Answer:
volcanoes are formed by eruptions of lava and ash when magma rises through cracks or weak spots
The correct answer is - greenhouse gases.
The humans have been having a very big impact on the composition of the atmosphere in the past century, and that has started to result into changes in the climate patters all over the globe.
The main problem appears with the huge amounts of greenhouse gases released into the atmosphere, mostly carbon dioxide, but also methane. These two gases have properties that enable the greenhouse effect, which means that they are able to trap bigger amount of heat in the Earth's atmosphere, thus making it warmer.
If the ongoing trend continuous with the release of the greenhouse gases there will for sure be devastating effects on everyone and everything on the planet not so far in the future.
Answer:
I think c
Explanation:
Without access to medicines, Africans are susceptible to the three big killer diseases on the continent: malaria, tuberculosis and HIV/AIDS.
Approximately 97.5% of the earths water is salt water (saline), and 2.5% is fresh water hope this helps.
i. Using fossil evidences
ii. Similar rock lithologies at the edges of continent
iii. Climate clues
iv. Fitting of the continents into a puzzle
v. Sea floor spreading
Explanation:
Pangea was a super-continent on the earth which formed about 330 million years ago during the Paleozoic and began breaking up during the early Mesozoic, about 175 million years ago.
Most of the present day continents formed as a result of the separation of the Pangea in the early Mesozoic.
The first scientist to propose the existence of this super-continent was Alfred Wegener in 1912. He suggested the continental drift hypothesis to explain the separation of the land masses.
Today, the theory has been revised to the theory of plate tectonics which provides a better mechanism to understand the drifting of the continents.
Here are some of the evidences to support the existence of Pangea;
- Using fossil evidences: Mesosaurus, a reptile animal that lived during the Permian, was found in both South America and Southern Africa. Since this animal could not swim nor fly, only a jointed landmass could have made them present in both continents.
- Similar rock lithologies at the edges of continents: rock formations at the Western edge of Africa and South - Eastern part of Brazil matches with one another and have been believed to be once joined together.
- Climatic clues such as glacial tills that are confined to temperate and polar regions have been found in tropical regions.
- Wegener fitted the present day continent into a giant supercontinent and this provided a visual support for his claim.
- Evidences from sea floor spreading revealing magnetic reversals at divergent margins suggests the prevalence of plate tectonics i.e moving plates on earth.
This among many other evidences underscores the existence of a supercontinent called Pangea.
