Exam 8: Geologic Time

Which two Paleozoic, geologic, time-scale periods used in the United States are combined into the Carboniferous period in Europe and elsewhere?

You are asked to interpret the geologic history of a county in Nova Scotia where the geology is quite complex.Aside from visiting various sites in the county for observing geologic sites firsthand, you are permitted to request five different pieces of information or data to aid in your interpretation.List the five that you would choose and explain why each is important for your study.

Which of the following denotes the divisions of the geologic time scale in correct order of decreasing lengths of time, beginning with the longest time interval and ending with the shortest?

The geologic time scale was devised before numeric dating using radioactivity was invented.

The Earth is billions of years old and its surface and interior have changed repeatedly by the same processes still operating today.

The half-life of carbon-14 is about 5730 years.Assume that a sample of charcoal formed by burning wood that lived 25,000 years ago.How much of the original carbon-14 would remain today?

The Cambrian Period is named after the Cambrian Mountains in Wales.

Who made the first clear statement of the law of superposition? When?

The term Paleozoic describes the era of ancient life forms.

What geologic law/principle states that fossil organisms (fauna)changed and evolved in a definite, progressive way such that strata of specific ages can be recognized by the fossils they contain?

In radiometric dating, an unstable radioactive isotope is called ________.

Working on fossiliferous strata in the mountains of western Italy, ________ was first to work out ________, which is the fundamental way geologists know which bed is older in any sedimentary sequence.

The ratio of radioactive parent to stable daughter atoms in a mineral is measured as 1:3.How many half-lives have elapsed since the mineral grain formed, assuming that only parent atoms were present when it crystallized?

a)In the chart of radioactive decay shown below, how many half-lives have elapsed by time? ________ b)How many half-lives have elapsed by time? ________

An unconformity is a buried ________.

A disconformity is an erosional unconformity with parallel beds or strata above and below.

James Hutton was the very first geologist to recognize the vast amount of missing time (at least all of Silurian)represented by the angular unconformity where the gently dipping Devonian "Old Red Sandstone" overlies vertical Ordovician slates at Siccar Point, Scotland.

What is the Jurassic Period named after?

Which organisms were free swimmers and found in a great variety of Paleozoic and Mesozoic marine habitats?

The Proterozoic Era is the first and oldest division of the Phanerozoic Eon.