Answer:
Photograph: bird's eye view of a site; interview: personal analysis and biased; tax records: limited accessibility; biography: unreliability of human memory.
Explanation:
There are generally always some drawbacks when considering different sources of historical information and a good researcher has to take these factors into account. Photographs are limited because they give you very little context. Interviews can be limiting because you get a personal view from just one individual. Tax records are likely protected due to privacy concerns and statutes. Biography can have drawbacks as well because the person may embellish past events or overemphasize the significance or attribute meaning in ways that are not entirely truthful or objective.
Answer:
potassium-argon dating
Explanation:
Potassium-argon (K-Ar) dating technique is the most appropriate dating method for establishing the age of a volcanic ash. It is most applicable for dating minerals and rocks more than 100,000 years old. It is based on measuring the product of the radioactive decay of an isotope of potassium (k) into argon (Ar). Since potassium is a common element found in many volcanic ash layer, the time since re-crystallization is calculated by measuring the ratio of the amount of argon 40 (Ar-40) accumulated to the amount of potassium 40 (K-40) remaining in these volcanic ashes.
Flammable gas, consisting largely of methane and other hydrocarbons, occurring naturally underground Advantages<span> & Disadvantages of </span>Natural Gas<span>. </span>Natural gas <span>burns cleaner than other fossil fuels, producing half the carbon dioxide as coal and about a third less than oil. It also emits fewer amounts of toxic chemicals like nitrogen oxides and sulfur dioxide.</span>
