McKeon Flats is formed by the Wosnesenski River, which flows into Neptune Bay on the south shore of Kachemak Bay on the Kenai Peninsula, about 14 miles (23 km) north-east of Seldovia and 9 miles (14.5 km) south-east of Homer, Alaska. The name first appeared on maps in the 1940s, published by the US Geological Survey and the US Coast and Geodetic Survey. It probably honors William J. McKeon, who was born in Pennsylvania to Irish parents, married Annie Nanitak in Seldovia and had a cabin on the flats in the early 1900s. The Wosnesenski River is named after the glacier that starts in the Kenai Mountains at an elevation of 4,800 feet (1,463 m) and flows generally west for six miles (10 km) to a proglacial lake at 500 feet (152 m). The river drains the lake and flows generally west-north-west for 12 miles (19 km) to Neptune Bay. McKeon Flats comprise deltaic sediments including Holocene glacial outwash and alluvial deposits from the Wosnesenski River, mostly consisting of gravel and sand eroded from the McHugh Complex graywacke that developed during the Cretaceous (about 143 million to 66 million years ago) and is exposed as bedrock on both sides of the river valley.

The Wosnesenski Glacier is named after Ilya G. Voznesensky, a Russian explorer. The glacier carved a U-shaped valley during the Last Glacial Maximum and has since retreated into the Kenai Mountains. The steep-walled valley was subsequently inundated by rising sea levels. The resulting embayment was shallow and eventually filled with sediment, creating McKeon Flats. Besides sea-level rise, Kachemak Bay and the west side of the southern Kenai Peninsula have experienced regional tectonic subsidence at least since the most recent deglaciation. Evidence includes the classic submergent morphology of drowned valleys and drowned shell middens. Parts of the coastline, such as McKeon Flats, are presently building fan deltas where the net rate of sedimentation exceeds the rate of submergence, though seaward portions of the deltas are periodically flooded because of regional subsidence. Nearly everywhere else in Kachemak Bay—with the notable exceptions of Fox River Flats and the Homer Spit—the coastline consists of sea cliffs cut by wave erosion in bedrock; sea stacks and sea caves attest to the dominance of wave erosion over deposition.

In 1839 the Imperial Academy of Sciences of St Petersburg sent Ilya Gavrilovich Voznesenskyi to Alaska to make scientific collections. He spent 1840-41 in California and from 1842 to 1849 was on Kodiak and in the Aleutian Islands and parts of western Alaska, where he explored and collected biological specimens and cultural artifacts. Voznesensky’s expedition lasted nine years and ten months. He brought back 434 mammals, 2,859 birds, 179 fish, five tortoises, 210 skeletons of mammals and birds, 1,052 ethnographic objects in 150 boxes, a herbarium on 2,000 sheets and a large geological-mineralogical collection. The expedition collected around 400 previously unknown species of plants and animals and established the world’s largest collection of ethnological artifacts of Russian America. Read more here and here. Explore more of McKeon Flats and Wosnesenski River here: