What makes Marlborough unusual as a wine region is the combination of long days, cold nights, bright sunlight and, in good years, somewhat dry autumns. With these relatively low temperatures the grapes could hardly ripen given the threat of autumn rains, whereas here they can generally be left on the vine and take advantage of a relatively long ripening period resulting in high sugar content without sacrificing, thanks to the cool nights, acidity. To the north of the area the soils are much newer than those to the south. In some places the water table is dangerously high, and the best vineyards, on these young, stony soils, are those where drainage is greatest, that is, on light, loamy soils above the gravel that once formed the riverbed.