| Pinguk River | |
| Name Etymology: | Iñupiaq language[1] |
| Nickname: | Pinauk |
| Pushpin Map: | Alaska |
| Pushpin Map Size: | 300 |
| Pushpin Map Caption: | Location of the mouth of the Pinguk River in Alaska |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | Alaska |
| Subdivision Type3: | Region |
| Subdivision Name3: | Northwestern Alaska |
| Source1: | Seward Peninsula of western Alaska |
| Source1 Location: | Brooks Mountain, Alaska, United States |
| Source1 Coordinates: | 65.8519°N -167.1564°W |
| Mouth: | Arctic Ocean |
| Mouth Location: | Arctic Ocean, Alaska, United States |
Pinguk River (alternate Iñupiaq language name, Pinauk meaning "hill")[2] is a waterway located on the Seward Peninsula in the U.S. state of Alaska. The river runs in a northwesterly direction for and then flows into the Arctic Lagoon about northeast of Cape Prince of Wales.[2]
The river flows over a length of in a zigzag course. Before the river joins the sea, at about upstream it forms two branches; the western branch is called the York River and the eastern branch is called the McKillop River.[3]
The York River rises on the eastern flanks of Brooks Mountain,[3] the highest point in the York Mountains,[4] in the central part of the Teller Quadrangle.[5] It flows in a northeast direction and then confluences with the McKillop River. The river flows through a valley formation of 200- width. The geological formation reported in the valley consists of slate and is exposed in some stretches of the river. The river bed is strewn with gravel and pebbles of slate and limestone. The gravel and pebbles have their origin in the Kuzitrin series. The limestones are derivatives of the Port Clarence limestones.[3]
The McKillop branch has its source in the limestone hills, which are an eastern arm of the York Mountains. The geological formation in this river valley is made up only of limestones and belongs to the Port Clarence formation.[3]
The York River, a branch of the Pinguk River, which rises in the Brooks Mountain, is reported to be rich in tin deposits in its head reaches in the mountains. The river bed is strewn with pebbles, boulders and granites, which is an indication that tin was embedded in granite contact zone in granite formations in the hills. However, no gold has been found in this river valley.[6]