“Are all the strata, then, sloped at this useful angle of which you speak?”
“Oh no, Bertha,” my uncle replied; “they are inclined at every conceivable angle, from perfect horizontality in some places, to a vertical face in others.”
Caroline observed that even the strata at which we were looking did not all appear to have the same dip, and wondered what could be the cause of the difference. My uncle said she was quite right in the fact; the strata at the eastern end of the valley had evidently a more sudden dip than the rest. “But,” he continued, “it is to facts, my little geologists, that we must at first confine ourselves: though causes and theories are highly interesting, at present they would only bewilder you. Those numerous strata, however, will afford some illustration of what I told you a few days ago about formations. You see by the frequent repetitions of the same substances in the cliff, that the same strata are frequently repeated, and in the same order. When this order is once known, the geologist is no longer perplexed by the number of strata; each throws light upon the other, and the whole combination receives the name of a series or formation. By comparing several of these series together, a resemblance in relation and position will be observed between many of them, which will lead to a still greater simplification of the different classes.”
My uncle then changed the conversation; we begged of him to go on with his geology; but we could not persuade him; he said if we attempted to remember too much, we should lose the whole. “Will you then give us a little lecture on it every day?”
“I will with great pleasure occasionally converse on the subject with both of you, my dear children,” said he; “and in our walks, or whenever a proper opportunity occurs, I will endeavour to give you a few general ideas of the structure of the globe. Hereafter we may perhaps enter more minutely into the details of the science, and then it will be time enough to talk of daily lectures.”
March 1st.—My dear mamma has often laughed at me for my love of little coincidences; and I have now a new one to tell her. I very lately mentioned in my journal some remarks, made by Dr. Walker of Edinburgh, on the seasons of the flowering of foreign plants; and this morning my uncle happened to see in the newspaper the following extract from an address to the Agricultural Society of St. Helena by General Walker, who is the son of that ingenious doctor. My uncle desired me to read it, and said that these speculations are very useful to inquiring minds; they furnish hints, and they naturally lead to new experiments, which elicit new facts.
“The functions of plants, as well as animals, depend on the air in which they live. I have observed that those of St. Helena which have been brought from another hemisphere, are very irregular in their annual progress; many of them, in the developement of their foliage, have adopted the law of nature peculiar to the country into which they have been transplanted—others, more obstinate, remain faithful to their former habits, and continue to follow the stated changes to which they had been accustomed. They all appear to maintain a struggle either before they adopt the habits which belong to the seasons of their new country, or decide on retaining their relations with the old. In yielding to external circumstances, they appear to have different tempers.
“This is often observed in plants of the same species appearing to hesitate before they adopt the mode of performing their functions. And when their decision is made, we are at a loss to discover an adequate cause. For instance, an oak raised from English seed, loses its leaves in a St. Helena winter of 68°; yet it experiences nothing like the difference of temperature, which, by analogy, might be supposed to cause that change.
“It would add to the natural history of vegetation, and improve our knowledge of the geography of plants, were the facts concerning their habits and changes, under different temperatures, carefully collected.”
2nd.—Miss Perceval, with whom I recollect you used to wish me to be acquainted, has come to spend a few weeks here; and I shall now not only have the pleasure of knowing a person you like, but of taking many a botanising walk with her as the Spring advances. She seems very gentle, and so unwilling to put herself forward, that my uncle is obliged to reproach her for withholding the stores of knowledge which she possesses; and he generally leads the conversation to such subjects as will make her display them a little, in spite of her diffidence.