...a fraction of an inch upward, the average thickness, however, being quite small. Some of these beds are highly quartzose resembling a micaceous quartzite,...others are rich in biotite or hornblende producing dark to black bands indistinguishable in a hand specimen from mica and hornblende schists and gneisses derived...

...of these beds are highly quartzose, resembling a micaceous quartzite; others are rich in biotiteor hornblende, producing dark schists, which in a hand...indistinguishable from metamorphosed igneous masses. Within the area of Baltimore gneiss are numerous small bodies of metamorphosed granites and more basic igneous...

...vary from a fraction of an inch upward, the average breadth, however, being small. Some of these beds are highly quartzose, resembling a micaceous quartzite;...igneous masses. Within the areas of Baltimore gneiss are numerous small bodies of metamorphosed granites and more basic igneous rocks which have been intruded...

...breadth, however, being small. Some of these beds are highly quartzose, resembling a micaceous quartzitc: others are rich in biotite or hornblende, producing...igneous masses. Within the areas of Baltimore gneiss are numerous small bodies of metamorphosed granites and more basic igneous rocks which have been intruded...

...with accessory minerals, which are so distributed as to produce well-marked, gray-banded gneisses, the individual bands of which vary from a fraction...until they are practically indistinguishable from it. Extensive quarries have been opened in the Baltimore gneiss and worked for very many years on the north...

...Some of these bands are highly quartzose, resembling a micaceous quartzite; others are rich in biotitc or hornblende, producing dark schists, which in a...metamorphosed igneous masses. Within the areas of Baitimore gneiss are also numerous small bodies of metamorphosed granites and more basic igneous rocks,...

...Coastal Plain deposits in Harford County. This formation is limited on either side by igneous rocks. The second area of Baltimore gneiss is found in an...indistinguishable from metamorphosed igneous masses. Sometimes separated by an appreciable unconformity and at other times separated by ho apparent line,...

...an inch to several feet, the average thickness, however, being quite slight. Some of these bands arc highly quartzose, resembling a micaceous quartzite;...indistinguishable from metamorphosed igneous masses. Sometimes separated by an appreciable unconformity and at other times separated by no apparent line,...

...feet, the average thickness, however, being quite slight. Some of these bands are highly quartzosc, resembling a micaceous quartzite; others are rich...indistinguishable from metamorphosed igneous masses. Sometimes separated by an appreciable unconformity and at other times separated by no apparent line,...

...feet, the average thickness, however, being quite slight. Some of these bands are highly quartzosc, resembling a micaceous quartzite ; others are rich...hornblende, producing dark schists, which in a hand specimen arc indistinguishable from metamorphosed igneous masses. Sometimes separated by an appreciable unconformity...