The immensely heavy and rough white formation slithers slowly along the earth. The mile-deep monstrous phenomenon rips through the land as though it were a titanic hand with razor sharp nails. It takes hundreds of years for the glacier to form the lower portion of what will later be known as the Hudson River. When a glacier moves, it erodes the land by carrying away conglomerates of rock. In many cases, major portions of mountainsides are removed, resulting in sharp, vertical escarpments.
Glaciers have dark, long bands that can be seen on the sides and top called moraines.
Ice melts from underneath the moraines, and long ridges and scratches are often left behind as the glacier moves. Unlike many other rivers in the United States, the Hudson, due to its glacial origin, has multiple striations and tall, vertical cliffs on the land bordering the river. The upper portion of the river was formed just as any normal river, flowing down from higher altitudes. During the last Ice Age, which ended around 10,000 years ago, the glacier brought unconsolidated rocks and gravel from the arctic regions. Later, water from the northern regions and water from the Atlantic Ocean hit the melting glacier and formed a great river.