why do you think scientists use mass extinctions to separate one era from another

Answers

Answer 1

Answer:

Eons, Eras and Periods are the three basic units of classification.

Explanation:

Geological time is broken down into Eons (very long term units), Eras (medium term) and Periods (shorter) units. There is also a fourth unit called Epocs that are even shorter time periods, but used mostly by specialists.

The boundaries between various units was initially determined by breaks in the fossil record. For example, the end of the Palaeozoic was when trilobites died out. End of the Mesozoic when the dinosaurs died out and so on.

With the discovery of radiometric dating, these boundaries could be determined more precisely and finer subdivisions, like Epocs, were possible.

More recently, from about 1970 onwards, there was growing evidence that many/most of these boundaries coincided with mass extinction events that killed off huge amounts of species.

Geologist are thinking of adding a new Epoc called the "Anthropocene" to reflect a time when us humans have had such a profound impact on the planet (mostly for the bad!). But to do this, would require a clear boundary in the geological record so that future geologist could recognize it - one option under consideration would be the radioactive fallout layer that occurs around the world from above ground atomic bomb testing in the 50's and 60's. This layer will be around for 10's of thousands of years or longer.


Related Questions

What is the bond of flour?

Answers

Answer:

Flour is a covalent bond

Flour is a covalent bond.

PLZ HELP MEEE






SNSMSNSS

S
S
S
S

S
S
S

Answers

WE HAVE MUCH TO LEARN FROM HISTORY. H

What theme tries to explain how and why places are similar?
Region
Location
Human-Environment Interaction
Movement

Answers

Answer:

Human-Environment Interaction

Explanation:

Human environment interaction is the way people adapt and modify the environment. ... The way people depend on the environment for food, water, timber, natural gas etc. The way people adpat the environment to fulfill their own needs.

Which country is in the top ten largest countries in the world? Peru Uruguay Argentina Venezuela

Answers

Answer:

Argentina

Explanation:

Peru is rather small

Argentina is the 8th largest country

Who accepted illegal bribes from the land companies that resulted in the Yazoo land fraud?

Answers

Answer:

a group of Georgia state legislators

Explanation:

According to socialists, what are some disadvantages of capitalism and free markets?

Answers

Answer:

FREE MARKETS

Poor Quality.

CAPITALISM

Monopoly Behavior or Waste Of talent or Uneven distribution of wealth

MARKING AS BRAINLIEST!! ( VALLEY FORGE, one reason why you would quit the army ?

Answers

The harsh environment that Valley Forge provided, This shows how difficult it was to survive at Valley Forge.


mark me brainiest if helped :)


What continent is the US a part of?

Answers

Answer:

North America

Explanation:

5.
Several large movie theaters decide to lower the price of movie tickets. How will this likely affect the demand curve for movie theater popcorn?



a. No shift

b. Shift right

c. Shift left

d. Not enough information

FOR ECONOMICS

Answers

If the price of the tickets are lowered the effect that it would have on the demand curve for the movie theater popcorn is that it would shift to the right. The right answer is b.

In economics if the demand curve shifts to the right it signifies that there is an increase in the demand for the popcorn.

In relation to the question, a fall in price always causes a rise in the demand of a product. Popcorn here is a complimentary good because people buy the tickets to watch movies and buy popcorn alongside.

If the prices of the tickets fall, more people would want to visit the cinemas, when this happens, it means that more people would have need for the popcorn.

This would cause the demand to rise and the curve shifts to the right.

Read more on https://brainly.com/question/15311353?referrer=searchResults

This English colony was founded by the Virginia company in 1607

Answers

Answer:

I believe the answer is Jamestown, Virginia (Jamestown Colony)

Explanation:

English men wanted to start a settlement in North America. Thus, after searching for some time, they settled with Jamestown, Virginia on May 13. This land was named after their King, James I.

3. In 2006, the Secretary of State added additional groups to automatically qualify as refugee-status.
Which countries/groups qualify?

Answers

Answer:

Afghans who do not meet the minimum time-in-service for a SIV but who work or worked as employees of contractors, locally-employed staff, interpreters/translators for the U.S. Government, United States Forces Afghanistan (USFOR-A), International Security Assistance Force (ISAF), or Resolute Support;

Afghans who work or worked for a U.S. government-funded program or project in Afghanistan supported through a U.S. government grant or cooperative agreement;

Afghans who are or were employed in Afghanistan by a U.S.-based media organization or non-governmental organization.

Explanation:

Hope this helps! :D

Action and reaction forces are described by which of Newton’s laws of motion?
options:
first, second,third,fourth

Answers

Action and reactions forces are described by Newton’s 3rd Law of Motion

The law states that, “Each action has an equal and opposite reaction”

In what trade circle was Quanzhou? What were their 5 tope exports

Answers

The city of Quanzhou was the eastern terminus of the historical sea trade route between China, the Middle East and Europe.

what aspects of urself do you think may be changed or would you like to change ?​

Answers

my everything hheheheheheh i’m serious

Which colonies had legal slavery?
A. Southern
B. All of them
C. New England
D. Middle

Answers

Answer:

I think it's B. all of them but I am sure it's the right one because every countries had it legal slavery.

I NEED HELP/ I’ll also give brainliest The terms representative democracy and republic are used when describing America’s government. Choose the THREE features of the type of government these terms are used to describe
A) The power of the government belongs to the citizens

B) People must have access to free and fair elections

C) Every citizen is required to Vote for representatives

D) Limits are placed on government and lawmakers

E) Every citizen gets a direct vote on every issue

Answers

The THREE features that describe the representative democracy and republic used when describing America’s government include "The power of the government belongs to the citizens."

Other features that describe the representative democracy and republic of American government include the following:

Every citizen is required to vote for representatives;Limits are placed on government and lawmakers.

Option A shows the definition of democracy that government power or authority belongs to the people.

Option C shows the definition of a representative government where people vote for representatives to make decisions on their behalf.

Option D shows the definition of the constitutional republic where the government and lawmakers' power are limited to the constitution content.

Hence, in this case, it is concluded that the correct answer is options A, C, and D.

Learn more here: https://brainly.com/question/25065854

this is my sis how does she look ​

Answers

Looks like a picture from g.o.o.g.l.e but either way that girl is still super pretty.

Many believe the U.S. constitution was made to be slow and time consumin. If this is true, why would the Founding Fathers have made the constitution this way?

Answers

Answer:

To allow each branch's actions to be checked by another branch

Explanation:

The founders were big fans of making sure any change of the constitution would be extremely difficult without near unanimous support

What’s ur favorite song?

Answers

Answer:

Any song by Straykids

Answer:

Girls by girl in red

Explanation:

Girls by girl in red

Why was the American Declaration of Independence used in other revolutions around the world?

Answers

Answer:

The American colonists were able to confirm an official alliance with the Government of France and obtain French assistance in the war against Great Britain.

Explanation:

...

People express feelings of love, sadness, anxiety and fear and this known as the ______________________ self. *

Answers

Answer:

inner

Explanation:

I believe it’s Inner self.

which is the most important level of law according to aquinas?

A: Divine
B: Eternal
C: Human
D: Natural

Answers

Answer:

C. Human

Explanation:

Thomas Aquinas, for example, identifies the rational nature of human beings as that which defines moral law: “the rule and measure of human acts is the reason, which is the first principle of human acts

2) How did Hitler and the Nazi party create hatred and disdain towards
the Jewish people beforeland during World War II?
A)
They distributed propaganda blaming the Jewish
people for the punishing terms created at the end of
World War I
B)
They put millions of Jewish shopkeepers and business
owners on trial for making a profit during religious
holidays.
They blamed Jewish politicians for the war crimes
committed during the invasions of Poland, Denmark,
and the Soviet Union.
They discovered proof that most of the people that
D) were boycotting German businesses were Jewish
politicians and activists.

Answers

Answer:

B

Explanation:

What did the Continual threat After war do from European
power and the Native Indians

Answers

Answer:

From the moment English colonists arrived in Jamestown, Virginia, in 1607, they shared an uneasy relationship with the Native Americans (or Indians) who had thrived on the land for thousands of years. At the time, millions of indigenous people were scattered across North America in hundreds of different tribes. Between 1622 and the late 19th century, a series of wars known as the American-Indian Wars took place between Indians and American settlers, mainly over land control.

Colonial Period Indian Wars

On March 22, 1622, Powhatan Indians attacked and killed colonists in eastern Virginia. Known as the Jamestown Massacre, the bloodbath gave the English government an excuse to justify their efforts to attack Indians and confiscate their land.

In 1636, the Pequot War over trade expansion broke out between Pequot Indians and English settlers of Massachusetts Bay and Connecticut. The colonists’ Indian allies joined them in battle and helped defeat the Pequot.

A series of battles took place from 1636 to 1659 between New Netherlands settlers in New York and several Indian tribes (Lenape, Susquehannocks, Algonquians, Esopus). Some battles were especially violent and gruesome, sending many settlers fleeing back to the Netherlands.

The Beaver Wars (1640-1701) happened between the French and their Indian allies (Algonquian, Huron) and the powerful Iroquois Confederacy. The fierce fighting started over territory and fur trade dominance around the Great Lakes and ended with the signing of the Great Peace Treaty.

King Philip’s War

King Philip’s War (1675-1676), also known as Metacom’s War, began after bands of Indians led by Wampanoag Chief Metacom (later called King Philip) grew frustrated with their dependence on the Puritans and attacked colonies and militia strongholds throughout Massachusetts and Rhode Island.

The attacks ignited a series of battles for power along the Connecticut River Valley between Metacom’s warriors and a large colonial militia and their Mohawk allies. The war ended with Metacom’s beheading and the near decimation of the Native Americans in his coalition.

Queen Anne's War

Queen Anne’s War (1702-1713) occurred between French and English colonists and their respective Indian allies on several fronts including Spanish Florida, New England, Newfoundland and Acadia. The war ended with the Treaty of Utrecht, but the Indians were not included in peace negotiations and lost much of their land.

During the Tuscarora War (1711-1715), uscarora Indians burned North Carolina settlements and randomly killed colonists over treaty disputes. After two years of bloody fighting, North Carolina defeated the Indians with the help of South Carolina’s militia.

In 1715, Yamasee Indians - frustrated with the loss of their hunting grounds and the high debts they owed white settlers of South Carolina - formed a confederacy with other local tribes and forced many settlers to flee, devastating South Carolina’s economy.

French and Indian War

As France expanded into the Ohio River Valley from 1754 to 1763, it fought with Britain for control of North America. Both sides forged alliances with Indians to help fight their battles. Known as the French and Indian War, the struggle ended with the signing of the Treaty of Paris in 1763.

In 1763, Pontiac Indians of the Ohio River became incensed upon learning King George III expected them to become British loyalists. During Pontiac's War, the Ottawa Chief Pontiac rallied support among other tribes and laid siege to Britain’s Fort Detroit. When a British retaliatory assault plan on Pontiac’s village was discovered, the Indians attacked and killed many British soldiers during the Battle of Bloody Run on July 31.

The Battle of Fallen Timbers happened on August 20, 1794, along Ohio’s Maumee River between regional Indians (Miami, Shawnee, Lenape) and the United States. The well-trained U.S. Army decisively defeated the Indians and the battle ended with the adoption of the Treaty of Greenville.

In 1759, a series of battles known as the Cherokee Wars began from the valleys of Virginia to North Carolina and southward. Two peace treaties forced the Cherokee to give up millions of acres of land to settlers, provoking them to fight for the British in the Revolutionary War, hoping to keep what land they had left.

Early American Indian Wars

Indians had to choose sides or try to stay neutral when the American Revolution broke out. Many tribes such as the Iroquois, Shawnee, Cherokee and Creek fought with British loyalists. Others, including the Potawatomi and the Delaware, sided with American patriots.

But no matter which side they fought on, Native Americans were negatively impacted. They were left out of peace talks and lost additional land. After the war, some Americans retaliated against those Indian tribes that had supported the British.

i added some other stuff in here just in case you need it

I need to help my daughter

Answers

Answer:

you know you dont have to lie and say for your daughter but antyways the answer is 2. Illinois 3. pennsylvania 4. Utah 5. Wisconsin

Mối quan hệ giữa văn học và chính trị

Answers

Answer:

ñeñeñeñeñeñeñ

Explanation:

ñacañacañca

how does democracy government powers

Answers

Answer:

Explanation:

how does democracy government powers\

Use the drop-down menus to identify the natural wonders described. This wonder best demonstrates the geographic concept of movement. This wonder receives very little rainfall and is a harsh environment for plants and animals. This wonder has the highest elevation and a highland climate. This wonder extends more than 1,200 miles underwater. This wonder is known as Africa’s “Garden of Eden” and is home to more than 20,000 animal species.

Answers

Answer:

This wonder best demonstrates the geographic concept of movement.  

✔ Serengeti Migration

This wonder receives very little rainfall and is a harsh environment for plants and animals.  

✔ Sahara Desert

This wonder has the highest elevation and a highland climate.  

✔ Mount Kilimanjaro

This wonder extends more than 1,200 miles underwater.  

✔ Red Sea Reef

This wonder is known as Africa’s “Garden of Eden” and is home to more than 20,000 animal species.  

✔ Ngorongoro Crater

Explanation:

Answer:

Serengeti Migration

Sahara Desert

Mount Kilimanjaro

Red Sea Reef

Ngorongoro Crater

Why was the Supreme Court’s ruling important in Gitlow v. New York with respect to due process?

because it used the equal protection law to interpret the issue of incorporation
because Gitlow's legal rights were used to interpret the issue of incorporation
because the Supreme Court believed Gitlow was guilty
because the Supreme Court believed Gitlow was innocent

Answers

Answer:

New York, 268 U.S. 652 (1925), was a landmark decision of the United States Supreme Court holding that the Fourteenth Amendment to the United States Constitution had extended the First Amendment's provisions protecting freedom of speech and freedom of the press to apply to the governments of U.S. states.

Explanation:

New York, 268 U.S. 652 (1925), was a landmark decision of the United States Supreme Court holding that the Fourteenth Amendment to the United States Constitution had extended the First Amendment's provisions protecting freedom of speech and freedom of the press to apply to the governments of U.S. states.

Answer:

B. because Gitlow's legal rights were used to interpret the issue of incorporation

Explanation:

see attached image

plzzzz help me
I'll mark u as brainliest​

Answers

Answer:

a = north direction

b= PO= post office

c = bridge

d = settlements or landscape

Explanation:

hope this helps

Other Questions
Which letter in the diagram represents the transition from liquid to gas? ABCD 2. Qu te __ (decir) el encargado ayer?Me dijo (decir) que yo ____(deber) volver maana why dont just give me my ticker hands in the car anything on you theres nothing on me thank you for helppp You save $35 a week for a year. How much do you have at theend of the year? (Hint: Use 52 weeksplease help a motor vehicle accident has resulted in a fracture where the articular surfaces of the tibial surface and femoral condyles are no longer in contact with one another. which term best describes this condition? the abnormal protrusion of a heart valve is known as 3Which finding would have disproved Virchow's hypothesis?O Animalcules are not organisms.O Animals are made of non-cell-based matter.Plants are made of non-cell-based matter.O Cells can generate from nonliving matter. How are the characters revealed in this excerpt from "The Cactus" by O. Henry? A. indirectly through character thoughts B. indirectly through character dialogue C. indirectly through character action What is meant by a phenotype ratio in a Punnett square?(1 point)the number of genes that are possible in offspringthe fraction of possible offspring that contain a certain allele in their genesthe fraction of possible offspring that can be observed to have a traitthe number of alleles in possible offspring what is the difference between indigenous and exotic trees Which option is a key point of cell theory?the answers are 1. Cells are the basic structural unit of all living organisms.2. Some cells can burn food molecules to release energy, but some cannot.3. Cells can repair neighboring cells, but not themselves.4. All cells that make up an organism are similar to each other.helppppppp I am doing a quiz Which of the following is a product of cellular respiration? Carbon dioxide Glucose Mitochondria Oxygen Research has shown that people who eat ______ get fiber, calcium, and other important nutrients needed for your body. It also tends to keep your weight under control and lower blood cholesterol levels.A. lunchB. snacksC. vitaminsD. breakfast in the story "The Old demon" Mrs. Wang was married at what age Which situation can be represented by the equation 4d + 5 = 29? what events happened in the Lottery (Paragraph please) answerrrrrrrrrrrrrrrrrr plzzzzzzz MARKING AS BRAINLIEST!! ( VALLEY FORGE, one reason why you would quit the army ? Why might a presidential candidate turn down public financing for the general election?