What is the name assigned to a time break in the rock record?

What is the name of the simple hardness scale that runs from 1 to 10 and is based on comparisons with well known minerals such as quartz and talc?

What was the name of the supercontinent first proposed by Wegener?  

In science, a good theory is one that

A river with a very slight gradient, levees, and numerous oxbow lakes is in which stage of its lifecycle?

What type of plate boundary is associated with the formation of new crust.

Which of the following are mechanical weathering processes?   I. Frost wedging   II. Exfoliation   III. Carbonation

Which star in the following table would appear the brightest when viewed from Earth? Star Apparent magnitude mV Distance (parsecs) Absolute magnitude, MV Betelgeuse 0.58 153 −5.5 Deneb 1.24 433 −6.9 Rigel 0.12 265 −7.8 Vega 0.03 7.7 0.58

Which of the following factors influence the response of a rock to stress and strain?  I. the nature of the rock  II. the temperature of the rock  III. the pressure to which the rock is subjected  IV. the mass of the rock

Where do short-period comets (those with an orbital period of 200 years or less) originate?