(9) 
generally contain minute nodules of carbonate of iron (siderite). 
which when, oxidized, give the surface of the rock a striking ap¬ 
pearance. Instead of siderite, iron pyrites in cubical crystals 
sometimes occurs. This series of beds is represented at the south 
end of Coaster’s Harbor Island, and forms the southern part of 
Easton’s Point. The veins which traverse these rocks often con¬ 
tain chlorite and sometimes also calcite and a little iron. The to¬ 
tal thickness is 600'—2000'. At Easton’s Point these argillytes 
are overlaid by the conglomerate with which we are all familiar, 
which is made up of pebbles of finely laminated quartzyte with 
some mica and contains Lingulce (Brachiopod Mollusks.) This 
rock recurs at Paradise on both sides of the hornblende and mica 
schist beds, and along the east shore of the island from Smith’s 
Beach to Black Point, and on the other side of the east passage at 
High Hill Point. There is some uncertainty as to whether the simi¬ 
lar conglomerate, which forms the summit of Miantonomah Hill, 
and that which covers the greater part of Coaster’s Harbor Island, 
and which differs considerably in its character from that of Easton’s 
Point, etc., belong to the same age. The thickness is about 750'. 
We have now examined the horizontal extent of the different 
beds and made what is called a geological map of the region. 
Idle next step is to ascertain the structure of these rock masses 
and their vertical relations to each other, so as to ascertain their 
relative age. Wc will not go through the wearisome details which 
this involves, but will satisfy ourselves with the results of much 
scientific drudgery. I will draw a line from the neighborhood of 
West Island, in a N. W. direction across our island, Conanicutand 
Dutch Islands, to the mainland on the west shore. This diagram 
represents a vertical section of the earth’s surface along that line— 
or more exactly it combines the main features of a belt extending 
some distance on either side of such a line. The inclinations of 
the strata were either directly ascertained by measurement or else 
indirectly inferred. We shall now be able to arrange the beds in 
chronological order. The oldest rocks are the protogines and 
gneiss, etc., etc., etc. In the table they are numbered and ar¬ 
ranged in that order beginning with the oldest. The rocks of the 
carboniferous period are Nos. 7-9. All those below No. 6 are 
of uncertain age. It is probable that some of them, as the horn- 
