The Palmer gneiss
INTRODUCTION The Palmer gneiss was originally described as a part of the Basement Complex of the Marquette district in northern Michigan. 1 This gneiss was thought to consist of Archean rocks intruded by Laurentian granite. More detailed work later disclosed that some of the rocks designated Palmer gneiss are Middle Huronian sediments. 2 Also, since these Huronian sediments were found to be extensively intruded by granite, it became evident that this granite must be as late as Middle Huronian and that its intrusion probably gave rise to some of the metamorphism which caused the Huronian sediments to be described as Palmer gneiss. 3 During the course of a field study of the relations of this younger granite (the Republic granite) to the Huronian formations, the writer observed outcrops of dolomite, quartzite, and graywacke in the rocks still designated Palmer gneiss. The presence of these sediments, especially the dolomite, and their stratigraphic position below . . .