Diller.] 356 | [January 21, 
cession rather than describe the felsites first and then the older and 
younger rocks. The order of formation has not been definitely 
determined in all cases, but ere long we hope to observe the facts 
that will indicate clearly the position of each rock in the chrono- 
logical series. 
STRATIFIED GROUP. 
In Melrose and Saugus the felsite is associated with a group of 
rocks consisting chiefly of quartzite and slates. This group has been 
called the stratified group and is rarely associated with ‘felsite. Its 
area in Melrose and Saugus is therefore of particular importance in 
determining the relations between the stratified group and the 
felsites. - : 
The quartzite and slates extend southwest from Melrose across 
Spot Pond. This southwestern extension of the stratified group 
across the region erroneously marked diorite by Mr. Crosby, 
separates the diorite from the felsite in that locality. The quartzite 
near the southwest corner of Spot Pond somewhat resembles felsite, 
and probably it is this fact that led Mr. Crosby to connect it with the 
felsite west of Pine Hill in Medford. The two rocks, quartzite and 
felsite, are entirely distinct and separated in that locality by a broad 
belt of granite. The area southwest of Crystal Lake in Melrose 
about the corner of Maine and Upham streets is occupied by the 
stratified group instead of felsite as marked by Mr. Crosby. In 
general the stratified group occupies the lowlands and the felsites 
form the hills. 
A fine exposure of the quartzite and slates occurs near the Melrose 
railroad station. The stratification is distinctly marked in a ledge 
north of Poplar street and along Vintage street. The strike of the 
formation at this place is N. 75° W. and dip 30° towards the north. 
The same rocks occur near the junction of Washington and Ravine 
streets on the Melrose-Stoneham line, and are here within several 
hundred feet of the nearest exposure of felsite south of Washington 
street. This is an important locality, from the fact that the quartzite 
and slate are here exposed nearer to the felsites than at any other 
place along the southern boundary of the stratified group. 
The rocks of the stratified group are said to vary greatly, but in 
the Melrose-Saugus area they are quite uniform throughout. The 
quartzite generally predominates. Its color is white or gray and it is 
clearly interstratified with the slates whose lines of sedimentation are 
distinct. 
