It's a "gold" shirt with an image of deeply degraded ancient garments removed from a bog in Denmark during an archaeological excavation in the 19th century. Shards of a wool tunic and some fragmented pants that have been semi-preserved in the peat for centuries, probably from the "viking" era. Why a shirt of old rotten clothes? To remember our future.
It also says Mount Eerie in white.
The garment was made totally in the USA out of 100% cotton by Bayside and masterfully printed in Anacortes by Paul of Granular.
(Image is pretty big on there. The shirt in the photo is a "large".)