How did the cataracts help ancient Egypt?
Nile's cataracts helped and hurt Egypt by flooding every year and bringing down boulders and trees. The Egyptians were protected from invaders due to their geographical features. Furthermore the cataracts in the Nile to the south protected the Egyptians from lands below them.
What is cataract of a river?
cataract, a waterfall (q.v.), especially one containing great volumes of water rushing over a precipice. Rhine Falls. Rhine Falls, on the upper Rhine River near Schaffhausen, Switzerland. Phter.
How did cataracts affect Egypt and Nubia?
How did the cataracts of the Nile affect Nubian trade? The cataracts prevented Nubians from trading by traveling on the river, so Nubian trade routes had to be over land.
What is the first cataract in Egypt?
The Nile River is shown above passing the granite islands that form the first cataract at Aswan City, Egypt. Cataracts occur where outcrops of granite, as well as other resistant rocks, reach the banks of the Nile River.
Why is a waterfall called a cataract?
The term “cataract” is derived from the Latin, “cataracta” which means “waterfall” and the Greek” katarhaktes” which means “waterfall, broken water; swooping, rushing down”.
What are cataracts caused by?
Most cataracts develop when aging or injury changes the tissue that makes up the eye's lens. Proteins and fibers in the lens begin to break down, causing vision to become hazy or cloudy. Some inherited genetic disorders that cause other health problems can increase your risk of cataracts.
What is the difference between a cataract and a waterfall?
A cataract is a type of waterfall with a large, single vertical drop, usually falling clear of the bedrock. A cascade waterfall is used to describe a waterfall running over an irregular steep surfaced gradient where the water is generally in contact with the river bedrock.
What does cataract mean in Latin?
"Cataract" is derived from the Latin cataracta, meaning "waterfall", and from the Ancient Greek καταρράκτης (katarrhaktēs), "down-rushing", from καταράσσω (katarassō) meaning "to dash down" (from kata-, "down"; arassein, "to strike, dash").
What is an example of a cataract?
A cataract is a clouding of the normally clear lens of the eye. For people who have cataracts, seeing through cloudy lenses is a bit like looking through a frosty or fogged-up window.
Why are my eyes yellow?
The whites of your eyes (called the sclera) turn yellow when you have a condition called jaundice. The whites of your eyes might turn yellow when your body has too much of a chemical called bilirubin, a yellow substance that forms when red blood cells break down. Normally, it's not a problem.
What does a cataract look like?
Clouded, Spotty, and Double Vision Like we previously stated, a cataract is characterized by cloudy eyes and vision. Because of the cloudiness cataracts cast over the lens of people's eyes, looking through an eye lens that is diseased with cataracts may seem like looking through a fog.
How did cataract Falls get its name?
An older expression for the same condition was web in the eye, so the name was most likely derived from the barred structure of the portcullis or window grating, rather than as a physical barrier. It sounds improbable, but nobody seems to have come up with a better explanation.
What is the best definition of cataract?
(KA-tuh-RAKT) A condition in which the lens of the eye becomes cloudy. Symptoms include blurred, cloudy, or double vision; sensitivity to light; and difficulty seeing at night. Without treatment, cataracts can cause blindness. There are many different types and causes of cataracts.
What do cataracts do?
A cataract scatters and blocks the light as it passes through the lens, preventing a sharply defined image from reaching your retina. As a result, your vision becomes blurred. Cataracts generally develop in both eyes, but not always at the same rate.
What is the rarest eye color?
green Of those four, green is the rarest. It shows up in about 9% of Americans but only 2% of the world's population. Hazel/amber is the next rarest of these. Blue is the second most common and brown tops the list with 45% of the U.S. population and possibly almost 80% worldwide.
Why do Africans have yellow eyes?
Higher Concentration of Melanin Most Africans have high levels of melanin that results in yellow eyes. Melanin determines the color of your skin, sclera and eyes. When this concentration increases, the eye color becomes light yellow or muddy brown.
What causes GREY ring around eyes?
Arcus senilis is when the cornea of your eye has a white or gray ring or arc around it. Your cornea is the transparent outer covering of your eye. It's also known as corneal arcus. It's common in older people, usually due to aging.
What is the difference between a waterfall and a cataract?
Horsetail: Descending water maintains some contact with bedrock. Cataract: A large, powerful waterfall. Multi-step: A series of waterfalls one after another of roughly the same size each with its own sunken plunge pool. Block: Water descends from a relatively wide stream or river.
Why is cataract called cataract?
The word cataract comes from the Latin word “cataracta” meaning waterfall, with the condition possibly therefore named after the white appearance of rapidly running water.
What is the meaning of cataract in Oxford dictionary?
noun. /ˈkætərækt/ /ˈkætərækt/ a medical condition that affects the lens of the eye so that you gradually lose your sight.
What is a cataract made of?
A cataract occurs when there is a buildup of proteins in the lens, creating protein clumps. These clumps, or deposits, prevent light from passing clearly through the lens, thus disrupting normal vision. There are several reasons why a cataract may form including: Aging – The eyes mainly consist of water and protein.
Do purple eyes exist?
Violet Eyes This color is most often found in people with albinism. It is said that you cannot truly have violet eyes without albinism. Mix a lack of pigment with the red from light reflecting off of blood vessels in the eyes, and you get this beautiful violet!
Can 2 blue eyed people have a brown eyed child?
This has to do with the fact that blue eyes are supposed to be recessive to brown eyes. This means that if a parent has a brown eye gene, then that parent will have brown eyes. Which makes it impossible for two blue-eyed parents to have a brown-eyed child — they don't have a brown eye gene to pass on!
Why are black people’s hair texture different?
African hair is generally characterized by tight curls and kinks, and grows almost parallel to the scalp. This hair type has the slowest growth rate, 0.9 centimeters per month, due to its spiral structure that causes it to curl upon itself during growth. An African hair strand has a flattened shape.
Why do African-American eyes turn blue?
Some possible ways an African-American person might have ended up with blue eyes are: Caucasian relatives in their ancestry (the most likely reason) A rare disease that causes albinism only in the eyes (ocular albinism) A new mutation that makes their eyes blue.
Are hazel eyes rarer than blue?
Hazel eyes are sometimes mistaken for green or brown eyes. They are not as rare as green eyes, but are rarer than blue eyes. Only about 5 percent of the population worldwide has the hazel eye genetic mutation.
Where do cataracts come from?
Most cataracts are caused by normal changes in your eyes as you get older. When you're young, the lens in your eye is clear. Around age 40, the proteins in the lens of your eye start to break down and clump together. This clump makes a cloudy area on your lens — or a cataract.
What is a cataract geography?
(ˈkætəˌrækt) n. 1. ( Physical Geography) a large waterfall or rapids.
Can eyes be GREY?
Gray eyes are very rare. Gray eyes are most common in Northern and Eastern Europe. Scientists think gray eyes have even less melanin than blue eyes. Gray eyes scatter light differently, which makes them pale.
Where do GREY eyes come from?
One theory is that dark gray eyes come from a thin layer of melanin on the front layer of the iris. The blue reflection of light is clouded over by the dark layer in front causing a dark gray color.