Muncaster Creek near the British Columbia-Yukon border flows north into the Tatshenshini River. Gold was first discovered in 1927 and placer mining subsequently was carried out over 13 kilometres of the creek drainage. Records to 1945 indicate 92.3 kilograms (3251 ounces) of gold was recovered, although unrecorded production since then puts the total from the British Columbia section of the Creek alone at about 142 kilograms (5000 ounces). Most of the gold nuggets are very coarse, irregularly shaped admixtures of quartz, suggesting a local source. Rounded "well-travelled" gold nuggets are also reported, as well as pieces of native copper, native silver, magnetite, hematite, galena and pyrite. The underlying rocks are Permo-Carboniferous limestones, argillites, quartzite, schistose chloritic greenstones and amygdaloidal green- stones which strike northwest and dip steeply southwest. Abundant quartz veins are found in the creek bed in schistose rocks and in the surrounding area in sheared, altered diorite intrusions. The narrow veins striking parallel with the creek are locally strongly mineralized with fine disseminated pyrite. No gold has been found in these veins. Minimal glacial erosion in the area has resulted in thick overburden and few bedrock exposures. The depth to bedrock is up to 2.5 metres near the British Columbia-Yukon border (The "Dis- covery" claim) and increases both upstream and downstream into moranial outwash. Pleistocene till and stratified drift is overlain by reworked glacio-fluvial gravels. In a few places, gray boulder clay a few metres thick directly overlies bedrock. The glacial material forms remnant benches about a metre above the recent flood plain and channel. Placer mining in the British Columbia section was done mainly in the flood plain and channel, and in parts of the lower benches.