Compared to the bedrock layers above and below the rock ledge shown at the waterfall, the characteristic that is primarily responsible for the existence of the rock ledge is its greater
1.
resistance to weathering
2.
abundance of fossils
3.
thickness
4.
age

The correct answer is option 1, that is, resistance to weathering.

Explanation:

After examining the picture of the waterfall, the feature, which is mainly accountable for the presence of the rock ledge is its greater resistance to weathering. Some kinds of rocks are very resistant to weathering. The igneous rocks, mainly the intrusive rocks like granite, weather gradually as it is tough for water to get inside them. The rocks behave distinctly to weathering because of the differences in the structure of mineral and its content.

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).