We have, however, distinct evidence of old land-surfaces, both in the Coal-measures and in other cases (as, for instance, in the well-known "dirt-bed" of the Purbeck series).

When, for example, we find the erect stumps of trees standing at right angles to the surrounding strata, we know that the surface through which these send their roots was at one time the surface of the dry land, or, in other words, was an ancient soil (fig.

19).
[Illustration: Fig.

19 .-- Erect Tree containing Reptilian remains.
Coal-measures, Nova Scotia.

(After Dawson.) In many cases fossils enable us to come to important conclusions as to the climate of the period in which they lived but only a few instances of this can be here adduced.