Mean sea level Select one: a. is a consistent value yet to be determined due to the variables involved in producing the tides. b. is at the same level along the entire North American coast. c. is based on average tidal levels recorded hourly at a given site over a period of many years. d. has very little variability across all ocean basins and, therefore, is treated as an absolute value. e. is constant enabling scientist to determine a single value thereof, though there are local minor variations.

The solstices and equinoxes, and the number of hours of daylight associated with each, are major factors in the seasons. use the drop-down menus to identify the month when each of these events occurs. the winter solstice in the northern hemisphere: an equinox in both hemispheres: the summer solstice in the northern hemisphere:

The impact of a large asteroid comet with earth has been proposed to have caused the extinction of the dinosaurs. the impact site of this comet is in or near

If you could drill a hole straight to the center of the earth, and keep track of what the hole is going through, youwould find: a) you would go through one sort of material, and then a different, denser material, and then a still-different, still-denser material, because the planet is made of concentric layers, sort of like an onion.b) you would go through one sort of material all the way to the center, because the planet is all mixed up.c) if your hole started at the north pole, you would go through different layers of different materials, but ifyour hole started at the equator, you would go through one sort of material all the way to the center.d) if your hole started at the equator, you would go through different layers of different materials, but if yourhole started at the north pole, you would go through one sort of material all the way to the center.e) you would strike diet pepsi when you got to the center.