Previous Nature Studies in the Acadian Land (1899) Next

 

A GOLD MINE.   65

 

must slant more and more till they are flat, and then begin to be piled up to make another book ledge. At the point where the rocks or strata are perpendicular it is termed an anteclinal ; at the point where they have flattened out it is termed a synclinal. Now from one of these anteclinals to another the distance is generally several miles. The ledges or strata are all of two varieties—quartzite and slate ; they rest against each other in alternating layers, perhaps of a few feet, or many feet, or a few inches in width. Both of these kinds of rocks are of shore origin ; they are sediments and sands ground up on a seashore many million years ago ; there can be no proper question as to this statement. Now supposing that all the region is bare, we would see white lines running along between the layers of rocks ; examination would show that they were veins of hard rock, varying in width from a mere line to five feet, and running easterly and westerly with the ledges in which they are enclosed. If you will put leaves of paper and pasteboard between the books I have imagined to be piled up, then these will show the positions of the veins in the rocks. Then you will see that some veins will be perpendicular and others more or less slanting; these are called ° regular " veins, or interstrati-


Previous Nature Studies in the Acadian Land (1899) Next