What factors caused the Greeks to be known as reliable navigators

At any one time in the year at any one point on the globe, the sun and stars are found above the horizon at certain fixed heights at a distance that mariners can measure with as simple an instrument as one's fingers, laid horizontally atop one another and held at arm's length.

d) in the state of iowa

the colonial period, since this was a time of mass immigration from a variety of people from europe.