Falls Creek is located on the Kenai Peninsula, flowing generally south for 3.2 miles (5 km) to the northwestern shore of Kachemak Bay, approximately 17 miles (27 km) northeast of Homer and 2.5 miles (4 km) southwest of Kachemak Selo, Alaska. Named in 1904 by Ralph W. Stone of the US Geological Survey, the creek features a waterfall cascading 20 feet (6 m) over a coal seam near the beach. The lower portion of the creek lies within the Cottonwood Eastland Unit of Kachemak Bay State Park. The Border Ranges fault aligns roughly with the axis of Kachemak Bay. It juxtaposes Mesozoic sedimentary rocks of the Peninsular terrane to the west, underlying the Kenai lowlands, against highly deformed and metamorphosed Mesozoic rocks of the Chugach terrane to the east, forming the Kenai Mountains. The eroding bluffs on the northeastern shore of Kachemak Bay consist of fine-grained sedimentary rocks of the Kenai Group, a sequence formed during the Miocene, about 23 to 5 million years ago. Quaternary sediments cover most of the Kenai lowlands, and this rock formation is the only bedrock exposure along the Cook Inlet coast between the Kenai River and the Fox River. The Kenai Group comprises the Tyonek, Beluga, and Sterling rock formations. At Falls Creek, the bedrock is nearly continuously exposed in the precipitous wave-cut cliffs and steep stream canyon walls. It represents the uppermost strata of the Beluga Formation and the lowermost strata of the Sterling Formation. This sequence consists of at least 5,000 feet (1,500 m) of moderately to weakly hardened, locally conglomeratic sandstone with interbedded siltstone, claystone, and coal seams. The rock is highly friable, and active mass wasting has formed deep gullies. Talus cones have developed at the base of the sea cliff from accumulating rock fragments. The proportion of sandstone increases northward, and the number, thickness, and quality of coal beds decrease. The coal is relatively low-grade lignite to sub-bituminous, with beds generally lenticular and ranging from 3 to 7 feet (1 to 2 m) thick. Many former coal beds have burned, causing adjacent rocks to bake to a distinctive brick-orange color.

The archaeological record from Kachemak Bay reveals that maritime hunters of the late Ocean Bay tradition appeared briefly in the area around 4,500 years ago, likely arriving from the Alaska Peninsula. Approximately 4,000 years ago, a culture related to the Arctic Small Tool tradition emerged in the bay. By 3,000 years ago, the Kachemak tradition, closely linked to Kodiak Island, was established and persisted for about 1,500 years. This tradition can be divided into two phases. The Early Kachemak phase is evidenced by a midden on Yukon Island, where artifacts such as a primitive hand-thrown harpoon, barbed bone points, a simple stone lamp, fish hook barbs, and labrets were found. Animal bones suggest they hunted a variety of land and sea animals, including harbor seals, porpoises, marmots, and small whales. The Late Kachemak phase is identified through discoveries at Yukon Island, Cottonwood Creek, and Chugachik Island. Food preferences remained consistent, but weaponry advanced with multiple barbed arrowheads. This phase is characterized by exotic burial practices, decorated stone lamps, and semi-subterranean houses. At the Cottonwood Creek site, evidence showed that the people endured significant hardships. Many skeletons exhibited signs of degenerative bone diseases, arrested growth, and enamel hypoplasia, all attributed to malnutrition. The Kachemak tradition people abandoned the area about 1,500 years ago. Approximately 800 to 500 years ago, the ancestors of the Dena’ina migrated from the interior and adopted a maritime subsistence economy from the Alutiiq of the outer Kenai Peninsula. The Dena’ina established several villages in Kachemak Bay and many seasonal camps along the inner bay coast. A village called Soonroodna was known to early Russian explorers but has not been relocated. The Dena’ina also had a village on Yukon Island.

Coal was first discovered in Kachemak Bay at present-day Coal Cove near Nanwalek in 1786 by Nathaniel Portlock. In 1852, the Russian-American Company began mining it, continuing until the Alaska Purchase in 1867. The coal, supplied to Russian steamers, was of poor quality and sold at a loss. In 1888, the Alaska Coal Company started mining the Bradley seam at Fritz Creek. In 1891, Lieutenant R.P. Schwerin of the US Navy transported 200 tons (181 metric tons) of Kachemak Bay coal to San Francisco for testing. The results showed that the coal was of insufficient quality to justify the cost of extraction. In 1894, the North Pacific Mining and Transportation Company explored mining at Eastland Creek, constructing several buildings and a pier at the canyon’s mouth. A tramway was built from the pier to a tunnel in a coal seam about 0.5 miles (0.8 km) up the canyon. At least 650 tons (590 metric tons) of coal were extracted. Prospecting continued from 1894 to 1897 at Eastland and McNeil Canyons, but the only viable operation was about 3 miles (5 km) west of the Homer Spit. In 1904, the US Geological Survey explored Fall Creek and found numerous coal seams 1–2 feet (0.3–0.6 m) thick exposed in the bluff east of the canyon. A seam 2 feet (0.6 m) thick was near the base of the bluff and caused the waterfall. A seam 3 feet (0.9 m) thick was at an elevation of 90 feet (27 m), a seam 6 feet (1.8 m) thick at 170 feet (52 m), and a seam 4 feet (1.2 m) thick at 240 feet (73 m). All the coal was below commercial grade. In 1959, another US Geological Survey found that many coal seams at the head of Kachemak Bay had burned. This was indicated by thick zones of yellow to brick-red shale, baked to a flinty hardness. A few small burned zones were found along the escarpment west of Homer, and several extensive burned zones are exposed in the beach bluffs near Cottonwood Creek. Practically all the coal beds between Eastland and Swift Creeks have burned, with unburned coal only in ravine bottoms, kept wet by springs. Much of the burning is believed to have occurred recently. Read more here and here. Explore more of Falls Creek and Kachemak Bay here: