Let us take an imaginary trip through this region, starting on our wanderings from the Rhine, where it breaks through the vine-clad slate mountains of the Westerwald and the Eifel.  A short distance above the mouth of the Ahr we leave its banks, turning to the west, and entering the mountains at the village of Nieder Breisig.  A pretty valley leads us up through orchards and meadows.  The lower hills are covered with vineyards and the mountains with a dense growth of bushes, so that we do not obtain an extended view until we reach an elevated ridge.

[Illustration:  DISTANT VIEW OF THE VOLCANIC PORTION OF THE EIFEL, TAKEN FROM THE HEIGHTS OF THE SCHNEIFEL.]

The valley of the Rhine lies far below us, but the glittering surface of the river, with the little towns, the castles and villas and the gardens and vineyards on its banks are still visible, while in the background the mountains of the Westerwald have risen above the hills on the river.  This range stretches out into a long wooded ridge crowned by cone-shaped peaks of basalt.  To the northwest of this lies Siebengebirge, with its numerous domes and pinnacles, making a grand picture veiled in the blue mist of distance.  On the opposite side we have a very different view of curious dome and cone shaped summits surrounded by undulating plateaus or descending into deep ravines and gorges.  It is the western part of the volcanic region of Rhineland which lies before us, and in the center of which is the Laachersee or lake of Laach.  The origin of these volcanoes is not as remote as many suppose, but their activity must have continued for a comparatively long period, judging from the extent of their lava beds.

[Illustration:  THE SHORES OF LAACHERSEE.]

There was a time when the sea covered the lowlands of North Germany, and the waves of a deep bay washed the slopes of the Siebengebirge.  Then the bed of the Rhine lay in the highlands, which it gradually washed away until the surface of the river was far, far below the level of its old bed; and then the volcanoes poured forth their streams of lava over the surrounding plains.

In the course of time the surface of the country has changed so that these lava beds now lie on the mountain sides overhanging the valleys of to-day.  Some of the volcanoes sent forth melted stones and ashes from their summits, and streams of lava from their sides, while the craters of others cracked and then sank in, throwing their debris over the neighboring country.  In the Eifel there are many such funnels which now contain water forming beautiful lakes (Maaren), which add much to the scenery of the Eifel.  The Laachersee is the largest of these lakes.  In the mean time the channel of the Rhine had been worn away almost to its present level, but the mountains still sent forth their streams of lava, which stopped brooks and filled the ravines, and even the Rhine itself was dammed up by the great stream from Fornicherkopf forming what was formerly the Neuwied.  The old lava stream which obstructed the river is still to be seen in a towering wall of rock, extending close beside the road and track that follow the shore.