7) Mean sea level 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 8) Rectangular drainage patterns form primarily as a result of A) differential resistance to erosion B) topographic uplift C) flow through anticlinal and unclinal topography D) flow through a faulted and jointed landscape E) hard resistant rock that prevents erosion