Alsace Part 2: The Geology - The Layout of the Land

Why is it important to understand the geology of a wine region? The answer is that it is the particular soil type that produces the unique flavors that end up in a wine from a certain region. When I first began my self-education on the geology of Alsace, I came upon this picture which allowed me to visualize what the important boundaries of Alsace was.¹

The above cartoon shows the major geological features of Alsace which is half mountain half valley comprising of the Vosges Mountains to the west, the location of the prime vineyard lands, the alluvial plains which are part of the Rhine graben, and the Rhine River to the east.
The soil types of the Vosges, the prime vineyard lands and the alluvial plains have all been extensively researched leading to the revelation that Alsace is home to a mosaic of soils of differing origins. The Website Vins Alsace² has a beautiful sampling of terroir types and where they are located:

To understand how this mosaic of soil types came into being, is to travel back in time some 300 million years ago and this is the question that I am seeking to answer in the upcoming blogs on Alsatian geology.
References:
1. Tasting Notes from Astor Wine and Spirits, Wine & Sake.
2. Vins Alsace, Geological Past.