Which best describes eras and periods?
Eras have a smaller time span than periods. Eras and periods are independent of each other. Eras and periods both appear at the start of the Cambrian period. Eras were more recently established on the time scale than periods.
What is the difference between eras and periods?
A period is a large interval of time with a definite characteristic while an era is a long period of time marking the start and end of an important event. 4.An era refers to a specific time period while a period may be used to refer to events that do not have any specific era or exact dates.
What method is most likely used to identify what happened before the start of the Paleozoic Era?
Which method is most likely used to identify what happened before the start of the Paleozoic era? Scientists examine fossil evidence during the Precambrian time. Which best describes eras and periods?
What is a gap in the geologic record called?
The surface where new rock layers meet a much older rock surface beneath them is called an unconformity. An unconformity is a gap in the geologic record. An unconformity shows where some rock layers have been lost because of erosion.
What are two ways rock layers can change?
What can change the way rocks appear? Gaps in the geologic record and folding can change the position in which rock layers appear. Motion along faults can also change how rock layers line up.
What are geologic gaps?
A gap is a geological formation that is a low point or opening between hills or mountains or in a ridge or mountain range. It may be called a col, notch, pass, saddle, water gap, or wind gap, and geomorphologically is most often carved by water erosion from a freshet, stream or a river.
What causes Unconformities to form?
Unconformities are a type of geologic contact—a boundary between rocks—caused by a period of erosion or a pause in sediment accumulation, followed by the deposition of sediments anew.
Where was Ash found India?
They discovered buried caches of Toba ash in the Narmada Valley in central India, at the Bori and Morgaon sites near Pune in western India, and in the southern Cuddapah basin in Andhra Pradesh, at a well-preserved site in the Jurrerru River Valley. They even found ash as far away as the Thar Desert.
Where was the ash found?
The ash plume from Iceland’s Eyjafjallajökull volcano, which crippled international air travel in April, held a shocking secret: an unexpected electric charge.
Why is Ash dangerous?
Inhalation of volcanic ash can be very detrimental to human health, due to the harmful aerosols and poisonous gases the ash is made up of. Health effects inlcude respiratory problems, eye problems, and skin irritiation. One long-term effect of volcanic ash is silicosis.