roots of the trees growing there, uh, up into their leaves, and made them give off infrared light much more brightly than the surrounding vegetation.
腐坏的石膏产生的碳酸钙可能会被树木的根吸收，运输到树叶上，让这些树木在红外照射下放出比周围的树木更加明亮的光。
And infrared sensing technology can detect this.
红外感知设备就可以检测到这种现象。